If we know the potential risks of certain lifestyle behaviors on developing breast cancer, we can better understand and choose preventative measures that can reduce our risk.
There is increasing evidence that the risk of developing breast cancer is influenced by certain dietary and environmental factors. Breast cancer remains the leading cause of cancer deaths for non-smoking women. Of the 200,000 women diagnosed yearly, 44,000 American women die and incidence is increasing worldwide. There has also been a notable increase in aggressive cancers in young women (under 40 years old). About 2.5 million women are breast cancer survivors. Only 5-10% of breast cancers diagnosed yearly are related to breast cancer genetic abnormalities. The rest of the cancers have an unknown causes.
Current evidence about risks that we can influence
Understanding the interaction between nutrition, the environment and epigenetics (heritable changes in gene expression) is critical when developing lifestyle strategies for maintaining health. There is increasing evidence that dietary and environmental factors influence early stages of mammary gland development, beginning in utero and throughout our lifecycle, suggesting a persistent potential influence on gene expression and future breast cancer risk.
Review of Nutrition Research on Breast Cancer
Women who follow a traditional Mediterranean diet appear to have a lower risk of developing breast cancer after menopause than women with different eating habits. Researchers found that among 14,800 Greek women followed for a decade, those who kept most closely to the region’s traditional diet were less likely to be diagnosed with breast cancer than those whose eating habits were least Mediterranean-like. In general, the Mediterranean diet is rich in fish, olive oil, vegetables, whole grains, nuts and legumes, and relatively low in red meat and dairy.
According to researchers at the Moores Cancer Center at the University of California, San Diego (UCSD), in a study published in the journal Nutrition Review, the relationship between vitamin D3 serum levels and the risk of colon and breast cancer across the globe has estimated that 600,000 cases of breast and colorectal cancer could be prevented each year worldwide with adequate levels of vitamin D.
Another study looking at Vitamin D and breast cancer risk appeared in the Journal of the American College of Surgeons, November 2012 issue. 338 women living in Marin County, Ca where breast cancer risk is one of highest in the nation, were studied using mouth cells for genetic variations (called SNPs). The researchers found that women who were at high risk for breast cancer were 1.9 times more likely to have a specific vitamin D receptor variation (Vitamin D Receptor Apa1 A2/A2 homozygous polymorphism) than the general population. Vitamin D3 is available through diet, supplements and exposure of the skin to sunlight.
Multiple studies have found that increasing consumption of fruits and vegetables protects against the development of breast cancer. This protective effect (of fruit and vegetable consumption) may be due in part to the high fiber content and nutrient density of these foods. Compounds in fruits and vegetables that have antioxidant and cancer protective activity include lignans, indole-3-carbinol, sulfurophane (broccoli family), glucosinolates, allium compounds (garlic and onion family), isoflavones, isothiocyanates, protease inhibitors, saponins, and flavonoids.
Dietary Fiber, fermented by the human gut flora results in the formation of short-chain fatty acids (SCFAs). Research suggests that the SCFAs may activate detoxifying and antioxidative enzymes. Some researchers propose that the induction of glutathione S-transferases by SCFAs may contribute to the detoxification of dietary carcinogens, many implicated in breast cancer studies.
Detoxification is the biochemical process that transforms non-water-soluble toxins and metabolites into water-soluble compounds that can be excreted in urine, sweat, bile or stool. In order to optimize detoxification, nutrients, precursors and enzymatic cofactors must be constantly replenished and both phase I and phase II liver pathways must be supported by vitamins, fiber, probiotics, proteins, and antioxidants. For example, Glutathione is an antioxidant compound synthesized from the precursor amino acids glutamate, cysteine and glycine. It is mainly involved in detoxification mechanisms of xenobiotics (foreign chemicals) and carcinogens through conjugation reactions via the enzyme glutathione transferase. Heavy metals such as mercury are removed from the body by conjugation with glutathione. Numerous substances have been shown to support glutathione levels in addition to the amino acid precursors including N-acetyl cysteine (NAC), S-adenosyl-methionine (SAMe), milk thistle and vitamin C.
Carbohydrates in our diets affect the body’s levels of blood glucose (blood sugar) and the hormone insulin. Several lines of evidence suggest that insulin levels may directly or indirectly affect breast cancer risk. This hypothesis has prompted research on dietary carbohydrates and their possible relationship to breast cancer risk. Dietary recommendations include avoidance of refined carbohydrates and simple sugars. Recommendations are that carbohydrates are derived from whole grains, fruits, vegetables and other high fiber foods that make up a healthful diet.
Review of the recent literature on Lifestyle and Breast Cancer:
A study in the journal Cancer, demonstrated that moderate exercise may help to reduce risks for breast cancer. The researchers found that both pre and post menopausal women who reported exercising between 10 and 19 hours each week had a 30 percent lower risk, the greatest decrease in the study. Even women who exercised less than that had a decrease in breast cancer risk. Results were most pronounced for postmenopausal women and for hormone-receptor positive breast cancer.
Being overweight is associated with an increased risk of developing breast cancer. It has been estimated that excess body weight accounts for about 5% of all cancers in Europe. Maintaining an ideal body weight is therefore recommended. Being overweight could lead to worse outcomes from breast cancer, according to a study published August, 2012 in the journal Cancer. Specifically, the study showed that overweight women who have been treated for breast cancer have a higher risk of recurrence. Post-menopausal women who have type 2 diabetes may raise their risk of breast cancer, according to a review conducted by the International Prevention Research Institute.Stress
The relationships between objective and subjective stresses, social support and survival from breast cancer have been studied over the years. Support groups and the importance of examining positive responses to traumatic events, growth, appreciation of life, shift in priorities, have led to studying long term effects and benefits of this intervention for reducing perceived stress and social support. A study from UCLA in Sept. 2010 in the journal Cancer Research revealed that chronic stress acted an accelerant for breast cancer cell spread. In this animal study, researchers found that the stressed mice had a 30-fold increase in metastasized cancer cells compared to those mice that weren’t stressed. The study also found the biological mechanism that caused the difference was reprogramming of immune cells call macrophages, to act aggressively instead of protectively. Remarkably, the researchers found they were able to block these effects by treating the stressed mice with drugs called beta-blockers that blocked the nervous system’s reprogramming of the immune cells causing the metastasis.
There is evidence for DNA damage due to chronic psychological stress and stress hormones, according to a Sept, 2012 article in Breast Cancer Research. Although there has been some evidence of this occurring, the mechanism by which it occurs had not been known. Dr. Hara and her colleagues now have evidence that chronic stress acts through the beta-adrenergic nervous system to stimulate two pathways that result in the accumulation of DNA damage.
A research team from UH Case Medical Center presented evidence that less sleep was strongly associated with increased aggressive metastasis in post-menopausal women with breast cancer, but not pre-menopausal women. By reviewing medical records and patients surveys, the researchers found this correlation which makes sleep duration important not only to heart disease, diabetes, and obesity, but now to breast cancer. The sleep duration associated with risk was for women who regularly sleep six hours or less. Dr. Li, MD, PhD, a study co-author and family medicine physician in the Department of Family Medicine at UH Case Medical Center and Associate Professor of Family Medicine, Epidemiology and Biostatistics at Case Western Reserve University School of Medicine says, “effective intervention to increase duration of sleep and improve quality of sleep could be an under-appreciated avenue for reducing the risk of developing more aggressive breast cancers and recurrence.”
Breast cancer patients who practice yoga experience lower stress and improved quality of life compared to counterparts who do stretching exercises. Researchers at the University of Texas MD Anderson Cancer Center studied 163 women with an average age of 52 who were undergoing radiation therapy for breast cancer, ranging from early onset to stage three. Women in the yoga and stretching groups each reported less fatigue than the non-exercise group. Women who did yoga reported “greater benefits to physical functioning and general health and were more likely to perceive positive life changes from their cancer experience than either other group.” The yoga group also saw the “steepest decline in their cortisol across the day, indicating that yoga had the ability to regulate this stress hormone,” the study found[. According to researchers, “this is particularly important because higher stress hormone levels throughout the day, known as a blunted circadian cortisol rhythm, have been linked to worse outcomes in breast cancer.” The researchers are working on a phase III clinical trial to further study how yoga may lead to better physical functioning in breast cancer patients.
A study in JAMA in Nov. 2011, studied women with invasive breast cancer and found that drinking only 3-6 glasses of wine/ week increased risk about 15%. Women who had 2 drinks/day had an increased risk of 51%. Binge drinking, but not frequency of drinking, was also associated with breast cancer risk after controlling for cumulative alcohol intake. Some experts have estimated that risk increases 10% for each additional drink/day. According to the site Breastcancer.org, alcohol can increase levels of estrogen and other hormones associated with hormone-receptor-positive breast cancer. Alcohol also may increase breast cancer risk by damaging DNA in cells. Teen and tween girls aged 9 to 15 who drink three to five drinks a week have three times the risk of developing benign breast lumps. (Certain categories of non-cancerous breast lumps are associated with a higher risk of breast cancer later in life.)
While only a few studies have been done on drinking alcohol and the risk of recurrence, a 2009 study found that drinking even a few alcoholic beverages per week (three to four drinks) increased the risk of breast cancer coming back in women who’d been diagnosed with early-stage disease. The bottom line is that regularly drinking alcohol can harm your health, even if you don’t binge drink or get drunk. All types of alcohol count. One drink equals 12 ounces of beer, 5 ounces of wine, or 1.5 ounces of hard liquor.
A study presented in April, 2012 at the annual meeting of the American Society for Biochemistry and Molecular Biology, may have found at least one mechanism to explain the link between alcohol consumption and breast cancer. Dr. Rodriguez-Fragoso and her group think that they have found the connection with a protein called CYP2E1. CYP2E1 is found in breast cells known as mammary epithelial cells, which are also where most breast cancers originate. The researchers believe that this may influence breast cancer development. They administered alcohol to separate cultures of breast cells from healthy breast tissue (from women undergoing breast plastic surgery) that had varying levels of CYP2E1. Cells that expressed low levels of CYP2E1 were mostly not affected by the effects of the alcohol treatment but cells with increased amounts of CYP2E1 protein were greatly affected, suggesting that women with higher expression levels of the protein would show similar responses. Dr. Rodriguez-Fragoso stated, “this means that each individual will have a different response to alcohol, and each should take different precautions to minimize their risk of developing breast cancer”. Dr. Rodriguez-Fragoso felt that her group would be able to develop a means of diagnosis that would determine the expression levels of CYP2E1 in breast tissue.
A research study at California Pacific Medical Center Research Institute and published in the journal, Molecular Cancer Therapeutics, found a compound in cannabis that may prove to be effective in helping stop the spread of breast cancer cells throughout the body. The compound, CBD, could be the first non-toxic agent to show promise in treating metastatic forms of breast cancer. Sean D. McAllister, Ph.D., a cancer researcher at CPMCRI and the lead author of the study states, “Right now we have a limited range of options in treating aggressive forms of cancer. Those treatments, such as chemotherapy, can be effective but they can also be extremely toxic and difficult for patients. This compound offers the hope of a non-toxic therapy that could achieve the same results without any of the painful side effects.” The researchers used CBD to inhibit the activity of a gene called Id-1, which is believed to be responsible for the aggressive spread of cancer cells throughout the body, away from the original tumor site. The researchers point out that while their findings are promising, they are not a recommendation for people with breast cancer to smoke marijuana. They say it is highly unlikely that effective concentrations of CBD would be reached by smoking cannabis. While CBD is not considered psychoactive, it is still a controlled drug.
In this issue we wanted to review some lifestyle research so we can consider making the changes in our daily lives that we can control. We have often written about environmental exposures that are associated with increasing breast cancer risks. As we learn more and begin to reduce our exposures, and advocate locally for healthy environments, we will continue to keep our readers updated on the latest research, news, and information so that we may all be healthy!