Introduction

Few studies have evaluated the role of biopsy for large or high stage kidney tumors. The purpose of this study was to determine if pre-treatment biopsy changed management in patients with ≥cT2 renal masses.

Methods

Clinical and pathologic data were reviewed from patients who presented with ≥cT2 renal masses from 2010-2016. Routine biopsy technique included multiquadrant sampling of different regions within the tumor.

Results

From 2010-2016, 277 patients with ≥cT2 renal masses were identified; median tumor size was 8.8 cm (IQR 7.4-11 cm). Percutaneous biopsy was obtained prior to treatment in 150 (54.1%) patients and 127 (45.8%) patients were treated surgically without biopsy. Non-RCC tumors were identified in 21 (14%) of patients in the biopsy cohort and in 16 (12.6%) in the non-biopsy cohort (including angiomyolipoma, sarcomas, metastatic tumors, squamous cell carcinoma, cystic nephroma, Wilms&[prime] tumor, diffuse B-cell lymphoma, mixed epithelial and stromal tumor, Xanthogranulamatous Pyelonephritis and complex cysts). _x000D_ _x000D_ In non-RCC patients who received biopsy, 12 (57.1%) deferred upfront nephrectomy including those treated with neoadjuvant chemotherapy or radiation. For patients with metastatic RCC, 11 patients had sarcomatoid features identified on biopsy. Nine patients deferred upfront cytoreductive nephrectomy for systemic therapy or clinical trial. Six patients without metastatic disease had sarcomatoid features identified on biopsy. In 5/6 patients, more aggressive surgery including bilateral RPLND, was performed _x000D_ _x000D_ Overall, in 130 patients who were surgical candidates, the information gained from biopsy diagnosis changed management from standard upfront nephrectomy in 28 (22%) patients. These patients included 13 patients with non-RCC tumors, 9 patients with mRCC and sarcomatoid features who deferred cytoreductive nephrectomy, and 5 patients with non-metastatic RCC with sarcomatoid features who received more aggressive surgery. No Clavien 2 or greater complications were identified in patients following percutaneous biopsy. _x000D_

Conclusions

Percutaneous biopsy changed management for 1 in 5 of patients with ≥cT2 renal masses by identifying non-RCC renal tumors and RCC with sarcomatoid features.

Funding

none