Diabetes Mellitus as an Independent Predictor of Survival of Patients Surgically Treated for Renal Cell Carcinoma: A Propensity Score Matching Study.

PURPOSE: Controversy continues about the prognostic significance of diabetes mellitus in patients with renal cell carcinoma. We investigated the relationship between diabetes mellitus and prognosis in patients with renal cell carcinoma who underwent surgical treatment.
MATERIALS AND METHODS: We reviewed data on 3,075 consecutive patients treated with radical or partial nephrectomy for nonmetastatic renal cell carcinoma from 1988 to 2013. The propensity score of a diabetes mellitus history was calculated and 417 patients with diabetes were matched to 814 without diabetes in a 1:2 ratio. The potential association of preexisting diabetes and preoperative HbA1c with outcomes was tested. Univariate and multivariate analyses were performed to identify independent predictors of progression-free, cancer specific and overall survival.
RESULTS: Before matching, patients with diabetes showed worse prognosis in terms of progression-free, overall and cancer specific survival (each p<0.001). In matched cohorts 1,231 patients with diabetes showed progression-free (p=0.001), cancer specific (p<0.001) and overall survival (p<0.001) inferior to that in patients without diabetes. On multivariate analyses diabetes was an independent predictor of disease progression (HR 1.766 p=0.002), all cause mortality (OR 1.825, p=0.001) and cancer specific mortality (HR 2.266, p=0.001). Among patients with diabetes who had available preoperative HbA1c data high HbA1c independently predicted postoperative disease progression (HR 2.221, p=0.023).
CONCLUSIONS: Diabetes mellitus is an independent predictor of cancer specific and overall survival in patients who undergo surgery for renal cell carcinoma. Also, in patients with diabetes mellitus poor glycemic control is associated with a higher risk of progression.