Should doctors prescribe exercise?

young woman running city park

“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!

How Can You Reduce Your Risk of Getting Cancer?

Recent reports suggest that about 2 out of 3 cancers may be due to “bad luck.” Today, we focus on the other third: What can you do to reduce your risk of cancer?

What You Need to Know:

  • Maintaining a healthy body weight and being physically active had the greatest impact on overall risk of a cancer-related death. 
  • Restricting alcohol consumption to one drink per day for women and two drinks per day for men was associated with 29% reduced risk for obesity-related cancers. Additionally, the risk was up to 71% lower for the most common site-specific cancers in the United States (breast, prostate, and colorectal).

Background

  • As people make their resolutions for 2015, two new studies — which show that curbing alcohol consumption, adding more plant foods to the diet, and losing excess weight can help reduce the risk of developing cancer — serve as a reminder that a healthy lifestyle is important.
  • In 1997, the World Cancer Research Fund (WCRF) and the American Institute for Cancer Research (AICR) issued cancer prevention guidelines for weight management, diet, and physical activity. These were updated in 2007 and are considered to be the most comprehensive scientific analysis of cancer prevention and causation ever undertaken. Specifically, the guidelines reported that excess body fat is associated with an increased cancer risk and that there is convincing evidence that the consumption of alcohol, red meat, and processed meat elevates cancer risk. Since that time, numerous studies have reported links between colorectal cancer risk and alcohol, between breast cancer mortality and obesity, between breast cancer relapse and obesity, and between breast cancer risk and red meat.

The Evidence: The first study, published online January 6 in Cancer Causes & Control, showed that eating a plant-based diet and limiting alcohol intake, both already included in various cancer prevention guidelines, could help cut the risk for obesity-related cancers (about a third of all of cancers). In a cohort of nearly 3000 adults, the researchers found that restricting alcohol consumption to one drink per day for women and two drinks per day for men was associated with 29% reduced risk for obesity-related cancers. Additionally, the risk was up to 71% lower for the most common site-specific cancers in the United States (breast, prostate, and colorectal). For individuals who consume starchy vegetables, such as corn, potatoes, and yams, sufficient consumption of nonstarchy legumes, fruits, and vegetables was associated with a reduction in the risk for colorectal cancer.

Pronounced Effect on Cancer Risk

In their study, Makarem and colleagues investigated whether the healthful behaviors outlined in the WCRF/AICR guidelines were associated with the risk for obesity-related cancers, in particular, breast, prostate, and colorectal cancer. Of the 2983 adults enrolled in the Framingham Offspring cohort from 1991 to 2008, the researchers identified 480 incident obesity-related cancers.

Data from food frequency questionnaires, anthropometric measures, and self-reported physical activity were used to develop a 7-component score based on recommendations for body fatness; physical activity; foods that promote weight gain; plant foods; animal foods; alcohol; and food preservation, processing, and preparation. The cohort was, on average, middle aged to older and overweight, but had a relatively high level of physical activity. The mean duration of follow-up was 11.5 years.

The overall score was not associated with obesity-related cancer risk after adjustment for confounders such as age, sex, smoking, energy, and pre-existing conditions (hazard ratio [HR], 0.94; 95% confidence interval [CI], 0.86 – 1.02). However, when the score components were considered separately, the researchers found that for every unit increment in the alcohol score (representing an improvement and more closely meeting the guideline recommendations), there was 29% lower risk for obesity-related cancers (HR, 0.71; 95 % CI, 0.51 – 0.99) and a 49% to 71% reduced risk for breast, prostate, and colorectal cancers.

Similarly, each unit increment in the subcomponent score for nonstarchy plant foods (fruits, vegetables, and legumes) for those who eat starchy vegetables was associated with a 66% lower risk for colorectal cancer (HR, 0.44; 95% CI, 0.22 – 0.88).

Healthy Body Weight and Exercise Reduce Mortality

The second study, published online January 7 in the American Journal of Clinical Nutrition, reported similar results. Researchers found that greater adherence to the cancer prevention guidelines of the American Cancer Society (ACS) was associated with a reduction not only in cancer incidence, but also in cancer mortality and total mortality.

The ACS guidelines recommend that individuals avoid smoking, achieve and maintain a healthy weight, be physically active, and eat a healthy diet that emphasizes plant foods. In their study, Geoffrey Kabat, PhD, senior epidemiologist in the Department of Epidemiology & Population Health at the Albert Einstein College of Medicine in Bronx, New York, and colleagues report that maintaining a healthy body weight and being physically active had the greatest impact on overall mortality for both men and women.

The researchers used data from the NIH-AARP Diet and Health Study, a prospective cohort study of 566,401 adults who were 50 to 71 years of age in 1995 and 1996, when they enrolled in the study. They were followed for a median of 10.5 years for cancer incidence, 12.6 years for cancer mortality, and 13.6 years for total mortality.

During the study period, there were 73,784 cases of cancer, 16,193 cancer deaths, and 81,433 deaths from any cause. The patients were stratified by how closely they adhered to ACS guidelines, and adherence to the guidelines was associated with a reduced risk for all cancers combined. When the highest level of adherence was compared with the lowest level, the hazard ratio was 0.90 for men and 0.81 for women.

In addition, increased adherence was associated with a reduction in risk for 14 of 25 specific cancers. Reduction in the risk for gallbladder cancer was 65% in men and women combined, for endometrial cancer was 60%, for liver cancer was 48% in men, for colon cancer was 48% in men and 35% in women, and for rectal cancer was 40% in men and 36% in women.

My Take: These results add to the existing evidence on the potential role of limiting alcohol intake and increasing the intake of plant foods in influencing cancer risk. Dietary advice on cancer should focus on encouraging the consumption of a plant-based diet providing abundant non-starchy fruits, vegetables, and legumes, and restricting alcohol, if consumed at all, to the recommended levels. Try to stick to the ACS Guidelines, as the closer you follow them, the greater the benefit in cancer risk-reduction. Finally, exercise and don’t use tobacco. I’m Dr. Michael Hunter.

References: Cancer Causes Control. Published online January 6, 2015. Abstract; Am J Clin Nutr. Published online January 7, 2015. Abstract; http://www.medscape.com/viewarticle/837976#vp_2

Sitting Too Long? You May Increase Your Risk of Cancer

African American young woman

What You Need to Know: If you’re spending a lot of time sitting every day, either in front of the TV or at work, you may be at higher risk for developing certain types of cancer, according to new research published this week in the Journal of the National Cancer Institute.

The Evidence: The study found an additional two hours a day of sedentary behavior was linked to an 8% increase in colon cancer risk, a 10% increase in endometrial cancer risk and a 6% increase in risk for lung cancer. It did not find the same connection for breast, rectum, ovary and prostate cancers or for non-Hodgkin lymphoma.

  • Researchers came to these conclusions by analyzing 43 existing studies – that included more than 4 million study participants and 68,936 cancer cases – to measure the relationship between hours spent sitting and certain types of cancers.
  • It’s important to note that while the study identifies a link between sedentary behavior and an increased risk for certain cancers, the research doesn’t prove cause and effect.

“Does sitting in front of the TV cause colon cancer? No,” said Dr. Martin Heslin, chief of surgical oncology at the University of Alabama at Birmingham. “But the recommendations (of the study) are awesome.” Heslin, who was not involved in the research, says that in addition to sedentary behavior, several factors can increase your risk of cancer, including drinking or smoking too much, being obese and having a genetic predisposition.

 

It’s nearly impossible to say that any one of these factors causes someone to get a specific cancer, he says, but these are the behaviors we can control to help reduce our risk.

“You can affect TV time by turning it off,” said Heslin, though he acknowledges it’s not so easy to turn off work if you’re stuck in an office all day.

In that case, Heslin suggests looking for opportunities to leave your desk, such as standing up while working or taking a walk, to reduce the number of hours you spend sitting down.

“If I ever have the opportunity to design (a meeting room), I’m putting a waist-high table in the room, and no chairs,” Heslin said.

According to an editorial accompanying the study, organizations such as the American Cancer Society and the UK Department of Public Health address the need to reduce hours spent sitting, but do not offer any quantitative recommendations or strategies to help people improve. Daniela Schmid, one of the study’s co-authors and a faculty member in the University of Regensburg’s department of epidemiology and preventive medicine, hopes to change that.

“The findings of our study may encourage public health efforts to expand physical activity recommendations to reduce time spent in sedentary behavior,” Schmid said.

Previous studies support the findings in Schmid’s study. A 2012 study conducted by the National Institutes of Health concluded that sitting for several hours a day is bad for you, even if you are physically active. Researchers found even exercising at least 150 minutes each week – the generally accepted public health guideline for physical activity – can’t reverse the negative effects of sitting down for hours. In that study, sitting increased an individual’s risk for major chronic diseases such as Type 2 diabetes, cardiovascular disease, and breast and colon cancers.

My Take: If you sit regularly, get up periodically (even if that means every 20-30 minutes for a few minutes). In addition, aim for a minimum of 150 minutes per week of the equivalent of a brisk walk (for example, 30 minutes daily for five times per week). 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: CNN Health, 16 June 2014

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.