How Women can Trim Breast Cancer Risks

Breast cancer risks linked with diabetes and obesity

/ Author:  / Reviewed by: Joseph V. Madia, MD

(RxWiki News) You've probably heard that obesity is a risk factor for breast cancer. Now researchers are finding diabetes is another. And there are other things that both increase and decrease a woman's risk of getting breast cancer.

After the age of 60, being obese or having diabetes significantly increases a woman's breast cancer risks, according to a recent Swedish study. 

"Maintaining a healthy weight is one of the best things you can do."

Low blood lipids also increase her risks, while high lipids seem to lower her chances. And one type of diabetes drug decreases the risks, while another increases a woman's likelihood of developing breast cancer.

To determine a comprehensive cancer risk profile, this study examined healthcare data from 1.5 million people living in Southwestern Sweden.

For the first finding that diabetes and obesity after the age of 60 increase breast cancer risks, Håkan Olsson, M.D., professor in the departments of oncology and cancer epidemiology at Lund University, and colleagues studied the records of 2,724 patients for up to a decade before they were diagnosed with breast cancer. These cases were compared with 20,542 people who never developed the disease.

Dr. Olsson's group found obesity increased a woman's risk by 55 percent.

"In this type of study, associations can be found and explored, but they are not proven," Patrick D. Maguire, M.D., a radiation oncologist in North Carolina and author of When Cancer Hits Home: An Empowered Patient is the Best Weapon Against Cancer, told dailyRx. "Nevertheless, the 55% relative increased breast cancer risk for obese women over 60 in this Swedish study is quite impressive."

Women who were living with diabetes up to four years had a 37 percent greater chance of developing breast cancer.

Dr. Maguire said, "While there may be a direct link between the two disease processes, a more basic explanation may be that the risk factors for both diseases (like obesity, relative inactivity, etc.) overlap significantly. The beauty there is that women may likely be able to decrease their risk of both diseases by similar methods."

The study also found:

  • Women who had very low levels of blood lipids (primarily cholesterol) had a 25 percent increased risk of breast cancer
  • High blood lipid levels, on the other hand, were associated with lower risks of the disease.

Researchers found some interesting associations with diabetes medications:

  • After examining national prescription registries, researchers found that the use of diabetes medication Lantus (glargine) almost doubled the risk of developing any cancer.
  • Metformin - marketed under such brand names as Glucophage, Glumetza, Fortamet, Riomet - lowered the cancer risk by eight percent in patients who had diabetes.

Dr. Olsson says the number of people who developed breast cancer while taking these medications was too small to make risk associations. He says more research must be conducted to clarify the link between these medications and specific cancers. 

"The collective research to date strongly suggests that women who want to decrease their relative breast cancer risk should strive for a lean body, and that regular physical activity is a good way to get there," Dr. Maguire concludes.

Findings from this study were reported at the 2011 CTRC-AACR San Antonio Breast Cancer Symposium. Research is considered preliminary before it's published in a peer-reviewed journal.

Reviewed by: 
Review Date: 
December 6, 2011
Last Updated:
September 27, 2012