Clinical Management of Synchronous and Metachronous Renal Lesions in Patients With Oncocytoma Treated With Nephrectomy: A 30-Year Single-Center Experience.

BACKGROUND

The natural history of renal oncocytoma (RO) following surgical resection remains unclear. We examined a cohort of post-nephrectomy patients with RO, focusing on the management of synchronous and metachronous tumors and their clinical course under surveillance.

METHODS

This retrospective, single-institution study analyzed patients from 1990 to 2020 with at least 24 months of follow-up. Patient characteristics and management of synchronous and metachronous tumors were recorded. Cox regression identified risk factors for metachronous tumors, while Kaplan-Meier and log-rank tests assessed metachronous-free survival (MFS).

RESULTS

Among 328 patients (median follow-up: 109 months), 19% (n = 63) had synchronous renal tumors on preoperative imaging. Of these, 27 underwent additional procedures, revealing renal cell carcinoma (RCC)/cortical neoplasm (n = 7), benign lesions (n = 5), or secondary RO (n = 13). Two specimens were unavailable. Metachronous renal lesions developed in 8.5% (n = 28), with 18 undergoing active surveillance. Among 8 patients undergoing biopsy or surgery, 3 had RCC/cortical neoplasm, 4 had RO, and 1 specimen was inconclusive. 5-year MFS were 98.8% in patients with a single lesion at diagnosis and 88% for patients with presence of synchronous renal lesions (P = .004). Higher BMI (HR 1.09, CI 1.01-1.17, P = .026) and synchronous lesions at diagnosis (HR 2.67, CI 1.16-6.14, P = .021) were significant risk factors for metachronous tumors.

CONCLUSION

Patients with RO have a very low risk of harboring RCC in synchronous or metachronous lesions, supporting active surveillance as a safe strategy. However, those with synchronous kidney tumors at diagnosis face an increased risk of metachronous disease and may require closer monitoring.