Certain Obese Women Have Poorer Breast Cancer Outcomes

Subtype appears to matter among obese women

Nick Mulcahy

December 09, 2010

December 9, 2010 (San Antonio, Texas) — The well-established fact that obese women with breast cancer have poorer outcomes than other women might need modification, according to the results of a retrospective study.

Only obese women with hormone-receptor-positive/HER2-negative disease had increased risks for recurrence and breast-cancer-related death in the new study, reported here at the 33rd Annual San Antonio Breast Cancer Symposium.

In short, subtype might matter among obese women with breast cancer.

Dr. Joseph Sparano

This is a novel finding, said lead author Joseph A. Sparano, MD, from the Albert Einstein Medical College and Montefiore Medical Center in Bronx, New York.

"Multiple studies" have associated obesity with breast-cancer-related mortality and with disease recurrence.

Dr. Sparano and his colleagues, in an effort to explore the relation between obesity and breast cancer outcomes, reviewed 3 Eastern Cooperative Oncology Group trials of chemotherapy: E1199, E5188, and E3189.

In their "first look," the investigators used data from the E1199 trial and found that older age (>45 years), postmenopausal status, black race, and breast-conservation surgery were all associated with obesity.

The team then took a "second look," and conducted a multivariate analysis that adjusted for variables such as age. When evaluating obese women by breast cancer subtype, they found that obese women with estrogen-receptor- and/or progesterone-receptor-positive/HER2-negative disease had significantly worse disease-free and overall survival.

Specifically, in the E1199 trial, obese women with estrogen-receptor- and/or progesterone-receptor-positive/HER2-negative disease had significantly inferior disease-free survival (hazard ratio [HR], 1.23; P = .035) and overall survival (HR, 1.46; P = .002); the effects were not seen for HER2-positive or triple-negative disease, said Dr. Sparano.

"This is obviously a disturbing dataset," said Judy Garber, MD, MPH, director of the Center for Cancer Genetics and Prevention at the Dana-Farber Cancer Institute, Boston, Massachusetts, and president-elect of the American Association for Cancer Research. She spoke at a meeting press conference.

Dr. Sparano also reported that after their initial work was done with E1199 trial data, he and his colleagues validated the findings in 2 other datasets.

"Our results may be explained by the fact that obesity is associated with hyperinsulinemia, which may drive the growth of estrogen-dependent tumors," Dr. Sparano said in a press statement.

The authors have disclosed no relevant financial relationships.

33rd Annual San Antonio Breast Cancer Symposium (SABCS): Abstract S2-1. Presented December 9, 2010.


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