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

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

 

 

Exercise Lowers Chances of Getting Breast Cancer

What You Need to Know: Postmenopausal women who in the past 4 years who have undertaken regular physical activity (equivalent to at least 4 hours walking per week) had a lower risk for invasive breast cancer.

The Study: Fournier and colleagues analyzed data from biennial questionnaires completed by 59,308 postmenopausal women who were enrolled in E3N, the French component of the European Prospective Investigation Into Cancer and Nutrition (EPIC) study. The mean duration of follow-up was 8.5 years, during which time 2,155 women were found to have a first primary invasive breast cancer.

Results: Postmenopausal women who in the previous 4 years had undertaken 12 or more MET-h (metabolic equivalent task-hours; roughly equivalent to at least 4 hours walking per week) had a 10% decreased risk of invasive breast cancer compared with women who were less active. 

My Take: It is not necessary to engage in vigorous or very frequent exercise; even walking 30 minutes per day seems beneficial. Keep moving, as you may reduce your own risk of cancer, diabetes, high blood pressure, heart attack, stroke, or even dementia! 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: Cancer Epidemiology, Biomarkers & Prevention 2014; doi:10.1158/1055-9965.EPI-14-0150.

 

Breast Cancer & Circadian Rhythm Disruption from Electric Lighting

woman sleeping serenely

What You Need to Know: With industrialization comes electricity to light the night, both within the home and outside of it. A convergence of research in cells, rodents, and humans suggests that the health consequences of circadian disruption may be substantial. Evidence is accumulating to suggest that exposure to light at night may present a risk for breast cancer. It is not unwise to keep your night sleep time as dark as possible.

Background: Breast cancer is the leading cause of cancer death among women worldwide. Risk is highest in economically developed countries, and is rising rapidly in places that have historically had a low risk of the disease. Until the 1980s the researchers believed that this increase might be primarily related to diet. Yet, the evidence linking fat content in the adult diet to breast cancer (and showing decreases with fruit and vegetable consumption) is rather weak. In fact, other than alcohol, overall diet composition has not been strongly associated with breast cancer risk. Body mass has been linked, however. In fact, less than half of the risk in high-risk societies can be attributed to known risk factors. While recent evidence shows that physical activity can lower risk, a decrease in such activity is not likely accountable for the additional risk found in industrialized countries. So, besides obesity, less physical activity, and the use of hormones, could increased exposure to light during the dark hours (which can disrupt the “sleep hormone” melatonin be a culprit?

breast cancer tumor

The Evidence Linking Circadian Rhythm Disruption and Breast Cancer: The first suggestion that light at night might explain a portion of the breast cancer pandemic was made in 1987. The hypothesis was based on the idea that exposure to light at night would result in melatonin suppression, which in turn would increase breast cancer risk as described in the previous section. Since 1987, a series of predictions of this theory have been tested. Let’s turn to some of the evidence:

  • Shift work: Women who work nights (shift work) are at higher risk of breast cancer. The International Agency for Research on Cancer concluded that “shift work that includes circadian rhythm disruption is probably carcinogenic to humans.” The American Medical Association then broadened the topic in 2012 on the health habits of light at night in general. While subsequent studies have had mixed results, a meta-analysis (including a study of high-quality studies) linked night work to an increased risk (by a factor of 1.4).
  • Blind women: Four studies have suggested that blind women may be at a lower risk of breast cancer than sighted women.
  • Ecological analyses: Kloog analyzed cancers (lung, colon, larynx, and liver) in 164 countries. Breast cancer was significantly associated with nighttime illumination, and it was estimated that the risk was increased by a factor of 1.3 to 1.5, compared with the lowest lighted countries. The investigators controlled for fertility rate, per capita income, percent of urban population, and electricity consumption.
  • Genetics (circadian gene polymorphisms): Researchers first linked a circadian gene polymorphism to breast cancer risk in 2005.
  • Differences in methylation of circadian genes have been found when comparing day shift and night shift workers, offering a possible mechanism for an increased risk among night workers.

My Take: It is clear that electric lighting, including indoor evening light levels, has strong effects on our circadian rhythms. Recent studies show that the lighting used in at the typical home (in the industrialized world) is enough to delay melatonin onset and blunt its night peak. So here is what I would like you to do:

  • Limit your night exposure to light, whether from computer screens (the emitted light in the blue spectrum changes melatonin levels) or to night lights.
  • Sleep in a dark room, if possible (no light from the clock next to the bed, or seeping into your room from street lights, for example). Nocturnal light exposure and circadian disruption may be particularly important for children, and even exposure to light as a pregnant woman may affect fetal exposure to hormone levels in utero.

So many questions remain: Might circadian rhythm disruption affect your response to chemotherapy? Could it affect the natural history of breast cancer and affect the risk or pace of progression? Can we control our lighting in a more sophisticated fashion that might not be so disruptive? I’m Dr. Michael Hunter, and I thank you for reading this very long blog.

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: RG Stevens et al. Breast Cnacer and Cricadian Disruption from Electric Lighting in the Modern World. CA Cancer J Clin 2014;64: 207-218.