Extra pounds are linked to a higher risk of recurrence of the most common type of breast cancer even with ideal treatment, according to a study.
Obesity at diagnosis of breast cancer is associated with about a 30% higher risk of recurrence and a nearly 50% higher risk of death despite optimal treatment, Joseph Sparano, MD, of the Albert Einstein College of Medicines Montefiore Medical center in Bronx, N.Y., said in a news release.
The findings suggest extra body fat causes hormonal changes and inflammation that may drive some cases of breast cancer to spread and recur despite treatment, according to the researchers, whose study appeared Aug. 27 on the website of the journal Cancer.
Previous research found women who are obese when diagnosed with breast cancer have an increased risk of dying prematurely compared with women of normal weight. In the new study, researchers compared the health outcomes of obese and overweight patients with others in a large group of women with stage I-III breast cancer who had participated in three National Cancer Institute-sponsored treatment trials led by the Eastern Cooperative Oncology Group.
All trials required participants to have normal heart, kidney, liver and bone marrow function, thereby excluding patients with other significant health issues.
The researchers found that increasing body mass index significantly increased womens risk of cancer recurrence and death, despite optimal treatment including chemotherapy and hormonal therapy but only in women with hormone receptor-positive breast cancer, which accounts for approximately two-thirds of all breast cancer cases in the United States and worldwide. In those women, there was a stepwise relationship between increasing body mass index and poor outcomes,
Treatment strategies aimed at interfering with hormonal changes and inflammation caused by obesity may help reduce the risk of recurrence, Sparano said.
The study abstract is available at http://onlinelibrary.wiley.com/doi/10.1002/cncr.27527/abstract.