Introduction

Pathologic diagnosis of cancer in renal masses allows for optimal patient selection before treatment and appropriate follow-up after thermal ablation. However, biopsy is still often performed at the same time as ablation and pathologic findings are either non-diagnostic or benign in 7-45% of tumors in large ablation series. The objective of this study was to compare findings for renal mass biopsies obtained prior to treatment (priorbx) to biopsies obtained on the same day as ablation (samedaybx).

Methods

An institutional database identified consecutive patients with renal masses treated with thermal ablation from 2001-2015. Patients treated_x000D_ without biopsy (37) were excluded. Radiologic tumor and patient data were reviewed. Fischer’s exact or chi-square tests were used to evaluate differences between groups, non-diagnostic biopsy rate and the rate of ablation for benign tumors._x000D_

Results

A total of 280 renal tumors were treated with ablation including 197 (70.4%) with priorbx and 83 (29.6%) with samedaybx. There was nodifference in patient or tumor characteristics between samedaybx and priorbx groups (table). Priorbx patients had longer skin-to-tumor distance median 10.5 vs. 8cm, p=0.0001._x000D_ _x000D_ Non-diagnostic biopsy findings were significantly more common in patients with samedaybx compared to priorbx, 14.5% vs. 1.5%, p<0.001. Ablation of_x000D_ oncocytoma was also more common in patients with samedaybx compared to priorbx, 15.7% vs. 3.0%, p<0.001.RCC diagnosis was obtained in only 69.9% of tumors with samedaybx compared to 95.4% of tumors with priorbx, p<0.001._x000D_

Conclusions

Pre-ablation biopsy is associated with a decreased rate of treatment for benign and unidentified renal tumors and better diagnostic_x000D_ yield than same day renal biopsy. This approach has clear benefits to patients considering thermal ablation of small renal masses._x000D_

Funding

None