Obesity Associated With Risk of Dissimilar Breast Cancers

March 24, 2011
OBGYN.net Staff

High body mass index (BMI) and low levels of physical activity are associated with increased risk of triple-negative and estrogen receptor-positive (ER+) breast cancers in postmenopausal women, according to a study published online March 1 in Cancer Epidemiology, Biomarkers & Prevention.

WEDNESDAY, March 2 (HealthDay News) -- High body mass index (BMI) and low levels of physical activity are associated with increased risk of triple-negative and estrogen receptor-positive (ER+) breast cancers in postmenopausal women, according to a study published online March 1 in Cancer Epidemiology, Biomarkers & Prevention.

Amanda I. Phipps, from the Fred Hutchinson Cancer Research Center in Seattle, and colleagues analyzed data from 155,723 women enrolled in the Women's Health Initiative, of whom 307 had triple-negative breast cancer and 2,610 had ER+ breast cancer. Baseline BMI, BMI earlier in adulthood, waist and hip circumference, and physical activity were analyzed to determine if they were associated with the risk of triple-negative and ER+ breast cancers.

The researchers found that women with BMI in the highest quartile had a 35 percent increased risk of developing triple-negative breast cancers compared to those in the lowest quartile, and a 39 percent increased risk of developing ER+ breast cancers. Waist and hip circumferences showed a positive association with ER+, but not with triple-negative breast cancer. Women who reported rates of physical activity in the highest tertile had a 23 percent decreased risk of triple-negative breast cancer and a 15 percent decreased risk of ER+ breast cancer.

"The results of this analysis suggest the existence of modest but modifiable risk factors for postmenopausal triple-negative breast cancer," the authors write. "These factors were similarly associated with lower risk of ER+ breast cancer, suggesting that the protective effects of these exposures are not breast cancer subtype-specific."

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