Tumor necrosis is a strong predictor for recurrence in patients with pathological T1a renal cell carcinoma

Patients with pT1aN0M0 renal cell carcinoma (RCC) generally have good prognosis, and recurrence is rare. However, metastasis develops postoperatively in a small number of patients with pT1aN0M0 RCC. The present study was undertaken to identify predictors for recurrence in patients with pT1aN0M0 RCC. We reviewed the clinicopathological factors of 133 patients with pT1aN0M0 RCC who underwent radical or partial nephrectomy at the Department of Urology, National Defense Medical College (Saitama, Japan). Clinicopathological factors, including age, gender, tumor size, histological subtype, tumor grade, microvascular invasion, histological tumor necrosis, C-reactive protein levels and performance status were reviewed. These factors were compared between patients with and without postoperative recurrence. Recurrence-free survival (RFS) and cause-specific survival (CSS) rates were calculated using the Kaplan-Meier method. Univariate and multivariate analyses were performed to determine independent factors predicting recurrence in patients with pT1aN0M0 RCC. The 5-year RFS and CSS rates were 97.2 and 99.1%, respectively. When clinicopathological factors were compared between patients with and without recurrence, tumor size (P=0.0390) and percentage of tumor necrosis (P<0.0001) were significantly different between groups. All patients with recurrence had primary lesions ≥3 cm. By univariate analysis, tumor size (P=0.0379) and the presence of tumor necrosis (P=0.0319) were significant predictors for recurrence; tumor necrosis was also an independent predictor for recurrence (P=0.0143). In patients with pT1b tumors ≤5 cm (recurrence rate, 16.8%; n=48), the percentage of tumor necrosis was significantly higher in patients with recurrence compared with those without (P=0.0261). This suggests that tumor necrosis may be an important predictor for recurrence in small RCCs. Although recurrence is rare in pT1a RCC, the presence of tumor necrosis may be an important predictor for recurrence. Particularly, patients presenting with pT1a RCC with histological tumor necrosis should undergo careful follow-up.