Active surveillance for larger (cT1bN0M0 and cT2N0M0) renal cortical neoplasms.

Objectives: To report our experience with patients undergoing active surveillance (AS) with Stage T1bN0M0 and T2N0M0 tumors. AS is a reasonable option for selected patients with renal cortical neoplasms (RCNs). Most patients undergoing AS are high-risk surgical candidates with Stage T1a lesions. The natural history of larger (Stage cT1bN0M0 and cT2N0M0) RCNs remains undefined.

Methods: Our institution's institutional review board-approved urologic oncology database was reviewed and identified 229 patients undergoing AS for RCNs. Of this cohort, 36 patients with 42 RCNs ≥4 cm were monitored at regular intervals with imaging. Patients with metastatic disease were excluded. The patient demographics, presentation, comorbidity level (Charlson comorbidity index), tumor size, tumor growth rate, and survival data were recorded. A failure of AS was defined as a progression to metastasis or a change from AS to a delayed surgical intervention.

Results: The mean Charlson comorbidity index was 2.83, with 52.8% of patients having an index of ≥3, indicating a high surgical risk. The mean tumor size on the initial computed tomography scan was 7.13 cm (range 4-13.7), and the mean growth rate was 0.57 cm/y (range 0-5.9). With a mean follow-up of 36 months (range 6-96), 5 patients (13.8%) had failure. Three lesions were treated with laparoscopic radical nephrectomy and found to be pT2N0M0 on final pathologic examination. Two patients (5.6%) in this cohort developed metastatic disease, and no cancer-specific deaths occurred.

Conclusions: Patients with Stage T1bN0M0 and T2N0M0 RCNs, monitored for a mean follow-up of 3 years, demonstrated a growth rate of 0.57 cm/y, with only 5.6% of patients progressing to metastatic disease.