What is the role of lifestyle factors in the etiology of breast cancer?

Updated: Dec 27, 2019
  • Author: Pavani Chalasani, MD, MPH; Chief Editor: John V Kiluk, MD, FACS  more...
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Answer

The wide variability of breast cancer incidence around the world (eg, the nearly 5-fold difference between Eastern Africa and Western Europe) has long been attributed to differences in dietary intake and reproductive patterns. [45, 46, 47, 48] In general, rates differ according to the level of industrial development: there are more than 80 cases per 100,000 in developed countries, compared with fewer than 40 per 100,000 in less developed countries.

As with cancers of the colon and prostate, diets that are rich in grains, fruits, and vegetables; low in saturated fats; low in energy (calories); and low in alcohol—the more common pattern in less industrialized countries—are thought to be protective against breast cancer. [49]

One such diet is the Mediterranean diet, which comprises a high intake of plant proteins, whole grains, fish, and monounsaturated fat, as well as moderate alcohol intake and low intake of refined grains, red meat, and sweets. The Netherlands Cohort Study, which included 62,573 women aged 55-69 years with more than 20 years of follow-up, found that close adherence to a Mediterranean diet is associated with lower risk for breast cancer—in particular, for types of breast cancer that carry a poorer prognosis in postmenopausal women. [50, 51]

Compared with women who reported the least adherence to a Mediterranean diet, women who most closely adhered to the diet had a 40% reduced risk for estrogen receptor–negative (ER-) breast cancer, (hazard ratio [HR], 0.60; ptrend = 0.032) and a 39% reduced risk for progesterone receptor–negative (PR-)/ER- disease (HR, 0.61; ptrend = 0.047). The study found no significant associations with the diet and the risk of ER+ disease or total breast cancer risk. [50, 51]


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