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!

Sugary Beverages and Uterus (Endometrial) Cancer

cola soda Coke beverage drink

What You Need to Know: Postmenopausal women who consumed sugar-sweetened beverages were more likely to develop the most common type of endometrial cancer compared with women who did not drink sugar-sweetened beverages, according to a study published in Cancer Epidemiology, Biomarkers & Prevention, a journal of the American Association for Cancer Research.

Results: Postmenopausal women who reported the highest intake of sugar-sweetened beverages had a 78 percent increased risk for estrogen-dependent type I endometrial cancer (the most common type of this disease). This association was found in a dose-dependent manner: the more sugar-sweetened beverages a woman drank, the higher her risk.

“Although ours is the first study to show this relationship, it is not surprising to see that women who drank more sugar-sweetened beverages had a higher risk of estrogen-dependent type I endometrial cancer but not estrogen-independent type II endometrial cancer,” said Maki Inoue-Choi, Ph.D., M.S., R.D., who led this study as a research associate in the Division of Epidemiology and Community Health of the University of Minnesota School of Public Health in Minneapolis. “Other studies have shown increasing consumption of sugar-sweetened beverages has paralleled the increase in obesity. Obese women tend to have higher levels of estrogens and insulin than women of normal weight. Increased levels of estrogens and insulin are established risk factors for endometrial cancer.”

Because this study is the first to show the association between high sugar-sweetened beverage consumption and endometrial cancer, such findings need replication in other studies, according to Inoue-Choi. Inoue-Choi and colleagues used data from 23,039 postmenopausal women who reported dietary intake, demographic information, and medical history in 1986, prior to the cancer diagnosis, as part of the Iowa Women’s Health Study.

Details, details: Dietary intake was assessed using the Harvard Food Frequency Questionnaire (FFQ), which asked study participants to report intake frequency of 127 food items in the previous 12 months. A typical portion size for each food item was provided to give study participants a sense of scale. As reported in the study, the FFQ included four questions asking usual intake frequency of sugar-sweetened beverages, including 1) Coke®, Pepsi®, or other colas with sugar; 2) caffeine-free Coke®, Pepsi®, or other colas with sugar; 3) other carbonated beverages with sugar (e.g., 7-Up®); and 4) Hawaiian Punch®, lemonade, or other non-carbonated fruit drinks.

“Sugar-free soft drinks” included low-calorie caffeinated and caffeine-free cola (e.g., Pepsi-Free®), and other low-calorie carbonated beverages (e.g., Fresca®, Diet 7-Up®, and Diet Ginger Ale®). The “sweets and baked goods” category comprised 13 items in the FFQ, including chocolate, candy bars, candy without chocolate, cookies (home-baked and ready-made), brownies, doughnuts, cakes (home-baked and ready-made), sweet rolls, coffeecakes or other pastries (home-baked and ready-made), and pies (home-baked and ready-made).

The researchers categorized the sugar-sweetened beverage consumption patterns of these women into quintiles, ranging from no intake (the lowest quintile) to between 1.7 and 60.5 servings a week (the highest quintile). Between 1986 and 2010, 506 type I and 89 type II endometrial cancers were recorded among the women Inoue-Choi and colleagues studied. They did not find any association between type I or type II endometrial cancers and consumption of sugar-free soft drinks, sweets/baked goods, and starch.

“Research has documented the contribution of sugar-sweetened beverages to the obesity epidemic,” said Inoue-Choi. “Too much added sugar can boost a person’s overall calorie intake and may increase the risk of health conditions such as obesity, diabetes, heart disease, and cancer.”

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: American Association for Cancer Research (AACR) (2013, November 22). Sugar-sweetened beverage consumption increases endometrial cancer risk. ScienceDaily. Retrieved November 23, 2013, from http://www.sciencedaily.com­/releases/2013/11/131122132354.htm

Drop That Cookie: Sweet, Starchy Foods May Be Linked to Uterus Cancer

obese fat woman

The Bottom Line: Sweet, starchy foods like sugar and white bread probably are linked to endometrial cancer, while coffee probably protects against it, researchers reported on this week. But obesity is probably the #1 causative agent. These are the conclusions of the American Institute for Cancer Research (AICR) and the World Cancer Research Fund International.

The Study: The two organizations assigned an international panel of experts to review the evidence in what’s called a meta-analysis (study of studies) for what might cause various cancers. The group, which tends to focus on the links between diet, exercise and cancer, chose endometrial (uterus) cancer for the latest review.

My Take: Women who are obese have two to three times the rate of endometrial cancer. People who are more active regularly tend to have a decreased rate of endometrial cancer. the team also found some surprising findings – the degree to which coffee can protect against the cancer, and the rates at which sugary, starchy foods increase it. So, coffee in moderation is probably not a bad idea. And watch the weight!

One of the authors is spot on when she observes: “The bottom line is you want to eat whole grains instead of refined grains and sugary foods,” She adds “all the findings are really pointing to the same thing – maintaining better glucose metabolism and maintaining a healthy body weight,” she added. “That means a healthy diet and regular exercise.” That these also help reduce the risk of many, many cancers is an added bonus. Enjoy that brisk walk today!

Reference: http://www.aicr.org/assets/docs/pdf/reports/2013-cup-endometrial-cancer.pdf

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 Minuteable now: Understand Colon Cancer in 60 Minutes; Understand Brain Glioma in 60 Minutes. Thank you.