Potential Link Between Insulin Resistance and Racial Disparities in Breast Cancer Prognosis
Posted: Friday, August 14, 2020
According to a study published in Breast Cancer Research, insulin resistance may play a role in the relation between race and poor prognoses in breast cancer. Nina A. Bickell, MD, PhD, of the Icahn School of Medicine at Mount Sinai, New York, and colleagues believe their findings could have clinical implications such as adjusting insulin dosing.
“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,” said Dr. Bickell in a Mount Sinai press release.
In this multicenter study, which included 10 hospitals, a total of 515 women were recruited. The women were newly diagnosed with invasive breast cancer and self-identified as Black (17%) and White (83%). Insulin resistance was measured using homeostatic model assessment of insulin resistance (HOMA-IR), and its association with prognosis was calculated using the multivariate linear mediation model. Breast cancer tissue samples were examined for insulin resistance and insulin-like growth factor receptor expression by immunohistochemistry.
The investigators reported that insulin resistance expression seemed to be higher in tumors from Black women than in those from White women (79% vs. 52%, P = .004). A poor cancer prognosis was also more prevalent in Black women than in White women (28% vs. 15%. P = .004). “Insulin resistance mediated in part the link between race and breast cancer prognosis (determined by Nottingham Prognostic Index),” they reported. The mediation model showed that HOMA-IR formed a connecting link between race and poor prognosis.
“These findings may indicate that Black women are not only more likely to have hyperinsulinemia, but are also more susceptible to the tumor promoting effects of elevated insulin by direct effects of insulin on tumor insulin receptor signaling,” Dr. Bickell and colleagues commented.
Disclosure: The study authors reported no conflicts of interest.
