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306 The natural evolution of oncocytomas: Can they be safely followed by surveillance?
Title
306
The natural evolution of oncocytomas: Can they be safely followed by surveillance? Eur Urol Suppl 2015;14/2;e306
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Richard P.O. 1 , Jewett M.A.S. 1 , Bhatt J.R. 1 , Timilshina N.1 , Evans A.J.2 , Finelli A. 1 1 Princess
Margaret Cancer Centre, University Health Network and The University of Toronto, Dept. of Surgery and Surgical Oncology,
Division of Urology, Toronto, Canada, 2 Toronto General Hospital, University Health Network and The University of Toronto, Dept. of Laboratory Medicine and Pathobiology, Toronto, Canada INTRODUCTION & OBJECTIVES: Despite the recognition that a large proportion of small renal masses are benign, the vast majority are still being managed by upfront ablative approaches. Many centers have demonstrated that percutaneous renal tumour biopsies (RTBs) is a safe and accurate alternative approach to preoperatively identify the histology of renal cell tumours, including oncocytomas. However, noninvasive methods to reliably differentiate oncocytomas from their malignant counterparts are still lacking. Moreover, little studies on the natural history on oncocytomas have been published. The objectives of this study was to evaluate the growth rate of histologically proven oncocytoma and to improve our understanding of the natural history of these benign lesions. MATERIAL & METHODS: This is single-center retrospective study in which we identified 110 patients diagnosed with an oncocytoma following renal tumour biopsy (RTB) or surgery between 2003 and 2014. Masses with less than 12 months of imaging follow-up were excluded, leaving 80 (72 patients) available for analysis. The average growth rate was estimated using mixed effect linear model adjusted for individual clustering and using a random intercept and a random slope. Patient demographics as well as lesion characteristics were also tested for association with growth rate. RESULTS: Among the 80 lesions, 95.0% were diagnosed following RTBs. After a median imaging follow-up of 33.4 months, the lesions had grown by a median of 0.5cm. Overall, 76.3% (n=61) of the lesions had grown. The average annual growth rate was 0.15cm (95% CI: 0.070.23). All in all, 73.8% (n=59) of the lesions have grown by 1cm or less during the following period. Baseline lesion size was significantly associated with growth rate on multi variable analysis (p<0.001). Of the patients diagnosed by biopsy, three had a repeat biopsy during the surveillance period. The initial diagnosis was confirmed in all of them. Of these, one opted for surgery despite the reassuring biopsy findings and the surgical pathology confirmed the diagnosis of oncocytoma. At the time of analysis, four deaths was reported, all from non-renal related causes. Moreover, no patients develop metastasis from their lesion during follow-up. CONCLUSIONS: Despite being considered benign, the majority of oncocytoma will show local progression over time. Regardless of this, oncocytomas can be safely managed with regular imaging following a diagnosis based on RTB. Nonetheless, patients opting for a surveillance strategy should be made aware that a diagnosis of oncocytoma based on RTB is associated with a certain degree of uncertainty due to the difficulty of differentiating them from chromophobe renal cell carcinoma and the possibility of hybrid tumours.
file:///S|/IM/EURSUP/2015%20EAU%20Abstracts/content/data/306.html[19/02/2015 08:10:44]
306
The natural evolution of oncocytomas: Can they be safely followed by surveillance? Eur Urol Suppl 2015;14/2;e306
Print! Print!
Richard P.O. 1 , Jewett M.A.S. 1 , Bhatt J.R. 1 , Timilshina N.1 , Evans A.J.2 , Finelli A. 1 1 Princess
Margaret Cancer Centre, University Health Network and The University of Toronto, Dept. of Surgery and Surgical Oncology,
Division of Urology, Toronto, Canada, 2 Toronto General Hospital, University Health Network and The University of Toronto, Dept. of Laboratory Medicine and Pathobiology, Toronto, Canada INTRODUCTION & OBJECTIVES: Despite the recognition that a large proportion of small renal masses are benign, the vast majority are still being managed by upfront ablative approaches. Many centers have demonstrated that percutaneous renal tumour biopsies (RTBs) is a safe and accurate alternative approach to preoperatively identify the histology of renal cell tumours, including oncocytomas. However, noninvasive methods to reliably differentiate oncocytomas from their malignant counterparts are still lacking. Moreover, little studies on the natural history on oncocytomas have been published. The objectives of this study was to evaluate the growth rate of histologically proven oncocytoma and to improve our understanding of the natural history of these benign lesions. MATERIAL & METHODS: This is single-center retrospective study in which we identified 110 patients diagnosed with an oncocytoma following renal tumour biopsy (RTB) or surgery between 2003 and 2014. Masses with less than 12 months of imaging follow-up were excluded, leaving 80 (72 patients) available for analysis. The average growth rate was estimated using mixed effect linear model adjusted for individual clustering and using a random intercept and a random slope. Patient demographics as well as lesion characteristics were also tested for association with growth rate. RESULTS: Among the 80 lesions, 95.0% were diagnosed following RTBs. After a median imaging follow-up of 33.4 months, the lesions had grown by a median of 0.5cm. Overall, 76.3% (n=61) of the lesions had grown. The average annual growth rate was 0.15cm (95% CI: 0.070.23). All in all, 73.8% (n=59) of the lesions have grown by 1cm or less during the following period. Baseline lesion size was significantly associated with growth rate on multi variable analysis (p<0.001). Of the patients diagnosed by biopsy, three had a repeat biopsy during the surveillance period. The initial diagnosis was confirmed in all of them. Of these, one opted for surgery despite the reassuring biopsy findings and the surgical pathology confirmed the diagnosis of oncocytoma. At the time of analysis, four deaths was reported, all from non-renal related causes. Moreover, no patients develop metastasis from their lesion during follow-up. CONCLUSIONS: Despite being considered benign, the majority of oncocytoma will show local progression over time. Regardless of this, oncocytomas can be safely managed with regular imaging following a diagnosis based on RTB. Nonetheless, patients opting for a surveillance strategy should be made aware that a diagnosis of oncocytoma based on RTB is associated with a certain degree of uncertainty due to the difficulty of differentiating them from chromophobe renal cell carcinoma and the possibility of hybrid tumours.
file:///S|/IM/EURSUP/2015%20EAU%20Abstracts/content/data/306.html[19/02/2015 08:10:44]