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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