Is There a Relationship Between Obesity and Breast Cancer?

As we begin a new year, we can look forward to more in-depth discussion about breast health. In this post, I am providing some information on the modifiable risk factor obesity and breast cancer. Is there a relationship between obesity and breast cancer? Research shows some evidence of a potential relationship between the two. A study looking at breast cancer survivors found that women who had lost weight and/or maintained closer to their ideal body weights actually had fewer recurrences and new primary breast cancers compared to those women who did not. Other research has described a link between obesity and postmenopausal breast cancer. The theories behind why obesity increases a woman’s risk are multiple.

Posted on | Katherine Lee, MD | Comments ()

As we begin a new year, we can look forward to more in-depth discussion about breast health. In this post, I am providing some information on the modifiable risk factor obesity and breast cancer. Is there a relationship between obesity and breast cancer? Research shows some evidence of a potential relationship between the two. A study looking at breast cancer survivors found that women who had lost weight and/or maintained closer to their ideal body weights actually had fewer recurrences and new primary breast cancers compared to those women who did not. Other research has described a link between obesity and postmenopausal breast cancer. The theories behind why obesity increases a woman’s risk are multiple.

First, adipose or fat cells (found abundantly in the breasts) produce a specific type of estrogen called estrone. Second, adipose cells secrete cytokines such as adinopectin and leptin. In obesity, leptin levels increase and adinopectin levels decrease. These changes seem to be linked to increased breast cancer risk. Third, obesity has other physiological effects on the body such as increased insulin levels and insulin like growth factor-1, both of which have been linked to breast cancer. Lowering these hormones may be beneficial, and we have evidence which supports this.

Recent data has shown that using a specific diabetes drug called metformin was more beneficial when combined with chemotherapy than receiving chemotherapy alone. Metformin may also decrease one’s risk of developing breast cancer. The exact mechanisms of obesity and breast cancer risk are not known, and there may be other mechanisms at work here. More studies are needed to answer these questions.

What I currently recommend to my patients is to try and eat a well-balanced diet but higher in vegetables and fruit quantities, avoid empty calories like junk food, and try to maintain a healthy weight. To do this after menopause usually requires exercise. Controlling your weight also helps to reduce risk for other cancers such as colon cancer and decreases your risk for chronic conditions such as diabetes and heart disease.

Being overweight does not mean you will acquire these problems, but I think it is important to remember that cancers usually develop because of genetic susceptibility and the exposure to environmental risk factors. In other words, you can’t change your genes but you can change your environment. All of us can change our environment (food intake, exercise) even if it is one small step at a time. As we begin the New Year, we can look for ways to achieve good breast health, which can also lead to total body health.

Blog written by Katherine Lee, MD
Dr. Lee has been at the Cleveland Clinic Breast Cancer Center for 12 years and her interests include breast cancer risk...