Black women with breast cancer typically have a worse prognosis than white women, and the results of a new study suggest that insulin resistance may be a factor in the disparity. Findings from the study were reported in Breast Cancer Research.

In a cross-sectional, multicenter study, researchers looked at data from 515 women with breast cancer (83% white and 17% black) to evaluate whether insulin resistance contributed to the effect of race on breast cancer prognosis.

After looking at factors related to insulin resistance, metabolic syndrome, and obesity, overall, they found that insulin resistance and poor breast cancer prognosis were both higher in black women than in white women (40% versus 20% and 28% versus 15%, respectively). They also found that tumors in black women had higher insulin receptor expression, which is what insulin binds to in the tumors, and were associated with a worse prognosis.

“Our results raise a number of questions for future research and patient care. It will be important in future studies to explore whether lowering insulin levels or targeting insulin receptor signaling will improve breast cancer disparities,” the authors said. “This is certainly just one of a number of complex factors that contribute to racial disparities in breast cancer prognosis.”