Which environmental factors increase the risk for breast cancer?

Updated: Feb 04, 2021
  • Author: Pavani Chalasani, MD, MPH; Chief Editor: John V Kiluk, MD, FACS  more...
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A number of environmental exposures have been investigated in relation to breast cancer risk in humans, including the following [58, 59, 60, 61] :

  • Tobacco smoke (both active and passive exposure)

  • Dietary (eg, charred and processed meats)

  • Alcohol consumption

  • Environmental carcinogens (eg, exposure to pesticides, radiation, and environmental and dietary estrogens)

Of these environmental exposures, only high doses of ionizing radiation to the chest area, particularly during puberty, have been unequivocally linked with an increased risk of breast cancer in adulthood. [61, 62] Because of the strong association between ionizing radiation exposure and breast cancer risk, medical diagnostic procedures are performed in such a way as to minimize exposure to the chest area, particularly during adolescence.

Women with a history of radiation exposure to the chest area should be examined and counseled regarding their risk of breast cancer on the basis of the timing and dose of the previous exposure. A patient treated for Hodgkin lymphoma with Mantel radiation that includes the breasts in the radiation field has a 5-fold higher risk of developing breast cancer. This risk increases markedly for women treated during adolescence [63] ; evidence suggests that cumulative risk increases with age as a function of age of exposure and type of therapy. [64]

A meta-analysis by Yuan et al found an increased risk of breast cancer in women who do long-term night shift work.  In North America and Europe, working the night shift was associated with a 32% increased risk for breast cancer overall (odds ratio [OR], 1.316). Risk increased in a dose-response fashion, rising 3.3% (OR, 1.033) Risk was even higher for nurses (OR, 1.577). [65]

Current evidence does not support a significant and reproducible link between other environmental exposures and breast cancer risk. Thus, a number of factors remain suspect but unproven.

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