Iâ€™m a huge advocate of the Sister Study, as it has the potential to teach us important information about how environmental and genetic factors may affect a womanâ€™s chances of getting breast cancer.
The Sister Study, which is being conducted by the National Institute of Environmental Health Sciences, is the first-ever long-term study in the United States and Puerto Rico of women ages 35 to 74 whose sisters had breast cancer. The study has enrolled 50,000 women and will follow them for at least 10 years in an attempt to identify factors associated with developing breast cancer.
And now, the first findings from the Sister Study are in. Results of two pilot studies were published recently in the journal Cancer, Epidemiology, Biomarkers and Prevention. Taken together, they indicateâ€”and reinforce my beliefâ€”that a healthy lifestyle can go a long way toward reducing breast cancer risk. (This doesnâ€™t mean that if you have a healthy lifestyle you will not get breast cancer. There are many women who have done everything â€œrightâ€ who still develop the disease. But it does mean that it can help reduce your risk.)
The studies showed that women who maintain a healthy weight and who didnâ€™t experience a lot of stress were less likely to have certain chromosomal changes that are associated with aging than were women who were overweight and stressed. These chromosomal changes were examined by studying telomeres, which cap the ends of the chromosomes. (Each chromosome looks like an X, and there is a telomere on each endpoint, sort of like the plastic pieces at the end of your shoelaces. They protect the cell from losing important genes during cell replication in much the same way the plastic ends on your shoelaces prevent the string from unraveling.)
Every time a cell reproduces, a piece of the telomere gets clipped off until there is virtually nothing left. When the telomere is too short to continue functioning, it sends the cell a message that it is now time to die. Cancer cells have an enzyme that reattaches the clipped off piece, which fools the cell into thinking it is younger than it is … plastic surgery for the telomere? This is one reason cancer cells keep growing without the natural brake.
One of the studies found that women who were overweight during their 30s, and were still overweight today, had shorter telomeres than those who became overweight after their 30. This finding suggests that obesity accelerates the aging process. The second study looked at the association between telomere length and perceived stress levels. It also found that stress also appears to impact telomere length. In fact, as Christine Parks, Ph.D., an NIEHS epidemiologist and lead author on the paper, noted, “Among women with both higher perceived stress and elevated levels of the stress hormone epinephrine, the difference in telomere length was equivalent to or greater than the effects of being obese, smoking, or 10 years of aging.”
Because the Sister Study is an epidemiological study, it can only show correlations. It canâ€™t prove cause and effect. This means it canâ€™t definitively tell us that stress and obesity cause cancer. But the fact that both of these pilot studies showed that being overweight and experiencing a lot of stress appear to be linked to shorter telomeres is an interesting finding. Itâ€™s also one that supports previous findings that have shown correlations between stress and obesity and breast cancer risk.
Even better, itâ€™s something you can act on by introducing exercise into your daily routine. A little bit of exercise can go a long way toward both helping you lose weight and reduce stress. So, get off the Internet (after youâ€™re done reading my blog!) and go for a walk. Your telomeres will thank you!
Kim S, Parks CG, DeRoo LA., Chen, H, Taylor JA, Cawthon RM, Sandler DP. Obesity and Weight Gain in Adulthood and Telomere Length. Cancer Epidemiology Biomarkers & Prevention 2009;18(3):816-20 March 2009.
Parks CG, Miller DB, McCanlies EC, Cawthon RM, Andrew ME, DeRoo LA, Sandler, DP. Telomere Length, Current Perceived Stress, and Urinary Stress Hormones in Women. Cancer Epidemiology Biomarkers & Prevention 2009; 18(2): 551-560. February 2009.