Prognostic relevance of capsular involvement and collecting system invasion in stage I and II renal cell carcinoma

OBJECTIVE To define the prognostic relevance of capsular involvement (invasion with no penetration) and collecting-system invasion in patients with stage I (pT1N0M0) and stage II (pT2N0M0) renal cell carcinoma (RCC), by evaluating the outcome of patients treated with nephrectomy. PATIENTS AND METHODS In all, 519 patients from a kidney cancer database treated with nephrectomy for stage I and II RCC between 1985 and 2005 were assessed retrospectively. The primary endpoint was recurrence-free survival time. The prognostic relevance of capsular involvement and collecting-system invasion were examined using univariate and multivariate survival analysis. RESULTS Capsular involvement and collecting-system invasion were evident in 112 (21.6%) and 39 (7.5%) patients, respectively. Capsular involvement was associated with higher Fuhrman grades and larger tumours. The incidence of collecting-system invasion was higher in patients with microvascular invasion. The median follow-up was 49 months. In univariate analysis, patients with capsular involvement and collecting-system invasion had a worse prognosis than patients without (P = 0.007 and < 0.001, respectively). In multivariate analysis, capsular involvement (hazard ratio 1.84, P = 0.036) and collecting-system invasion (3.78, P < 0.001) were independent prognostic factors of recurrence-free survival. Interestingly, there was no survival difference between patients with capsular involvement in stage I/II and patients with invasion of perinephric tissue (pT3aN0M0). CONCLUSIONS These findings suggest that capsular involvement and collecting-system invasion are poor prognostic findings in stage I and II RCC. They should both be considered when planning the follow-up. A revised pT3a stage including patients with capsular involvement could improve its prognostic validity.