SAN ANTONIO—Obese breast cancer patients receiving chemotherapy have a significantly shorter overall survival (OS) than nonobese women, researchers reported.
Thomas Samuel, MD, a medical oncologist at Georgia’s Health Sciences University in Augusta, and colleagues examined the correlation between body mass index (BMI) and OS in 259 breast cancer patients receiving chemotherapy between 1997 and 2006. The investigators used data obtained from their institution’s tumor cancer registry.
Overall, 67 women had a BMI ≥35, which the World Health Organization (WHO) categorizes as class II obesity, and 192 women had a BMI <35.
Breast cancer is the most common noncutaneous malignancy and the second-leading cause of cancer-related mortality among US women, Samuel’s team noted in their poster presentation. According to the American Cancer Society, there were 209,060 new cases of breast cancer in the United States in 2010 and 40,230 deaths from the disease.
Although some studies have shown a correlation between obesity and increased breast cancer mortality, few studies have looked at the effect of BMI on prognosis in breast cancer patients receiving chemotherapy.
The study found that women who were WHO class II obese or more and received chemotherapy for breast cancer were 1.83 times more likely to die than women who have lower BMI within about 10 years of starting chemotherapy.
What’s more, OS was shortened in obese breast cancer patients receiving chemotherapy, irrespective of their race or age at diagnosis. Race and age at diagnosis are known to influence survival.
The authors cautioned that the study’s small sample size may be a possible limitation. Adjustments to chemotherapy dosing in patients with BMI ≥35 may also have altered survival outcomes.
Finally, they noted that future research will look at the effect of obesity on the biological characteristics of the breast cancer in terms of tumor size, lymph node involvement, and metastatic “potential.” Studies should also aim to examine the effect of the type and dosing of chemotherapy regimens used, estrogen receptor status, comorbidities, presence of insulin resistance with metabolic syndrome, and actual cause of death in this cohort of patients