Ovarian cancer patients with type 2 diabetes have a greater chance of dying from their cancer — or from any cause — than patients without diabetes, according to a meta-analysis of 12 studies.
The research, “Diabetes mellitus and long-term mortality of ovarian cancer patients. A systematic review and meta-analysis of 12 cohort studies,” was published in Diabetes/Metabolism Research and Reviews.
Diabetes, a chronic disease that affects nearly 9 percent of adults worldwide, is characterized by the pancreas’ inability to produce enough insulin or to use it effectively. By affecting blood-sugar levels, diabetes can affect the prognosis of other diseases. Some studies suggest it reduces cancer survival rates.
To assess whether diabetes influences the mortality rates of ovarian cancer patients, researchers at the Gillings School of Global Public Health at the University of North Carolina at Chapel Hill did a meta-analysis of studies dealing with overall survival, cancer-specific mortality, and mortality from all causes in patients with ovarian cancer and diabetes. The studies, conducted between 1961 and 2012, covered 17,451 ovarian cancer cases.
Four studies looked at the median survival times of those with various stages of diabetes. Patients without diabetes survived longer than those with the disease.
Ovarian cancer patients with diabetes had a 44 percent higher risk of dying from any cause than those without diabetes. Similarly, they had a 44 percent higher risk of dying from their cancer, although there was a wide statistical range from study to study.
The team proposed several explanations for the increased mortality among ovarian cancer patients with diabetes. For example, insulin deficiency triggers the expression of proteins, like interleukin-6, that promote tumors. In addition, long-term insulin use can activate insulin-derived signaling pathways that promote tumor proliferation and progression.
The studies did not discriminate between type 1 and type 2 diabetes, but because type 2 diabetes accounts for 90 percent of diabetes in adults, the researchers said their findings can be generalized to type 2 diabetes.
“In conclusion, our study suggests that diabetes, particularly type 2 diabetes, is associated with a 40% to 50% relative increase in the risk of long-term all-cause and long-term cancer-specific mortality among ovarian cancer patients,” they wrote. “Future studies should investigate if type 1 diabetes has the same effect to mortality among ovarian cancer patients.”