Multi-institutional analysis of localized renal cell carcinoma that demonstrates the impact of diabetic status on prognosis after nephrectomy

Background: The purpose of our study was to determine whether preoperative diabetes mellitus (DM) can predict the prognosis of localized clear-cell renal cell carcinoma (RCC). Methods: At five institutes, 2,597 patients with pT1 and pT2 clear-cell RCC were enrolled. Univariate and multivariable analyses were performed to determine factors that associated with recurrence-free survival (RFS), cancer-specific survival (CSS), and overall survival (OS). To identify the effect of DM on survival after recurrence, a subgroup of 127 patients who had recurrences was analyzed. Results: In total, 357 patients had DM. Compared with patients without DM, these patients were older, more likely to be male, and had a higher body mass index, lower GFR, and higher incidence of hypertension. Kaplan-Meier curves showed that patients with DM had a significantly worse rate of RFS, CSS, and OS than patients without DM (log-rank test, all P < 0.05). Multivariate analysis revealed that DM was an independent prognostic factor in terms of RFS, CSS, and OS. In the subgroup analysis of 127 patients with recurrence, DM was associated with a lower survival rate after the initial recurrence. Conclusions: DM appeared to be an important determinant of prognosis in clear-cell localized RCC, especially in patients experiencing recurrence.