Weight May Not Affect Breast Cancer Survival

Luminal breast cancer survival not impacted by BMI among women taking antiestrogen medications

(RxWiki News) We’ve been told time and again that fat kills. Being overweight or obese definitely adds to our risks of developing chronic diseases including cancer. A new study finds, though, that it doesn’t appear to impact cancer survival.

Contrary to current beliefs, a woman’s weight apparently doesn’t affect how long she will live after being treated for one type of breast cancer. Body mass index (BMI) did not affect long-term risks for women with estrogen receptor positive (ER+) breast cancer taking estrogen-blocking therapies.

This study looked at the effectiveness of tamoxifen and letrozole (Femara) in keeping breast cancer under control. This is a follow-up of the trial that’s been under way since 1998.

"Ask your oncologist about adjuvant therapy."

For this study, researchers recruited just over 8,000 women with ER+ breast cancer to participate in the Breast International Group (BIG) 1-98 trial. A baseline BMI was taken. This is a calculation based on a person’s height and weight. Overweight is a BMI of 25 kg/m2 and obesity starts at 30 kg/m2.

Marianne Ewertz, MD, of the department of oncology at the Odense University Hospital and University of Southern Denmark, led the research team.

The final participants included 4,760 women who were randomly assigned to take either tamoxifen or letrozole (Femara) for five years. Researchers also examined the effects of sequential treatment – taking one drug for two years, followed by three years of the other.

After 8.7 years of follow-up, 17 percent of the women had died. There was only a slight increase in deaths among women who were obese compared to normal weight women. No difference in survival was seen in women who were overweight vs. those who were not.

The authors concluded, “There was no evidence that the benefit of letrozole over tamoxifen differed according to patients' BMI.”

Breast cancer specialist, Adam Brufsky, MD, PhD told dailyRx News, "This is interesting in that, in some studies, being overweight seems to decrease survival, but in this study there was no effect."

"As physicians we would still recommend trying to eat a healthy diet, get a modest amount of exercise weekly, and keep weight under modest control as the best steps to try to prevent cancer recurrence," said Dr. Brufsky, who is a professor of medicine at the University of Pittsburgh.

As seen in the five-year follow-up, letrozole was more effective than tamoxifen in all women, regardless of BMI. Women taking this medication, which is part of a class of drugs called aromatase inhibitors, are living longer and have fewer recurrences and metastases (spreading) of the disease than women taking tamoxifen.

This research appeared in the November issue of the Journal of Clinical Oncology.

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Review Date: 
January 3, 2013