Women with high BMI are at increased risk of dying from breast cancer

Breast cancer patients with a high body mass index (BMI) have a poorer cancer prognosis later in life. Specifically, their treatment effect does not last as long and their risk of death increases.

"Overall, women should make an effort to keep their BMI less than 25," said Marianne Ewertz, M.D., professor in the Department of Oncology at Odense University Hospital, Denmark. "Those who have a high BMI should be encouraged to participate in mammography screening programs for prevention efforts."

Ewertz and colleagues examined the influence of obesity on the risk of breast cancer recurrence and mortality in relation to adjuvant treatment. She presented study results at the CTRC-AACR Annual San Antonio Breast Cancer Symposium, held Dec. 9-13.

Using the Danish Breast Cancer Cooperative Group database, they evaluated health information — such as status at diagnosis, tumor size, malignancy grade, number of lymph nodes removed, estrogen receptor status, treatment regimen, etc. — from almost 54,000 women. Ewertz and colleagues were able to calculate BMI for 35 percent of the women, whose information about height and weight was available. A healthy, normal BMI score is between 20 and 25; a score below the normal range indicates underweight and a score above indicates overweight.

After 30 years of follow-up (from 1977 through 2006), the researchers found that women with higher BMIs were older and had more advanced disease at diagnosis compared with those who had a BMI within the normal range. The risk of distant metastases increased the higher the BMI. However, BMI played no role in loco-regional recurrence.

Women with a high BMI had an increased risk of dying from breast cancer, a finding that remained constant over the study period. Further, adjuvant treatment seemed to lose its effect more rapidly in obese patients, according to Ewertz.

"More research is needed into the mechanisms behind the poorer response to adjuvant treatment among obese women with breast cancer," she said.