Obesity Linked with Higher Risk of Death for Premenopausal Women with ER-Positive Breast Cancer

ASCO Annual Meeting
May 14, 2014

A recent data analysis showed that obesity increases the risk of death from estrogen receptor (ER)-positive breast cancer for women who have not been through menopause. Menopause usually begins in a woman’s mid-40s or early to mid-50s when her ovaries stop releasing eggs and her body makes less of the hormones estrogen and progesterone. Woman who are premenopausal have not been through menopause. Those who are postmenopausal have been through menopause. Estrogen receptor-positive breast cancer is a type of breast cancer that depends on estrogen to grow and spread.

As part of this study, researchers analyzed information from 80,000 women who participated in 70 different clinical trials, comparing information from women who received the same treatment in the same clinical trial. They used body mass index (BMI) to define normal weight, overweight, and obesity. BMI is the ratio of a person’s weight and height. For this study, a normal BMI was considered to be between 20 and 25, an overweight BMI was between 25 and 30, and a BMI of 30 or higher was considered as obesity.

Among the premenopausal women with ER-positive breast cancer, researchers found that deaths from cancer were one-third higher for women who were obese than for those who were normal weight. However, obesity was not linked to an increased risk of death from cancer for postmenopausal women with ER-positive cancer or for women with ER-negative disease.

What this means for patients

“Obesity substantially increases blood estrogen levels only in postmenopausal women, so we were somewhat surprised to find that obesity affected the chance of recovery and survival only in premenopausal women,” said Hongchao Pan, PhD, a researcher at the University of Oxford in the United Kingdom. “This means we don’t understand the main way obesity affects recovery.”

Questions to Ask Your Doctor

  • What type of breast cancer do I have? What does this mean?
  • What is my BMI? What does this mean?
  • Would I benefit from losing weight? How is that determined?
  • Who can help me set up a safe exercise and/or weight loss program?

More Information

Guide to Breast Cancer

Managing Your Weight After a Cancer Diagnosis

How to Make Positive Lifestyle Changes While Living With Cancer