Re-evaluation of the tumour-node-metastasis staging of locally advanced renal cortical tumours: Absolute size (T2) is more significant than renal capsular invasion (T3a)

OBJECTIVE: To determine which factor was more predictive of adverse outcome in our institutional experience with T2N0M0 and T3N0M0 renal cortical tumours (RCTs) treated surgically, as the current Tumour-Node-Metastasis (TNM) staging system for RCTs differentiates between tumours of >7.0 cm but confined to the renal capsule (T2) and tumours that extend through the renal capsule regardless of size (T3a). MATERIALS AND METHODS: We analysed our institutional database of surgical urological oncology for all patients with T2N0M0 and T3aN0M0 RCT treated with partial or radical nephrectomy from 1988 to 2002. All patients with preoperative metastasis, bilateral or multifocal tumours, nonsporadic disease or benign histology were excluded from analysis. A follow-up of ≥6 months from the time of surgery was required for inclusion. Primary outcomes included local and distant recurrence, and death. RESULTS: In all, 717 patients had a partial or radical nephrectomy for RCT during the study period. After exclusion criteria were applied, 21 patients with T2N0M0 and 97 with T3aN0M0 tumours were eligible; the median (mean, range) age was 63 (16.6-88.3) years and follow-up 30.5 (40.8, 6-162) months. The estimated 5-year disease-free survival was 68% and 85% for T2N0M0 and T3aN0M0 RCT, respectively (P = 0.002). The 5-year disease-specific survival was 81% and 94% for the T2N0M0 and T3aN0M0 groups, respectively (P = 0.085). CONCLUSION: Patients with T3aN0M0 tumours appear to have better disease-free and disease-specific survival than those with T2N0M0 disease, which suggests that tumour invasion through the renal capsule is not as significant as the absolute tumour size.