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7.7: Cancer Genetics (Exercises) - Biology

7.7: Cancer Genetics (Exercises) - Biology



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These are homework exercises to accompany Nickle and Barrette-Ng's "Online Open Genetics" TextMap. It includes the study of genes, themselves, how they function, interact, and produce the visible and measurable characteristics we see in individuals and populations of species as they change from one generation to the next, over time, and in different environments.

Study Questions:

13.1 Why do oncogenes tend to be dominant, but mutations in tumor suppressors tend to be recessive?

13.2 What tumor suppressing functions are controlled by p53? How can a single gene affect so many different biological pathways?

13.3 Are all carcinogens mutagens? Are all mutagens carcinogens? Explain why or why not.

13.4 Imagine that a laboratory reports that feeding a chocolate to laboratory rats increases the incidence of cancer. What other details would you want to know before you stopped eating chocolate?

13.5 Do all women with HPV get cancer? Why or why not? Do all women with mutations in BRCA1 get cancer? Why or why not?


Is Cancer a Genetic Disease?

The cancer industry is fully committed to the idea that a cancer cell is a genetic frankenstein cell whose only goal is to destroy and kill the patient. This is the only way the use of knives (surgery), toxic injections (chemotherapy) and ionizing radiation (radiotherapy) can be justified as treatments. If it is ever proven or acknowledged that these treatments are doing more harm than good, the industry falls.

Cancer The Mystery Solved Series Quick-links:

The official position of the cancer establishment is that “cancer is a genetic disease,”(1) whereby a specific set of genetic mutations cause a single cell to turn irreversibly cancerous and multiply out-of-control, until enough of its mutant clones collectively form a tumor that strives to kill the host.

If this theory is correct, it means that cancer cells are like parasites that must be eradicated at all costs even if patients are injured or nearly killed in the process. It also means that nothing in our environment or the way we live our lives have any bearing whatsoever on whether or not we develop cancer – if we get it, it’s simply bad luck.

And in this paradigm, since there’s nothing we can do to prevent cancer from arising or stop it from progressing, if we happen to be one of the ‘unlucky’ ones who are diagnosed with the disease, we must depend on people more sophisticated than us for answers.

However, if cancer truly were a genetic disease then you’d think the 500 billion dollars spent on genetic cancer research over the past 50 years would have rendered us at least some progress. It makes you wonder – maybe researchers have been looking in the wrong place for answers?


In Treatment for Leukemia, Glimpses of the Future

ST. LOUIS — Genetics researchers at Washington University, one of the world’s leading centers for work on the human genome, were devastated. Dr. Lukas Wartman, a young, talented and beloved colleague, had the very cancer he had devoted his career to studying. He was deteriorating fast. No known treatment could save him. And no one, to their knowledge, had ever investigated the complete genetic makeup of a cancer like his.

So one day last July, Dr. Timothy Ley, associate director of the university’s genome institute, summoned his team. Why not throw everything we have at seeing if we can find a rogue gene spurring Dr. Wartman’s cancer, adult acute lymphoblastic leukemia, he asked? “It’s now or never,” he recalled telling them. “We will only get one shot.”

Dr. Ley’s team tried a type of analysis that they had never done before. They fully sequenced the genes of both his cancer cells and healthy cells for comparison, and at the same time analyzed his RNA, a close chemical cousin to DNA, for clues to what his genes were doing.

The researchers on the project put other work aside for weeks, running one of the university’s 26 sequencing machines and supercomputer around the clock. And they found a culprit — a normal gene that was in overdrive, churning out huge amounts of a protein that appeared to be spurring the cancer’s growth.

Even better, there was a promising new drug that might shut down the malfunctioning gene — a drug that had been tested and approved only for advanced kidney cancer. Dr. Wartman became the first person ever to take it for leukemia.

And now, against all odds, his cancer is in remission and has been since last fall.

While no one can say that Dr. Wartman is cured, after facing certain death last fall, he is alive and doing well. Dr. Wartman is a pioneer in a new approach to stopping cancer. What is important, medical researchers say, is the genes that drive a cancer, not the tissue or organ — liver or brain, bone marrow, blood or colon — where the cancer originates.

One woman’s breast cancer may have different genetic drivers from another woman’s and, in fact, may have more in common with prostate cancer in a man or another patient’s lung cancer.

Under this new approach, researchers expect that treatment will be tailored to an individual tumor’s mutations, with drugs, eventually, that hit several key aberrant genes at once. The cocktails of medicines would be analogous to H.I.V. treatment, which uses several different drugs at once to strike the virus in a number of critical areas.

Researchers differ about how soon the method, known as whole genome sequencing, will be generally available and paid for by insurance — estimates range from a few years to a decade or so. But they believe that it has enormous promise, though it has not yet cured anyone.

With a steep drop in the costs of sequencing and an explosion of research on genes, medical experts expect that genetic analyses of cancers will become routine. Just as pathologists do blood cultures to decide which antibiotics will stop a patient’s bacterial infection, so will genome sequencing determine which drugs might stop a cancer.

“Until you know what is driving a patient’s cancer, you really don’t have any chance of getting it right,” Dr. Ley said. “For the past 40 years, we have been sending generals into battle without a map of the battlefield. What we are doing now is building the map.”

Large drug companies and small biotechs are jumping in, starting to test drugs that attack a gene rather than a tumor type.

Image

Leading cancer researchers are starting companies to find genes that might be causing an individual’s cancer to grow, to analyze genetic data and to find and test new drugs directed against these genetic targets. Leading venture capital firms are involved.

For now, whole genome sequencing is in its infancy and dauntingly complex. The gene sequences are only the start — they come in billions of small pieces, like a huge jigsaw puzzle. The arduous job is to figure out which mutations are important, a task that requires skill, experience and instincts.

So far, most who have chosen this path are wealthy and well connected. When Steve Jobs had exhausted other options to combat pancreatic cancer, he consulted doctors who coordinated his genetic sequencing and analysis. It cost him $100,000, according to his biographer. The writer Christopher Hitchens went to the head of the National Institutes of Health, Dr. Francis Collins, who advised him on where to get a genetic analysis of his esophageal cancer.

Harvard Medical School expects eventually to offer whole genome sequencing to help cancer patients identify treatments, said Heidi L. Rehm, who heads the molecular medicine laboratory at Harvard’s Partners Healthcare Center for Personalized Genetic Medicine. But later this year, Partners will take a more modest step, offering whole genome sequencing to patients with a suspected hereditary disorder in hopes of identifying mutations that might be causing the disease.

Whole genome sequencing of the type that Dr. Wartman had, Dr. Rehm added, “is a whole other level of complexity.”

Dr. Wartman was included by his colleagues in a research study, and his genetic analysis was paid for by the university and research grants. Such opportunities are not available to most patients, but Dr. Ley noted that the group had done such an analysis for another patient the year before and that no patients were being neglected because of the urgent work to figure out Dr. Wartman’s cancer.

“The precedent for moving quickly on a sample to make a key decision was already established,” Dr. Ley said.

Ethicists ask whether those with money and connections should have options far out of reach for most patients before such treatments become a normal part of medicine. And will people of more limited means be tempted to bankrupt their families in pursuit of a cure at the far edges?

“If we say we need research because this is a new idea, then why is it that rich people can even access it?” asked Wylie Burke, professor and chairwoman of the department of bioethics at the University of Washington. The saving grace, she said, is that the method will become available to all if it works.

A Life in Medicine

It was pure happenstance that landed Dr. Wartman in a university at the forefront of cancer research. He grew up in small-town Indiana, aspiring to be a veterinarian like his grandfather. But in college, he worked summers in hospitals and became fascinated by cancer. He enrolled in medical school at Washington University in St. Louis, where he was drawn to research on genetic changes that occur in cancers of the blood. Dr. Wartman knew then what he wanted to do — become a physician researcher.

Those plans fell apart in the winter of 2002, his last year of medical school, when he went to California to be interviewed for a residency program at Stanford. On the morning of his visit, he was nearly paralyzed by an overwhelming fatigue.

“I could not get out of bed for an interview that was the most important of my life,” Dr. Wartman recalled. Somehow, he forced himself to drive to Palo Alto in a drenching rain. He rallied enough to get through the day.


Physical Activity and Cancer

Physical activity is defined as any movement that uses skeletal muscles and requires more energy than resting. Physical activity can include walking, running, dancing, biking, swimming, performing household chores, exercising, and engaging in sports activities.

A measure called the metabolic equivalent of task, or MET, is used to characterize the intensity of physical activity. One MET is the rate of energy expended by a person sitting at rest. Light-intensity activities expend less than 3 METs, moderate-intensity activities expend 3 to 6 METs, and vigorous activities expend 6 or more METs (1).

Sedentary behavior is any waking behavior characterized by an energy expenditure of 1.5 or fewer METs while sitting, reclining, or lying down (1). Examples of sedentary behaviors include most office work, driving a vehicle, and sitting while watching television.

A person can be physically active and yet spend a substantial amount of time being sedentary.

What is known about the relationship between physical activity and cancer risk?

Evidence linking higher physical activity to lower cancer risk comes mainly from observational studies, in which individuals report on their physical activity and are followed for years for diagnoses of cancer. Although observational studies cannot prove a causal relationship, when studies in different populations have similar results and when a possible mechanism for a causal relationship exists, this provides evidence of a causal connection.

There is strong evidence that higher levels of physical activity are linked to lower risk of several types of cancer (2–4).

  • Bladder cancer: In a 2014 meta-analysis of 11 cohort studies and 4 case-control studies, the risk of bladder cancer was 15% lower for individuals with the highest level of recreational or occupational physical activity than in those with the lowest level (5). A pooled analysis of over 1 million individuals found that leisure-time physical activity was linked to a 13% reduced risk of bladder cancer (6).
  • Breast cancer: Many studies have shown that physically active women have a lower risk of breast cancer than inactive women. In a 2016 meta-analysis that included 38 cohort studies, the most physically active women had a 12–21% lower risk of breast cancer than those who were least physically active (7). Physical activity has been associated with similar reductions in risk of breast cancer among both premenopausal and postmenopausal women (7, 8). Women who increase their physical activity after menopause may also have a lower risk of breast cancer than women who do not (9, 10).
  • Colon cancer: In a 2016 meta-analysis of 126 studies, individuals who engaged in the highest level of physical activity had a 19% lower risk of colon cancer than those who were the least physically active (11).
  • Endometrial cancer: Several meta-analyses and cohort studies have examined the relationship between physical activity and the risk of endometrial cancer (cancer of the lining of the uterus) (12–15). In a meta-analysis of 33 studies, highly physically active women had a 20% lower risk of endometrial cancer than women with low levels of physical activity (12). There is some evidence that the association is indirect, in that physical activity would have to reduce obesity for the benefits to be observed. Obesity is a strong risk factor for endometrial cancer (12–14).
  • Esophageal cancer: A 2014 meta-analysis of nine cohort and 15 case–control studies found that the individuals who were most physically active had a 21% lower risk of esophageal adenocarcinoma than those who were least physically active (16).
  • Kidney (renal cell) cancer: In a 2013 meta-analysis of 11 cohort studies and 8 case–control studies, individuals who were the most physically active had a 12% lower risk of renal cancer than those who were the least active (17). A pooled analysis of over 1 million individuals found that leisure-time physical activity was linked to a 23% reduced risk of kidney cancer (6).
  • Stomach (gastric) cancer: A 2016 meta-analysis of 10 cohort studies and 12 case–control studies reported that individuals who were the most physically active had a 19% lower risk of stomach cancer than those who were least active (18).

There is some evidence that physical activity is associated with a reduced risk of lung cancer (2, 4). However, it is possible that differences in smoking, rather than in physical activity, are what explain the association of physical activity with reduced risk of lung cancer. In a 2016 meta-analysis of 25 observational studies, physical activity was associated with reduced risk of lung cancer among former and current smokers but was not associated with risk of lung cancer among never smokers (19).

For several other cancers, there is more limited evidence of an association. These include certain cancers of the blood, as well as cancers of the pancreas, prostate, ovaries, thyroid, liver, and rectum (2, 6).

How might physical activity be linked to reduced risks of cancer?

Exercise has many biological effects on the body, some of which have been proposed to explain associations with specific cancers. These include:

  • Lowering the levels of sex hormones, such as estrogen, and growth factors that have been associated with cancer development and progression (20) [breast, colon]
  • Preventing high blood levels of insulin, which has been linked to cancer development and progression (20) [breast, colon]
  • Reducing inflammation
  • Improving immune system function
  • Altering the metabolism of bile acids, decreasing exposure of the gastrointestinal tract to these suspected carcinogens (21, 22) [colon]
  • Reducing the time it takes for food to travel through the digestive system, which decreases gastrointestinal tract exposure to possible carcinogens [colon]
  • Helping to prevent obesity, which is a risk factor for many cancers

What is known about the relationship between being sedentary and the risk of cancer?

Although there are fewer studies of sedentary behavior and cancer risk than of physical activity and cancer risk, sedentary behavior—sitting, reclining, or lying down for extended periods of time (other than sleeping)—is a risk factor for developing many chronic conditions and premature death (4, 23, 24). It may also be associated with increased risk for certain cancers (23, 25).

How much physical activity is recommended?

The U.S. Department of Health and Human Services Physical Activity Guidelines for Americans, 2nd edition, released in 2018 (1), recommends that, for substantial health benefits and to reduce the risk of chronic diseases, including cancer, adults engage in

  • 150 to 300 minutes of moderate-intensity aerobic activity, 75 to 100 minutes of vigorous aerobic activity, or an equivalent combination of each intensity each week. This physical activity can be done in episodes of any length.
  • muscle-strengthening activities at least 2 days a week
  • balance training, in addition to aerobic and muscle-strengthening activity

Is physical activity beneficial for cancer survivors?

Yes. A report of the 2018 American College of Sports Medicine International Multidisciplinary Roundtable on Physical Activity and Cancer Prevention and Control (26) concluded that exercise training and testing are generally safe for cancer survivors and that every survivor should maintain some level of physical activity.

The Roundtable also found

  • strong evidence that moderate-intensity aerobic training and/or resistance exercise during and after cancer treatment can reduce anxiety, depressive symptoms, and fatigue and improve health-related quality of life and physical function
  • strong evidence that exercise training is safe in persons who have or might develop breast-cancer - related lymphedema
  • some evidence that exercise is beneficial for bone health and sleep quality
  • insufficient evidence that physical activity can help prevent cardiotoxicity or chemotherapy-induced peripheral neuropathy or improve cognitive function, falls, nausea, pain, sexual function, or treatment tolerance

In addition, research findings have raised the possibility that physical activity may have beneficial effects on survival for patients with breast, colorectal, and prostate cancers (26, 27).

  • Breast cancer: In a 2019 systematic review and meta-analysis of observational studies, breast cancer survivors who were the most physically active had a 42% lower risk of death from any cause and a 40% lower risk of death from breast cancer than those who were the least physically active (28).
  • Colorectal cancer: Evidence from multiple epidemiologic studies suggests that physical activity after a colorectal cancer diagnosis is associated with a 30% lower risk of death from colorectal cancer and a 38% lower risk of death from any cause (4).
  • Prostate cancer: Limited evidence from a few epidemiologic studies suggests that physical activity after a prostate cancer diagnosis is associated with a 33% lower risk of death from prostate cancer and a 45% lower risk of death from any cause (4).

There is very limited evidence for beneficial effects of physical activity on survival for other cancers, including non-Hodgkin lymphoma, stomach cancer, and malignant glioma (4).

What additional research is under way on the relationship between physical activity and cancer?

Findings from observational studies provide much evidence for a link between higher levels of physical activity and lower risk of cancer. However, these studies cannot fully rule out the possibility that active people have lower cancer risk because they engage in other healthy lifestyle behaviors. For this reason, clinical trials that randomly assign participants to exercise interventions provide the strongest evidence because they eliminate bias caused by pre-existing illness and attendant physical inactivity.

To confirm the observational evidence and define the potential magnitude of the effect, several large clinical trials are examining physical activity and/or exercise interventions in cancer patients and survivors. These include the Breast Cancer Weight Loss (BWEL) trial in newly diagnosed breast cancer patients, the CHALLENGE trial in colon cancer patients who have recently completed chemotherapy (29), and the INTERVAL-GAP4 trial in men with metastatic, castrate-resistant prostate cancer (30).

Many additional questions have yet to be answered in several broad areas of research on physical activity and cancer:

  • What are the mechanisms by which physical activity reduces cancer risk?
  • What is the optimal time in life, intensity, duration, and/or frequency of physical activity needed to reduce the risk of cancer, both overall and for specific sites?
  • Is sedentary behavior associated with increased risk of cancer?
  • Does the association between physical activity and cancer differ by age or race/ethnicity?
  • Does physical activity reduce the risk of cancer in people who have inherited a geneticvariant that increases cancer risk?
Selected References

2018 Physical Activity Guidelines Advisory Committee. 2018 Physical Activity Guidelines Advisory Committee Scientific Report. Washington, DC: U.S. Department of Health and Human Services, 2018.

McTiernan A, Friedenreich CM, Katzmarzyk PT, et al. Physical activity in cancer prevention and survival: A systematic review. Medicine and Science in Sports and Exercise 2019 51(6):1252-1261.

Rezende LFM, Sá TH, Markozannes G, et al. Physical activity and cancer: an umbrella review of the literature including 22 major anatomical sites and 770 000 cancer cases. British Journal of Sports Medicine 2018 52(13):826-833.

Patel AV, Friedenreich CM, Moore SC, et al. American College of Sports Medicine Roundtable Report on physical activity, sedentary behavior, and cancer prevention and control. Medicine and Science in Sports and Exercise 2019 51(11):2391-2402.

Keimling M, Behrens G, Schmid D, Jochem C, Leitzmann MF. The association between physical activity and bladder cancer: systematic review and meta-analysis. British Journal of Cancer 2014 110(7):1862-1870.

Moore SC, Lee IM, Weiderpass E, et al. Association of leisure-time physical activity with risk of 26 types of cancer in 1.44 million adults. JAMA Internal Medicine 2016 176(6):816-825.

Pizot C, Boniol M, Mullie P, et al. Physical activity, hormone replacement therapy and breast cancer risk: A meta-analysis of prospective studies. European Journal of Cancer 2016 52:138-154.

Hardefeldt PJ, Penninkilampi R, Edirimanne S, Eslick GD. Physical activity and weight loss reduce the risk of breast cancer: A meta-analysis of 139 prospective and retrospective studies. Clinical Breast Cancer 2018 18(4):e601-e612.

Eliassen AH, Hankinson SE, Rosner B, Holmes MD, Willett WC. Physical activity and risk of breast cancer among postmenopausal women. Archives of Internal Medicine 2010 170(19):1758-1764.

Fournier A, Dos Santos G, Guillas G, et al. Recent recreational physical activity and breast cancer risk in postmenopausal women in the E3N cohort. Cancer Epidemiology, Biomarkers & Prevention 2014 23(9):1893-1902.

Liu L, Shi Y, Li T, et al. Leisure time physical activity and cancer risk: evaluation of the WHO's recommendation based on 126 high-quality epidemiological studies. British Journal of Sports Medicine 2016 50(6):372-378.

Schmid D, Behrens G, Keimling M, et al. A systematic review and meta-analysis of physical activity and endometrial cancer risk. European Journal of Epidemiology 2015 30(5):397-412.

Du M, Kraft P, Eliassen AH, et al. Physical activity and risk of endometrial adenocarcinoma in the Nurses' Health Study. International Journal of Cancer 2014 134(11):2707-2716.

Friedenreich C, Cust A, Lahmann PH, et al. Physical activity and risk of endometrial cancer: The European prospective investigation into cancer and nutrition. International Journal of Cancer 2007 121(2):347-355.

Borch KB, Weiderpass E, Braaten T, et al. Physical activity and risk of endometrial cancer in the Norwegian Women and Cancer (NOWAC) study. International Journal of Cancer 2017 140(8):1809-1818.

Behrens G, Jochem C, Keimling M, et al. The association between physical activity and gastroesophageal cancer: systematic review and meta-analysis. European Journal of Epidemiology 2014 29(3):151-170.

Behrens G, Leitzmann MF. The association between physical activity and renal cancer: systematic review and meta-analysis. British Journal of Cancer 2013 108(4):798-811.

Psaltopoulou T, Ntanasis-Stathopoulos I, Tzanninis IG, et al. Physical activity and gastric cancer risk: A systematic review and meta-analysis. Clinical Journal of Sports Medicine 2016 26(6):445-464.

Schmid D, Ricci C, Behrens G, Leitzmann MF. Does smoking influence the physical activity and lung cancer relation? A systematic review and meta-analysis. European Journal of Epidemiology 2016 31(12):1173-1190.

Winzer BM, Whiteman DC, Reeves MM, Paratz JD. Physical activity and cancer prevention: a systematic review of clinical trials. Cancer Causes and Control 2011 22(6):811-826.

Wertheim BC, Martinez ME, Ashbeck EL, et al. Physical activity as a determinant of fecal bile acid levels. Cancer Epidemiology, Biomarkers & Prevention 2009 18(5):1591-1598.

Bernstein H, Bernstein C, Payne CM, Dvorakova K, Garewal H. Bile acids as carcinogens in human gastrointestinal cancers. Mutation Research 2005 589(1):47-65.

Schmid D, Leitzmann MF. Association between physical activity and mortality among breast cancer and colorectal cancer survivors: a systematic review and meta-analysis. Annals of Oncology 2014 25(7):1293-1311.

Biswas A, Oh PI, Faulkner GE, et al. Sedentary time and its association with risk for disease incidence, mortality, and hospitalization in adults: a systematic review and meta-analysis. Annals of Internal Medicine 2015 162(2):123-132.

Patel AV, Hildebrand JS, Campbell PT, et al. Leisure-time spent sitting and site-specific cancer incidence in a large U.S. cohort. Cancer Epidemiology, Biomarkers & Prevention 2015 24(9):1350-1359.

Campbell KL, Winters-Stone KM, Wiskemann J, et al. Exercise guidelines for cancer survivors: Consensus statement from International Multidisciplinary Roundtable. Medicine and Science in Sports and Exercise 2019 51(11):2375-2390.

Schmitz KH, Campbell AM, Stuiver MM, et al. Exercise is medicine in oncology: Engaging clinicians to help patients move through cancer. CA: A Cancer Journal for Clinicians 2019 69(6):468-484.

Spei ME, Samoli E, Bravi F, et al. Physical activity in breast cancer survivors: A systematic review and meta-analysis on overall and breast cancer survival. Breast 2019 44:144-152.

Courneya KS, Booth CM, Gill S, et al. Curr Oncol. The Colon Health and Life-Long Exercise Change trial: a randomized trial of the National Cancer Institute of Canada Clinical Trials Group. Current Oncology 2008 15(6):279-285.

Newton RU, Kenfield SA, Hart NH, et al. Intense exercise for survival among men with metastatic castrate-resistant prostate cancer (INTERVAL-GAP4): a multicentre, randomised, controlled phase III study protocol. BMJ Open 2018 8(5):e022899.


Study: Getting Enough Exercise Lowers Risk of 7 Cancers

Getting recommended amounts of physical activity is linked to a lower risk for 7 cancer types, according to a study from the American Cancer Society, the National Cancer Institute, and the Harvard T.H. Chan School of Public Health.

Health experts have known for a long time that exercise is linked with a lower risk of several cancers, but they’ve had limited evidence about how much exercise is needed. The new study found that the equivalent of 2.5 to 5 hours of moderate-intensity activity per week (or 1.25 to 2.5 hours of vigorous activity) provided a significant benefit. The study was published December 26, 2019 in the Journal of Clinical Oncology.

“This paper provides some of the most robust evidence to date that in fact meeting current physical activity recommendations is sufficient for 7 different types of cancer prevention,” said Alpa Patel, PhD, co-author of the study and senior scientific director of epidemiology research at the American Cancer Society.

The researchers looked at 9 prospective studies involving more than 750,000 adults with an average age of 62, who answered questions about how much leisure-time physical activity they got. This is time spent outside of work on activities for the purpose of getting exercise, such as playing a sport, working out, or taking a walk. Moderate-intensity activities are at about the level of a brisk walk. They burn 3 to 6 times as much energy measured in terms of metabolic equivalent tasks (METs) as sitting quietly. Vigorous-intensity activities burn more than 6 METs.

The study found that getting recommended amounts of activity (7.5 – 15 MET hours per week, which equates to 2.5 – 5 hours of moderate-intensity activity or 1.25 – 2.5 hours of vigorous activity) significantly lowered the risk for 7 of the 15 cancer types studied: colon, breast, endometrial, kidney, multiple myeloma, liver, and non-Hodgkin lymphoma. Getting more MET hours was associated with an even greater reduction in risk for some of the cancer types.

Specifically, physical activity was linked with:

  • An 8% lower risk of colon cancer in men for 7.5 MET hours per week and a 14% lower risk for 15 MET hours per week
  • A 6% lower risk of breast cancer in women for 7.5 MET hours per week and a 10% lower risk for 15 MET hours per week
  • A 10% lower risk of endometrial cancer in women for 7.5 MET hours per week and an 18% lower risk for 15 MET hours per week
  • An 11% lower risk of kidney cancer for 7.5 MET hours per week and a 17% lower risk for 15 MET hours per week
  • A 14% lower risk of multiple myeloma for 7.5 MET hours per week and a 19% lower risk for 15 MET hours per week
  • An 18% lower risk of liver cancer for 7.5 MET hours per week and a 27% lower risk for 15 MET hours per week
  • An 11% lower risk of non-Hodgkin lymphoma in women for 7.5 MET hours per week and an 18% lower risk for 15 MET hours per week

Genetics and Cancer

Some types of cancer run in certain families, but most cancers are not clearly linked to the genes we inherit from our parents. Gene changes that start in a single cell over the course of a person's life cause most cancers. In this section you can learn more about the complex links between genes and cancer.

Genes and Cancer

Advances in genetics and molecular biology have improved our knowledge of the inner workings of cells, the basic building blocks of the body. Here we review how cells can change during a person’s life to become cancer, how certain types of changes can build on inherited gene changes to speed up the development of cancer, and how this information can help us better prevent and treat cancer.

Family Cancer Syndromes

Cancer is such a common disease that it is no surprise that many families have at least a few members who have had cancer. Sometimes, certain types of cancer seem to run in some families. But only a small portion of all cancers are inherited. This document focuses on those cancers.

Genetic Testing for Cancer

Genetic testing can be useful for people with certain types of cancer that seem to run in their families, but these tests aren't recommended for everyone. Here we offer basic information to help you understand what genetic testing is and how it is used in cancer.


Genetic Counseling and Genetic Testing for Hereditary Cancer at MSK

Physician-scientist Kenneth Offit founded MSK’s Clinical Genetics Service in 1992.

Genetic counseling and cancer risk assessment is an important part of cancer care at Memorial Sloan Kettering. Through this process, our genetic counselors and doctors will guide you through the process of learning about your risk for inherited cancer. Genetic counselors are experts in collecting and assessing information about family history.

Based on genetic test results and family cancer history, the Clinical Genetics Service (CGS) provides patients and family members with recommendations for surveillance and risk reduction. These recommendations are provided in a compassionate and easy-to-understand manner.

CGS’s aim is to provide people who have cancer and their family members with compassionate care. We help people understand how a diagnosis of cancer in one family member may impact the health of others. Knowing that a genetic predisposition to cancer exists in a family can help identify other relatives who are at risk for the disease. This knowledge can lead to cancer prevention and early intervention for entire families.

If you have been diagnosed with cancer or have a family history of cancer, you may be interested in learning more about genetic counseling and the options for genetic testing. Genetic counseling is often recommended for people who develop cancer at a young age (for example, breast cancer before age 45). It may also be recommended for people with multiple close family members who have had the same type of cancer. We take many risk factors into consideration when evaluating someone for a potential hereditary risk of cancer.

If you are interested in learning about a potential hereditary risk of cancer, we encourage you to read through this guide and contact our Clinical Genetics Service.


Biology: Middle School: Grades 6, 7 and 8 Quizzes

The truth is there are some really gory things that you have to do and learn about in biology. Believe us, you really don’t want to be dissecting a frog or studying the urinary tract of a horse immediately before a meal! You might find that you are on the side of Kary Mullis who said ‘I like writing about biology, not doing it’.

But, setting that aside for a minute, there are a quadrillion ‘nice’ and fascinating things to learn about. That is because biology is the study of living organisms in all their myriad, wondrous forms.

Along the way, you’ll get many fascinating insights into the animal and plant kingdoms. For instance, did you know that the Kakapo bird is on the verge of extinction because it is unable to fly and it has a strong, pleasant odour that enables predators to easily find it? That is one incredibly unfortunate bird!

And here’s something else you maybe didn’t know: honey never spoils – you could eat honey produced today in a thousand year’s time. And yet another one: it takes only one malaria-carrying mosquito to threaten the life of a human being but it would take over a million mosquitoes to suck all the blood from that same person.

We seem to have strayed from ‘nice’ so let’s get back into the ultra-safe world of quizzes. There is genetics to learn about and biofuels along with cloning and blood (whoops, there we go again). Then there’s enzymes and osmosis. All will be revealed in the quizzes that follow.


Graduate Study

The Department of Biology offers graduate work leading to the Doctor of Philosophy. Students may choose from among the following fields of specialization.

Biochemistry, Biophysics, and Structural Biology focus on improving our understanding of molecular processes central to life. Using in vitro approaches, biochemists and biophysicists analyze the mechanisms of biological information transfer, from maintenance and replication of the genome to protein synthesis, sorting, and processing. Structural biologists elucidate the molecular shapes of biological macromolecules and complexes and determine how structure enables function. Applying principles and tools from chemistry and physics, biochemists and biophysicists elaborate the details of protein and nucleic acid folding and interactions, biomolecular dynamics, catalysis, and macromolecular assembly.

Cancer Biology involves the discovery of genes implicated in cancer, the identification of cell biological processes affected during tumorigenesis, and the development of potential new therapeutic targets. Cancer biologists employ genetic approaches, including classical genetics, to determine the components of growth control pathways in model organisms, cloning of human oncogenes and tumor suppressor genes, and generating mutant mouse strains to study these and other cancer-associated genes. They also perform biochemical and cell biological studies to elucidate the function of cancer genes, the details of proliferation, cell cycle and cell death pathways, the nature of cell-cell and cell-matrix interactions, and the mechanisms of chromosome stability and of DNA repair, replication, and transcription.

Cell Biology is the study of processes carried out by individual cells, such as cell division, organelle inheritance and biogenesis, signal transduction, and motility. These processes are often affected by components in the environment, including nutrients, growth signals, and cell-cell contact. Cell biologists study these processes using single-celled organisms, such as bacteria and yeast multicellular organisms, such as zebrafish and mice established mammalian tissue culture lines and primary cell cultures derived from recombinant animals.

Computational Biology applies quantitative methods to the study of molecular, cellular, and organismal biology. Computational biologists develop and apply models, analyze data, and run simulations to study nucleic acid and protein sequences, biomolecular structures and functions, cellular information processing, tissue morphogenesis, and emergent behaviors.

Genetics is the study of genes, genetic variation, and heredity in living organisms that range in complexity from viruses to single-celled organisms to multicellular organisms, including humans. Geneticists seek to understand the transmission of genes by analyzing DNA replication, DNA repair, chromosome segregation, and cell division. They also use genetic and genomic tools to identify and analyze the genes and gene regulators required for normal biological processes, including development, sex determination, and aging, as well as for the etiology of disease.

Human Disease applies molecular genetics to the problems of human disease. The range of disease areas includes developmental defects, cancer, atherosclerosis and heart disease, neuromuscular diseases, and diseases of other organ systems. Researchers use genetic and genomic strategies to identify, isolate, and characterize genes that cause and contribute to the etiology of human diseases. They explore the mechanisms underlying developmental defects and diseases through the comparison of the genetic pathways in humans and model organisms. They also isolate cells from affected patients to generate novel assay systems to examine gene-function-pathology relationships.

Immunology focuses on the genetic, cellular, and molecular mechanisms by which organisms respond to and eliminate infections by a large number of pathogens. The immune response requires an elaborate collaboration of different cells of the immune system, including macrophages, B lymphocytes, and T lymphocytes. Immunologists study the role of the immune system not just in response to infection but also in a range of human diseases, including cancer.

Microbiology is the study of microscopic organisms, such as bacteria, viruses, archaea, fungi, and protozoa. Exploiting sophisticated genetic, molecular biological, and biochemical systems available for microorganisms, microbiologists obtain high-resolution insights into the fundamental processes necessary for life and explore ways to manipulate microorganisms to achieve particular desired ends. They also determine how aspects of the microbial life cycle and lifestyle enable their survival within particular biological niches and facilitate interactions with their environment.

Neurobiology seeks to understand how the remarkable diversity in neuronal cell types and their connections are established and how changes in them underlie learning and thinking. Neurobiologists identify and characterize the molecules involved in specifying neuronal cell fate in vertebrates and invertebrates, and in guiding axons to their correct targets.

Stem Cell and Developmental Biology explores how a germ line stem cell develops into a multicellular organism, which requires that cells divide, differentiate, and assume their proper positions relative to one another as they produce organ systems and entire organisms. Stem cells are unusual cells in the body that retain the capacity to both self-renew and differentiate. Stem cell researchers identify the molecular mechanisms underlying stem cell renewal and differentiation, and use stem cells for disease modeling and regenerative medicine.

Admission Requirements for Graduate Study

In the Department of Biology, the Master of Science is not a prerequisite for a program of study leading to the doctorate.

The department modifies the General Institute Requirements for admission to graduate study as follows: 18.01 Calculus , 18.02 Calculus one year of college physics 5.12 Organic Chemistry I professional subjects including general biochemistry, genetics, and physical chemistry. However, students may make up some deficiencies over the course of their graduate work.

Doctor of Philosophy

The General Degree Requirements for the Doctor of Philosophy are listed under Graduate Education. In the departmental program, each graduate student is expected to acquire solid foundations sufficient for approaching biological questions using the methods of biochemistry, genetics, and quantitative analysis. Most students take subjects in these areas during the first year. All students are required to take three subjects:

7.50Method and Logic in Molecular Biology12
7.51Principles of Biochemical Analysis12
7.52Genetics for Graduate Students12

7.50 is a seminar designed specifically to introduce graduate students to in-depth discussion and analysis of topics in molecular biology.

Students have a choice of several elective subjects, which have been designed for the entering graduate student. One of the elective subjects must focus on computational and quantitative approaches to biology. Typically, students choose one of the following subjects:

7.571
& 7.572
Quantitative Analysis of Biological Data
and Quantitative Measurements and Modeling of Biological Systems
12
7.81[J]Systems Biology12

In addition to providing a strong formal background in biology, the first-year program serves to familiarize the students with faculty and students in all parts of the department.

Interdisciplinary Programs

Joint Program with the Woods Hole Oceanographic Institution

The Joint Program with the Woods Hole Oceanographic Institution (WHOI) is intended for students whose primary career objective is oceanography or oceanographic engineering. Students divide their academic and research efforts between the campuses of MIT and WHOI. Joint Program students are assigned an MIT faculty member as academic advisor thesis research may be supervised by MIT or WHOI faculty. While in residence at MIT, students follow a program similar to that of other students in their home department. The program is described in more detail under Interdisciplinary Graduate Programs.

Master of Engineering in Computer Science and Molecular Biology (Course 6-7P)

The Departments of Biology and Electrical Engineering and Computer Science jointly offer a Master of Engineering in Computer Science and Molecular Biology (6-7P). A detailed description of the program requirements may be found under the section on Interdisciplinary Programs.

Financial Support

Students who are accepted into the graduate program are provided with support from departmental training grants, departmental funds for teaching assistants, and research grants. In addition, some students bring National Science Foundation and other competitive fellowships. Through these sources, full tuition plus a stipend for living expenses are provided.

Students are encouraged to apply for outside fellowships for which they are eligible, such as the NSF Fellowships. Information regarding graduate student fellowships is available at most colleges from the career planning office.

Inquiries

Additional information regarding graduate academic programs, research activities, admissions, financial aid, and assistantships may be obtained from the Biology Education Office, Room 68-120, 617-253-3717.


The Shocking Results of TCGAP

In 2010, researchers from the University of Washington called the results of the TCGA project “sobering” and conceded, “it is becoming increasingly difficult to envision how it will be possible to develop a realistic number of targeted chemotherapies to be directed against a discrete panel of commonly mutated cancer genes.”[14]

Dr. David Agus of the University of California, the oncologist who treated Steve Jobs, even suggested in a recent speech that cancer is simply too difficult to understand and that we should stop trying.[14]

The multi-billion dollar Cancer Genome Atlas Project, a fascinating milestone in the history of cancer research, has taught us many remarkable things about cancer genetics and confirmed to us unequivocally that, above all, cancer is not a genetic disease.


Watch the video: Κληρονομικός καρκίνος μαστού (August 2022).