Diabetes mellitus (DM) is independently associated with decreased overall and cancer-specific survival in patients who undergo surgery for clear-cell renal cell carcinoma (ccRCC), according to a new study.

A team at Mayo Clinic in Rochester, Minn., led by R. Houston Thompson, MD, reviewed data from 1,964 patients who had surgery for sporadic, unilateral ccRCC from 1990 to 2008. Of these, 257 (13%) had DM. The researchers matched these patients 1:2 to referent patients without diabetes according to clinicopathological and surgical features. The median postoperative follow-up was 8.7 years.

On multivariable analysis, DM was independently associated with a significant 55% increased risk of cancer-specific mortality and a significant 32% increased risk of all-cause mortality, the researchers reported in The Journal of Urology (2014;192:1620-1627).

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“These findings underscore the importance of considering the effect of DM among other comorbidities on outcomes during risk stratification in RCC,” the authors concluded. “They also support the hypothesis regarding the potential influence of the hyperglycemic and hyperinsulinemic DM states on ccRCC behavior and as such they warrant further investigation.”

The researchers explained that “high plasma insulin results in increased hepatic production of IGF-1, which has a central driving role in cell proliferation and differentiation, protecting against apoptosis.”

Dr. Thompson’s group noted that the strengths of their study include a substantial follow-up, but the study had some limitations, including the retrospective design, which precluded the ability to definitively test a causal relationship between DM and decreased overall survival.