Metachronous renal tumours after surgical management of oncocytoma.

OBJECTIVE

• To assess the risk of metachronous renal cell carcinoma (RCC) and benign renal tumours after surgical treatment of primary renal oncocytoma.

PATIENTS AND METHODS

• Patients treated for primary renal oncocytoma between 1970 and 2007 were identified. Tumours were reviewed by a urological pathologist and patients were followed for subsequent renal tumours.

RESULTS

• Of 424 patients with a median follow up of 7.1 year, 17 (4.0%) patients were diagnosed with a metachronous renal tumour at a median of 3.0 years (range 0.3-16 years). Of the 17 metachronous tumours, eight were oncocytoma, four were RCC and five were not resected or biopsied. • Eleven metachronous tumours occurred after solitary unilateral oncocytoma, five occurred after multifocal unilateral oncocytoma, and one occurred after multifocal bilateral oncocytoma. • Estimated 10-year tumour-free and RCC tumour-free survival was 94.8% and 98.7%, respectively. Patients with primary multifocal oncocytoma were at higher risk of metachronous tumour (hazard ratio 4.0; P = 0.007). Initial oncocytoma size (hazard ratio 1.1; P = 0.11) was not highly associated with risk of tumour recurrence.

CONCLUSIONS

• To our knowledge, we report the largest cohort of oncocytoma after surgical management. Metachronous renal neoplasm in a patient with previous oncocytoma is more likely to be benign compared with patients who present with a renal tumour for the first time. Multifocal primary oncocytoma is associated with metachronous renal tumours. • Overall, the risk of metachronous RCC in a patient with an oncocytoma is similar to that of the general population, which does not support the use of routine cross-sectioning imaging surveillance.