Study Links Diabetes and Worse Outcomes in Long-Term Survivors of Metastatic Breast Cancer

Newswise — Women who are longer-term survivors of metastatic breast cancer may have a worse survival rate if they have diabetes and poorly controlled blood sugar levels, according to a new study presented Sunday, June 12 at ENDO 2022, the Endocrine Society’s annual meeting in Atlanta, Ga.

This is the first study to specifically examine the effect of blood sugar control on cancer outcomes in patients with advanced breast cancer, according to lead researcher Y.M. Melody Cheung, M.D., of Brigham and Women’s Hospital, Harvard Medical School in Boston, Mass.

To date, there has been little research conducted on the effects of diabetes, and in particular, the impact of poor blood sugar control on advanced breast cancer outcomes. Existing studies have primarily focused on patients with early rather than advanced cancer.

Researchers studied 488 patients with metastatic breast cancer. Half had diabetes. The study found that overall survival at five years was similar between the two groups. However, amongst those that survived at least 8 years after their cancer diagnosis, survival for those without diabetes was better than those with diabetes (87% vs. 67% at 10 years). In these longer-term survivors, survival was also better among those with good blood sugar control compared with those with poor blood sugar control (83% vs. 63% at 10 years).

“Our findings suggest that in patients with breast cancer who have a relatively good prognosis despite their cancer diagnosis, a more proactive management of blood sugar may lead to a longer lifespan,” Cheung said.

“These findings are important as they suggest that diabetes treatment and blood sugar goals should be tailored specifically to patients even with advanced cancer based on their projected prognosis,” she added.

“It remains uncertain whether control of blood sugars in patients with diabetes and breast cancer can improve the outcomes of the cancer itself,” Cheung said. “In some instances, blood sugar control may not be strongly pursued by doctors, especially in cases where the cancer is advanced, and strict diabetic control may be considered overly burdensome for patients. A link between poor blood sugar control and worse cancer outcomes may modify the way doctors treat diabetes in patients with advanced breast cancer.”

Cheung will present the findings during a diabetes news conference on Sunday, June 12 at 10 AM EST. 

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