Women who are overweight or obese when they are diagnosed with breast cancer have a higher risk of cancer recurrence or related death when compared with leaner women, according to a study presented at the European Breast Cancer Conference.
Researchers studied data from 1,909 patients enrolled in a study between 1997 and 1999. The study was designed to investigate different dosing schedules for adjuvant chemotherapy in patients where cancer cells were found in the lymph nodes, because the presence of cancerous cells in lymph nodes signifies a higher chance of the cancer recurring.
After extracting height and weight data from the patient records, the researchers evaluated the relationship between BMI and relapse-free survival (RFS) and overall survival (OS). Slightly more than 1% of the patients were underweight, 32.6% normal weight, 32.9% overweight and 33.3% obese.
The researchers found that BMI affected both RFS and OS. The 10-year RFS of an overweight patient was 70%, but for obese patients, it was only 65%.
“When you consider that data from 2007-8 show that 68% of US adults aged 20 years and over were overweight or obese, as compared to only 56% of the same group in 1998-1994, you can see the way the problem is growing. That is why we think it is a matter of urgency to find out as much about the relationship between obesity and cancer as we can,” Jennifer Ligibel, MD, an oncologist at the Dana-Farber Cancer Institute and associate professor at Harvard Medical School, stated in a press release.
The researchers warned that the relationship between weight and breast cancer recurrence remains unclear, and they intend to follow up with further studies about how weight-related factors influence breast cancer outcomes.
“Obesity is a modifiable factor, and although there is not yet enough evidence to say with certainty that losing weight or exercising more regularly will decrease the risk of breast cancer recurrence, there are consistent links between lifestyle factors such as diet, weight and physical activity patterns and breast cancer prognosis,” Ligibel added. “If future studies show that making changes in lifestyle behaviors for women with early breast cancer will improve survival rates, then lifestyle interventions may one day become a standard part of breast cancer care.”