In early-stage breast cancer, obesity is linked to worse outcomes, including shorter time to recurrence (TTR), disease-free survival (DFS) and overall survival (OS). In one instance, though, obesity was protective against the disease.
"Stay active to stay slim."
Lead researcher Sao Jiralerspong, M.D., Ph.D., an assistant professor of medicine at Baylor College of Medicine, used data from the Lester and Sue Smith Breast Center at Baylor to explore the link between weight and treatment types in 4,368 breast cancer patients treated between 1970 and 1995.
Looking at the group as a whole, researchers found overweight individuals had the same outcomes as patients of normal weight. But obese patients had higher risks for worse TTR, DFS and OS.
Obese patients who did not have adjuvant (after surgery) chemotherapy or endocrine therapy (such as tamoxifen), also tended to have worse survival outcomes compared to normal-weight patients.
Patients who were obese and had chemotherapy also had poorer outcomes than patients whose weight was normal. Obesity, in fact, almost eliminated the expected benefit of the chemotherapy.
There was one exception. Obese patients who were on endocrine therapy - primarily tamoxifen - had significantly better outcomes than normal-weight patients.
This finding surprised Dr. Jiralerspong, who said further study is needed to explain this phenomenon.
He thinks the link between excess weight and poorer outcomes has to do with such biological factors as inflammation, higher blood insulin levels and growth factors secreted by fat cells.
In an interview with dailyRx, Graham A. Colditz, M.D., Dr.P.H., Niess-Gain Professor of Surgery at Washington University School of Medicine, said, "These data confirm longstanding understanding of obesity and poor survival after breast cancer. In 1990, Ralph Coates and colleagues published survival data showing such a relationship," Dr. Colditz said.
He continued. "Despite improved access to care and adherence to standard therapy, the poor outcome among obese women with breast cancer persists. These data also support ongoing randomized controlled trials of weight loss after breast cancer as an adjunct to standard therapy. One such trial, ENERGY, is recruiting breast anger survivors in San Diego, Denver, Birmingham, ad St Louis"
Dr. Colditz concluded, "Given the consistent evidence that obesity leads to poor outcomes after breast cancer, greater emphasis on weight loss and increases in physical activity for survivors is urgently needed."
These findings were reported at the 2011 CTRC-AACR San Antonio Breast Cancer Symposium.