Weight Loss

Losing Weight May Lessen Breast Cancer Risk After Menopause

Although obesity is known to raise the risk for breast cancer in postmenopausal women, new research suggests that weight loss can help mitigate this risk.

Findings from a study published in Cancer indicated that postmenopausal women with obesity who lost weight (n = 8175) had a significantly lower risk of developing breast cancer compared with those whose weight remained stable (n = 41,139).

Clinical breast oncologist Rowan T Cheblowski, MD, PhD, of the City of Hope in Duarte, California, and colleagues arrived at their conclusion after analyzing postmenopausal women from the Women’s Health Initiative Observational Study with no prior breast cancer, a normal mammogram, and available body mass index (BMI) measurements at baseline and year 3 of the study (N=61,335). Mean follow-up lasted 11.4 years.

The researchers calculated participants’ body mass index (BMI) via body weight and height measurements, classifying each participant as having lost weight (at least 5% loss), gained weight (at least 5% gain), or having a stable weight (less than 5% change) over 3 years. Self-reported intentionality was also taken into account.

The relationship between BMI change and subsequent breast cancer incidence was investigated via multivariable Cox proportional hazard regression models, revealing a total of 3061 incident breast cancers in this cohort. The hazard ratio (HR) was 0.88 for women who lost weight vs women whose weight remained stable.

Other notable findings from the study included:

  • Findings were unchanged following adjustment for mammography (HR 0.88) with no significant difference based on the intentionality of weight.
  • Although weight gain of at least 5% (n = 12,021) was not associated with breast cancer risk, it was associated with a higher incidence of triple-negative breast cancer (HRS 1.02 and 1.54, respectively).

—Christina Vogt

Reference:

Chlebowski RT, Luo J, Anderson GL, et al. Weight loss and breast cancer incidence in postmenopausal women [Published online October 8, 2018]. Cancer. https://doi.org/10.1002/cncr.31687