Should doctors prescribe exercise?

“Although the data vary by different cancer types, there is a consistent trend suggesting that moderate daily exercise has a beneficial effect on preventing certain cancers. If you are a reasonably healthy adult, your should exercise regularly.” 

Let’s look at the relationship of exercise and selected cancers. The American Society of Clinical Oncology (ASCO) has done a nice job of summarizing:

Breast Cancer

While the amount of risk reduction varies among studies (20-80%), most suggest that 30 to 60 minutes of moderate to high-intensity exercise per day lowers breast cancer risk. Women who are physically active throughout their life appear to benefit the most, but those who increase physical activity after menopause also fare better than inactive women.1

Colon Cancer

Research suggests that people who increase their physical activity can lower the chance of developing colon cancer by 30 to 40% relative to sedentary adults.1,2 A decrease in colon cancer risk can be achieved regardless of body mass index (BMI) and people who are most active benefit the most. There is insufficient evidence of a protective effect of physical activity on the risk of rectal cancer (a protective effect was seen in some case-control studies, but not in cohort studies).3

Endometrial, Lung and Ovarian Cancer

A handful of studies have suggested that women who are physically active have a 20-40% reduced risk of endometrial cancer compared to those who don’t exercise.1 Higher levels of physical activity seem to also protect against lung cancer (up to 20% reduction in risk), particularly among men.1Although less consistent, research suggests that physical activity possibly reduces the risk of ovarian and prostate cancer.

What about Other Cancers?

While observational data on the benefits of exercise for prevention of the types of cancers listed above are fairly consistent, evidence of the effects of exercise on prevention of any other type of cancer either is either insufficient or inconsistent.2,4

Prostate Cancer

Prostate cancer is one disease in which the data are not consistent, however prostate cancer is a heterogeneous disease and risk factor associations for total non-aggressive disease are different from aggressive / lethal disease. Most population based studies show similar findings, with little effect of exercise on overall incidence of prostate cancer but lower risk of aggressive prostate cancers for those with the highest levels of VIGOROUS activity (rather than any type of activity). In the Health Professionals Follow-up Study men 65 years or older who engaged in vigorous physical activity, such as running, jogging, biking, swimming or tennis at least three hours per week  had a 67% lower risk of advanced prostate cancer and 74% lower risk of fatal prostate cancer.5

Conflicting data for other malignancies

For example, one recent study found no association between physical activity and risk of developing gastric, rectal, pancreatic, bladder, testicular, kidney and hematological cancers.4 In contrast, a pooled analysis of data from prospective trials with 1.4 million participants found that physical activity was linked to lower risk of 13 cancers: esophageal, lung, kidney, gastric, endometrial, myeloid leukemia, myeloma, colon, head and neck, rectal, bladder, and breast.6Interestingly, leisure-time physical activity was associated with a higher risk of melanoma (presumably due to time spent outdoors) and prostate cancer, although it is not clear from these data whether that association was with nonaggressive or aggressive prostate cancer.

While we wait for confirmation and clarity on the role of exercise in preventing all the 200+ types of cancer – should doctors prescribe exercise? The answer is simple: yes, because evidence of the protective role of exercise is already strong for some of the most common cancers.

References

  1. Lee I, Oguma Y. Physical activity. In: Schottenfeld D, Fraumeni JF, editors. Cancer Epidemiology and Prevention. 3rd ed. New York: Oxford University Press, 2006.
  2. Slattery, ML. Physical activity and colorectal cancer. Sports Medicine 2004; 34(4): 239–252.
  3. Pham NM, et al. Physical activity and colorectal cancer risk: an evaluation based on a systematic review of epidemiologic evidence among the Japanese population. Jpn J Clin Oncol. 2012 Jan;42(1):2-13.
  4. Friedenreich CM, Neilson HK, Lynch BM. Eur J Cancer. State of the epidemiological evidence on physical activity and cancer prevention. 2010 Sep;46(14):2593-604.
  5. Giovannucci E, Liu Y, Leitzmann MF, et al. A prospective study of physical activity and incident and fatal prostate cancer. Arch Intern Med. 2005; 165(9):1005-1010.
  6. 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 Intern Med. 2016 Jun 1;176(6):816-25.
  7. http://www.asco.org/about-asco/press-center/asco-resources-media/cancer-perspectives/should-cancer-doctors-prescribe?et_cid=38723632&et_rid=463715101&linkid=Read+more

I’m Dr. Michael Hunter. Of course, the disclaimer: Do not begin an exercise program without input from an appropriate medical professional. Many can simply start with a brisk walk for 30 minutes daily, 5 days per week. Have a wonderful day!

Is Soy Detrimental for Women with Breast Cancer?

What You Need to Know: Two weeks of soy supplementation was enough to increase expression of genes related to tumor proliferation.  Women with breast cancer should probably not take soy supplements, and should eat soy foods, such as tofu and tempeh, only in moderation.

The Study: Jacqueline Bromberg, M.D., Ph.D., a breast cancer specialist at the Memorial Sloan Kettering Cancer Center in New York City, and colleagues randomly assigned 140 women with newly diagnosed, early-stage breast cancer to one of two groups. In one, women took a soy protein supplement every day for anywhere from one to four weeks; those in the other group were given milk powder as a comparison. The women were premenopausal or just past menopause. The soy supplement — a powder added to water or juice — was the equivalent of about four cups of soy milk a day. Women in the study typically used it for two weeks.

Results: Researchers found that about 20 percent of the women using soy developed high blood concentrations of genistein, a soy phytoestrogen. Among those women, some showed heightened activity in certain genes that promote breast tumor growth and spread.

“This study doesn’t tell us anything about whether soy raises the risk of developing breast cancer,” said Bromberg who also noted there was no evidence of “tumor proliferation” in women with revved-up gene activity, but the study may have been too short to detect such an effect. “All we can say is that two weeks of soy supplementation was enough to increase expression of genes related to tumor proliferation.” But to be safe, she said, women with breast cancer should probably not take soy supplements, and should eat soy foods, such as tofu and tempeh, only in moderation.

My Take: There are conflicting reports on the impact of soy on breast carcinogenesis. This study examines the effects of soy supplementation on breast cancer-related genes and pathways. While the study proves little, it seems prudent (for those with a history of breast cancer) to avoid soy supplements, and to consume soy-based foods in moderation. I’m Dr. Michael Hunter.

The small print: The material presented herein is informational only, and is not designed to provide specific guidance for an individual. Please check with a valued health care provider with any questions or concerns. As for me, I am a Harvard- , Yale- and UPenn-educated radiation oncologist, and I practice in the Seattle, WA (USA) area. I feel genuinely privileged to be able to share with you. If you enjoyed today’s offering, please consider clicking the follow button at the bottom of this page.

Available now: Understand Colon Cancer in 60 Minutes; Understand Brain Glioma in 60 Minutes. Both can be found at the Apple Ibooks store. Coming Soon for iPad: Understand Breast Cancer in 60 Minutes; Understand Colon Cancer in 60 Minute; Understand Colon Cancer in 60 Minutes; Understand Brain Glioma in 60 Minutes. Thank you.

References: 1. Jacqueline Bromberg, M.D., Ph.D., physician/scientist, Memorial Sloan Kettering Cancer Center, New York City; V. Craig Jordan, Ph.D., D.Sc., scientific director, Lombardi Comprehensive Cancer Center, Georgetown University, Washington, D.C.; Sept. 4, 2014 Journal of the National Cancer Institute; 2.  http://consumer.healthday.com/cancer-information-5/breast-cancer-news-94/soy-a-friend-or-foe-of-breast-cancer-691425.html

Some Cancers More Likely Among Taller Women

What You Need to Know:  A new study has found an increased risk for certain types of cancers in taller women.

Background: While obesity has long been named as a risk factor for cancer, a new study published in Cancer Epidemiology, Biomarkers & Prevention that adjusts for various factors including age and weight, has found an increased risk for certain types of cancers in taller women.

The Evidence: The study, which included 20,298 postmenopausal women, found that for every 10-centimeter (3.94 inches) increase in height, there was a 13% increase in the risk of developing certain cancers, including, breast, colon, endometrium, kidney, ovary, rectum, thyroid, multiple myeloma and melanoma. The most surprising finding for researchers was that weight seems to be a lower risk factor than previously assumed.

“We did examine variation in risk and there was no variation of levels of risk by weight,” says senior author Thomas Rohan, PhD, MD, chairman and professor of the department of epidemiology and population health at Albert Einstein College of Medicine.

Since you can’t really do anything about your height, what does this mean to tall women? Nothing specifically, says Dr. Rohan. He says the purpose of the study was not to make clinical recommendations and there was no thought of cancer screening or diagnosis implied in the study. Rather, the researchers were merely to try to add to the existing research into the biology of cancer development.

“We have been aware of some reports in the literature about the link between cancer and height, and we thought we could make a contribution to that research,” says Dr. Rohan.

In other words, don’t try to stunt your daughter’s growth so that her cancer risk is reduced when she is in her 70s.

Lead researcher Geoffrey Kabat, PhD, MS, a senior epidemiologist at Albert Einstein College of Medicine, noted that cancer is a result of processes having to do with growth, so hormones or other growth factors that influence height may also influence long-term cancer risk. The study also notes that height should not be thought of as a risk factor, but rather as a marker for exposures that may influence cancer risk. In other words, there are so many things that effect growth, that it’s almost beyond anyone’s ability to control.

The take-home message is not to panic, but to just appreciate one more small step in the ongoing quest to try to figure out exactly what makes cancer tick. I’m Dr. Michael Hunter.

The small print: The material presented herein is informational only, and is not designed to provide specific guidance for an individual. Please check with a valued health care provider with any questions or concerns. As for me, I am a Harvard- , Yale- and UPenn-educated radiation oncologist, and I practice in the Seattle, WA (USA) area. I feel genuinely privileged to be able to share with you. If you enjoyed today’s offering, please consider clicking the follow button at the bottom of this page.

Available now: Understand Colon Cancer in 60 Minutes; Understand Brain Glioma in 60 Minutes. Both can be found at the Apple Ibooks store. Coming Soon for iPad: Understand Breast Cancer in 60 Minutes; Understand Colon Cancer in 60 Minute; Understand Colon Cancer in 60 Minutes; Understand Brain Glioma in 60 Minutes. Thank you.

Reference: http://www.prevention.com/health/health-concerns/scary-link-between-height-and-cancer-risk