Obese women with breast cancer have lower rates of survival, and suffer a more intense form of the disease, according to recently-published research.
"The more obese a patient is, the more aggressive the disease," said Massimo Cristofanilli, MD, associate professor of medicine in the Department of Breast Medical Oncology at The University of Texas M.D. Anderson Cancer Center. "We are learning that the fat tissue may increase inflammation that leads to more aggressive disease."
606 women with breast cancer were observed by Cristofanilli and colleagues, and classified by body mass index into three groups—normal/underweight (24.9 or below), overweight (at least 25 but less than 30), or obese (more than 30). At five years, overall survival was 56.8 percent among obese women, 56.3 percent among overweight women and 67.4 percent among normal weight women. The 10-year survival rate was 42.7 percent among obese women, 41.8 percent among overweight women and 56.5 percent among normal weight women. Researchers found that the rate of inflammatory breast cancer was 45% among obese women, compared with 30% in overweight women, and 15% in women with normal weight.
Obese or overweight women also displayed a higher risk of breast cancer recurrence. Obese women (50.8%) reported a recurrence after 5 years, compared with normal weight women (38.5%). After 10 years, the rate of recurrence was 58% in obese women and 45.4% in women with normal weight.
"Obesity goes far beyond just how a person looks or any physical strain from carrying around extra weight. Particular attention should be paid to our overweight patients," Cristofanilli said.
Drugs commonly used to treat cancer patients, such as tamoxifen, said Dr. Cristofanilli tend to increase weight gain during treatment – an effect physicians should note carefully. "We have actually become quite good at managing acute side effects such as nausea in our chemotherapy patients and it goes away within a couple of days," Cristofanilli said. "Following the nausea, our patients tend to overeat, which further increases their risk of weight gain. We need to implement lifestyle modifications interventions and develop better methods to follow these patients closely."
Clinical Cancer Research, March 15, 2008