Metachronous renal tumours after surgical management of oncocytoma

Study Type – Therapy (case series) Level of Evidence 4 What’s known on the subject? and What does the study add? Oncocytoma is a benign renal tumour that cannot be differentiated from renal cell carcinoma radiographically. Follow‐up after surgery for oncocytoma is highly variable and the natural history of surgically treated renal oncocytoma is poorly defined. We sought to assess the risk of metachronous renal tumours in a cohort of patients treated surgically for renal oncocytoma. We report a large cohort of oncocytoma patients following surgical management. This study defines the risk of metachronous renal tumours after surgical treatment of renal oncocytoma. Our findings suggest that patients with metachronous renal tumours after treatment of renal oncocytoma may have a smaller risk of renal cell carcinoma compared with patients presenting with a primary renal mass. Our findings did not support concern for increased risk of renal cell carcinoma following surgical treatment of primary renal 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.