SAN FRANCISCO—Diabetes mellitus is independently associated with decreased overall survival among patients with renal cell carcinoma (RCC) and decreased cancer-specific survival among patients with clear cell RCC, researchers reported at the 2014 Genitourinary Cancers Symposium.

Sarah P. Psutka, MD, and colleagues at Mayo Clinic in Rochester, Minn., reviewed 2,589 patients treated with nephrectomy for sporadic, unilateral RCC from 1990 to 2008 and identified 313 who had diabetes mellitus. Each of these patients was matched to two non-diabetic patients according to date of surgery, age, obesity, smoking status, histologic subtype, and other characteristics.

The patients with diabetes were significantly older non-diabetics at RCC diagnosis, more likely to be obese, and had higher Charlson scores. They also were significantly more likely to have clear cell RCC (83% vs. 76%) and to undergo nephron-sparing surgery (42% vs. 35%).

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Of the 939 matched cases and controls, 463 died within a median of 5.5 years after nephrectomy, Dr. Psutka’s group found. Survivors had a median follow-up of 8.6 years. The five-year cancer-specific survival rates did not differ significantly among diabetics and non-diabetics (84% vs. 87%), but five-year overall survival was significantly lower among the diabetic patients (66% vs. 75%).

Even after adjusting for Charlson score, diabetic patients had a significant 33% increased risk of all-cause mortality. In a subanalysis of patients with clear cell RCC, diabetic had a significant 44% increased risk of cancer-related death than non-diabetics after adjusting for potential confounders.

The symposium is co-sponsored by the American Society of Clinical Oncology, the American Society for Radiation Oncology, and the Society of Urologic Oncology.