Exercise and premenopausal breast cancer risk

Most studies to date conclude that exercise reduces breast cancer risk, and even more so for postmenopausal women. Until more recently, this process has not been as well-studied in pre-menopausal women. Understanding the connection between exercise and hormone balance may allow women to take a more proactive approach to lowering their risk over time. 

In the past 15 years and after imaging thousands of women of all ages with medical infrared imaging (MIR) or thermography, I have frequently observed this possible correlation between exercise and risk, based on thermography’s role as a physiological test, thus having the ability to provide valuable and unique information related to hormone balance in the breast tissue to patients and their health care providers. Thermography can detect thermovascular activity secondary to levels of estrogen in the breast. With thermography it is also possible to monitor the effects of treatment and/or lifestyle changes over time, that may play a significant role in breast cancer prevention.

It is widely accepted that exercise improves aerobic fitness, increases lean body mass, and lowers body fat. Furthermore, is an established fact that our exposure to estrogen over time is associated with increased breast cancer risk. 

One mechanism of how exercise may affect breast cancer risk is through exercise’s possible role in healthy estrogen metabolism, as the researchers found in this 2013 study on the Effects of Aerobic Exercise on Estrogen Metabolism in Healthy Premenopausal Women in Cancer Epidemiol Biomarkers Prev. (1) 

Previous prospective studies involving premenopausal women have supported the theory that the estrogen metabolite pathway favoring 2-hydroxylation over the 16α-hydroxylation is associated with a lower risk of invasive breast cancer. (2) In simpler terms, breaking estrogen down to the “good” form of estrogen equates to lower risk and breaking estrogen down to the “bad” form of estrogen equates to higher risk. In fact, estrogen metabolism is increasingly being recognized as a risk factor for both breast and prostate cancer. (3,4)

The more recent 2013 study proposed that since women can both produce and break down estrogen in their fat cells, exercise may affect estrogen metabolism and in turn, modulate breast cancer risk. This randomized study evaluated estrogen metabolism of approximately 300 healthy, eumenorrheic women over 16 weeks. It compared these results of a group of sedentary premenopausal women moderately-to vigorously exercising 30 minutes 5 days a week to those of a group of sedentary women not engaging in exercise.

At the end of the study, the exercising cohort’s ratio of 2-OHE1/16α OHE1 in urine increased significantly. This adds to the hypothesis that higher urine concentrations of 2-OHE1 (good estrogen metabolite) and higher ratios of 2-OHE1/16α OHE1 may have a protective benefit against breast cancer in healthy, pre-menopausal women. In conclusion, pre-menopausal women may have another tool in their arsenal to help lower their risk for breast cancer, and perhaps breast thermography may offer another adjunctive tool regarding hormone balance, risk assessment and to help monitor changes over time.

In my next post on our thermography blog, I will discuss other possible ways to promote healthy estrogen metabolism through diet and/or supplementation.

  1. Smith AJ, Phipps WR, Thomas W, Schmitz KH, Kurzer MS. The effects of aerobic exercise on estrogen metabolism in healthy premenopausal women. Cancer Epidemiol Biomarkers Prev. 2013;22(5):756‐764. doi:10.1158/1055- 9965.EPI-12-1325.
  1. Muti, Paola, et al. “Estrogen Metabolism and Risk of Breast Cancer: A Prospective Study of the 2:16α-Hydroxyestrone Ratio in Premenopausal and Postmenopausal Women.” Epidemiology, vol. 11, no. 6, 2000, pp. 635–640.
  1. 640. JSTORwww.jstor.org/stable/3703815. Hamilton-Reeves JM, Rebello SA, Thomas W, Slaton JW, Kurzer MS. Soy protein isolate increases urinary estrogens and the ratio of 2:16alpha- hydroxyestrone in men at high risk of prostate cancer. J Nutr. 2007; 137(10):2258-2263.
  1. Carruba G. Estrogen and prostate cancer: An eclipsed truth in an androgen-
    dominated scenario. J Cell Biochem. 2007; 102(4):899-911.