Diabetes May Predispose Women to More Advanced Breast Cancer

Lorraine Lipscombe, MD, MSc, FRCPC

The link between diabetes and late-stage breast cancer is strong, according to a new study.

The study, published in Breast Cancer Research and Treatment, found that breast cancer patients with diabetes were significantly more likely to be diagnosed with advanced-stage breast cancer than those without diabetes.

“Our findings suggest that women with diabetes may be predisposed to more advanced-stage breast cancer, which may be a contributor to their higher cancer mortality,” Lorraine Lipscombe, MD, MSc, FRCPC, a scientist at the Institute for Clinical Evaluative Sciences and Women’s College Research Institute in Toronto said in a statement.

Although women with diabetes have higher breast cancer incidence and mortality, the link between diabetes and breast cancer stage at diagnosis has not been examined.

The study examined the stage at diagnosis among more than 38,000 Canadian women aged 20-105 years who were newly diagnosed with invasive breast cancer between 2007 and 2012. Of those women, 15.9% had diabetes.

The study found that women with diabetes were 14% more likely to be diagnosed with stage II breast cancer, 21% more likely to have stage III disease, and 16% more likely to have stage IV breast cancer, than to present with stage I.

Researchers also found that women with diabetes had a higher risk of lymph node metastases and tumors larger than 2 centimeters.

“In addition, the risk of advanced-stage breast cancer was greatest in younger women and those with longer standing diabetes,” Lipscombe said.

The later stage diagnosis translated into a 15% decrease in 5-year survival for diabetes patients at the time of cancer diagnosis.

According to researchers, diabetes was associated with more advanced-stage breast cancer even after accounting for differences in screening mammogram use and other factors.

Therefore, the results show that diabetes may predispose individuals to more aggressive breast cancer, which may be a contributor to their higher cancer mortality.

Lipscombe LL, Fischer HD, Austin PC, et al. The association between diabetes and breast cancer stage at diagnosis: a population-based study. Breast Cancer Res Treat. 2015;150(3):613-620.