Wednesday, May 20, 2015

Modest Weight Gain Increases Breast Cancer Risk in Premenopausal Women

by Graham A. Colditz, MD, DrPH

In a recent detailed analysis of weight change across the life course (funded by our NCI TREC center addressing obesity and cancer), we reported that short-term weight gain, defined as change over a 4-year time frame, significantly increased risk of both premenopausal and postmenopausal breast cancer (see report for free download – link here)(1). Previous literature has largely focused on weight gain and weight loss in relation to postmenopausal breast cancer. Here, for the first time, we draw out detailed categories of weight change and consider change over 4 years and risk of breast cancer in the next 2-year interval of follow-up. While our TREC funded data analysis was ongoing and we were writing our manuscript a new report from Europe addressed weight change over approximately 4.7 years and subsequent risk of breast cancer.(2) That study had fewer premenopausal breast cancer cases than we had, but found largely similar results for short-term weight gain and increased risk of breast cancer. 

With 736 premenopausal breast cancer cases in the Nurses’ Health Study, we show that a weight gain of 10 or more pounds in just 4 years is associated with significantly higher risk of breast cancer in the subsequent years after the weight gain. Why does this matter? Well, lots of women gain weight through their premenopausal years. Based on previous findings, it's likely many of these women did not think that this could impact their risk of breast cancer? Here we show that short-term gain does increase risk, and that this risk is more important for receptor negative (that is ER-ve PR-ve) breast cancer – the type that is more common in premenopausal women and the type for which we don't have effective treatments. Weight gain of 10 or more pounds in 4 years during premenopausal life, more than doubles risk of this hard to treat type of breast cancer. In additional analyses, we observed that the adverse effect of weight gain was present among premenopausal women regardless of their starting BMI (body mass index), a measure of adiposity. Normal weight and overweight women all experienced the increase in risk of breast cancer.

In context, the majority of epidemiologic studies of breast cancer have focused on postmenopausal breast cancer. Fully 75 percent of breast cancer is diagnosed after menopause. On the other hand, waiting until menopause to begin screening (early detection) and to consider prevention strategies for higher risk women, misses any hope of prevention for the almost 1 in 4 breast cancers diagnosed before age 50. Weight gain in the premenopausal years may be contributing importantly to the burden of premenopausal disease. Furthermore, in Asia, rates of premenopausal breast cancer are rapidly rising. They are now approaching the rates in the US for women of similar ages.(3) ER-negative breast cancer is more common in premenopausal women – representing 30% of breast cancer diagnosed among women 35 to 44 but only about 12% among women age 65 and older.(4)

Global data attest to the growing obesity epidemic among women and men around the world. One consequence of this weight gain in women through their early adult years now looks to be increased breast cancer. As low and middle income countries develop, they also transition to higher rates of breast cancer. Adding strategies to prevent premenopausal breast cancer remains our highest priority, as this cancer has the highest societal burden, being diagnosed among women in their peak years of work productivity and family care.

The good news is that we can avoid weight gain through increasing physical activity and making healthier food choices.

Tips
  • Integrate physical activity and movement into your life.
  • Eat a diet rich in fruits, vegetables and whole grains.
  • Choose smaller portions and eat more slowly.
  • Use your bathroom scale regularly, so you keep surprise weight gain at bay.
  • Get a pedometer and work up to 10,000 or more steps per day.
For Parents and Grandparents
  • Limit children’s TV and computer time.
  • Encourage healthy snacking on fruits and vegetables.
  • Encourage activity during free time.
For more weight control tips, visit our colleagues' site at the Harvard School of Public Health: The Nutrition Source.

References

1. Rosner B, Eliassen AH, Toriola AT, Hankinson SE, Willett WC, Natarajan L, Colditz GA. Short-term weight gain and breast cancer risk by hormone receptor classification among pre- and postmenopausal women. Breast cancer research and treatment. 2015;150(3):643-53. doi: 10.1007/s10549-015-3344-0. PubMed PMID: 25796612; PMCID: 4383816.

2. Emaus MJ, van Gils CH, Bakker MF, Bisschop CN, Monninkhof EM, Bueno-de-Mesquita HB, Travier N, Berentzen TL, Overvad K, Tjonneland A, Romieu I, Rinaldi S, Chajes V, Gunter MJ, Clavel-Chapelon F, Fagherazzi G, Mesrine S, Chang-Claude J, Kaaks R, Boeing H, Aleksandrova K, Trichopoulou A, Naska A, Orfanos P, Palli D, Agnoli C, Tumino R, Vineis P, Mattiello A, Braaten T, Borch KB, Lund E, Menendez V, Sanchez MJ, Navarro C, Barricarte A, Amiano P, Sund M, Andersson A, Borgquist S, Olsson A, Khaw KT, Wareham N, Travis RC, Riboli E, Peeters PH, May AM. Weight change in middle adulthood and breast cancer risk in the EPIC-PANACEA study. Int J Cancer. 2014. doi: 10.1002/ijc.28926. PubMed PMID: 24771551.

3. Jung KW, Won YJ, Kong HJ, Oh CM, Seo HG, Lee JS. Prediction of cancer incidence and mortality in Korea, 2013. Cancer research and treatment : official journal of Korean Cancer Association. 2013;45(1):15-21. doi: 10.4143/crt.2013.45.1.15. PubMed PMID: 23613666; PMCID: 3629359.

4. Colditz GA, Rosner BA, Chen WY, Holmes MD, Hankinson SE. Risk factors for breast cancer according to estrogen and progesterone receptor status. Journal of the National Cancer Institute. 2004;96(3):218-28. Epub 2004/02/05. PubMed PMID: 14759989.



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