Study Finds Obesity Raises Risk of Death After Breast Cancer Diagnosis

Breast Cancer News
November 24, 2014
Erin Rowley, Writer and Content Coordinator
Reviewed By: 
Debra DeMille, MS, RD, CSO

Researchers say if a woman is obese before, shortly after or more than a year after being diagnosed with breast cancer, her risk of dying from cancer or from any cause is higher than that of a woman with breast cancer who is a healthy weight.

Background and Goals

Obesity, having a higher-than-ideal amount of body fat, is measured using BMI, or body mass index. A BMI of more than 30 is considered obese. Studies show obesity is a risk factor for breast cancer in postmenopausal women. It’s also been linked to greater chance of recurrence, or return, of cancer and shorter lifespan in premenopausal and postmenopausal women with breast cancer.

These researchers set out to learn more about that link by looking at obesity information from a large number of studies.


Information about breast cancer-related BMI and rate of death from 82 studies was analyzed for this research. The studies featured 213,075 women with breast cancer and 41,477 deaths, 23,182 of which were from breast cancer.


The chances of an obese woman dying from breast cancer, compared to a woman of a healthy weight who also had breast cancer, were

  • 41 percent higher if she was obese before diagnosis
  • 23 percent higher if she was obese during the first year after diagnosis
  • 21 percent higher if she was obese a year or more after diagnosis

The chances of an obese woman with breast cancer dying from any cause, compared to a woman of a healthy weight who also had breast cancer, were

  • 35 percent higher if she was obese before diagnosis
  • 25 percent higher if she was obese during the first year after diagnosis
  • 68 percent higher if she was obese a year or more after diagnosis

These risks were similar in premenopausal and postmenopausal women which means age was not a factor. Hormone status, whether cancer grows because of the hormones estrogen or progesterone, did not make a significant difference.

What This Means for You

Obesity is a common problem. You probably heard about the risks of obesity before you were diagnosed. Now it’s even more important for you to maintain a healthy weight. It could lower your chance of dying from breast cancer and from other causes.

A healthy diet and frequent exercise are essential to weight loss. But it can be hard to focus on those things while you’re going through treatment. Side effects like stress, fatigue or depression may stop you from eating healthy and working out. Talk to members of your healthcare team, such as your oncologist and a registered dietician, someone who has special training in the use of diet and nutrition to keep the body healthy, about any side effects and about how to make your lifestyle as healthy as possible while going through treatment. For more information about how to work diet and exercise into your routine during breast cancer treatment, read our Guide to Understanding Complementary Therapies.

Another way being overweight could affect your breast cancer experience is that you may need a higher dose of medicines like chemotherapy than people who are thinner. Talk to your doctor to make sure your treatment plan takes your weight into account.

Researchers suggest futures studies look at how other health issues affect survival in obese women with breast cancer. They also suggest looking into how weight loss, whether planned or accidental, affects survival and what programs are best for helping women with breast cancer lose weight and live longer. If you’re interested in participating in future trials about breast cancer and obesity, visit and talk to your doctor.

Chan, D. S. M.; Vieira, A. R.; Aune, D. Body mass index and survival in women with breast cancer—systematic literature review and meta-analysis of 82 follow-up studiesAnnals of Oncology. June 18, 2014; doi:10.1093/annonc/mdu042.

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