Evaluation of renal mass biopsy risk stratification algorithm for robotic partial nephrectomy - Could a biopsy have guided management?

Purpose: We evaluated a published biopsy directed small renal mass management algorithm using a large cohort of patients who underwent robotic partial nephrectomy for tumors 4 cm or smaller.

Results: Patients were assigned to the pathology risk groups of benign (23%), favorable (13%), intermediate (51%) and unfavorable (12%). Patients were also assigned to the management groups of benign pathology (275, 23%), active surveillance (336, 29%) and treatment (564, 48%). Most of the 611 (52%) patients in the benign or active surveillance groups were low surgical risk and had safe treatment (2.6% high grade complications). A biopsy may not have been feasible or accurate in some tumors that were anterior (378, 32%), hilar (93, 7.9%) or less than 2 cm (379, 32%). Of 129 (11%) high surgical risk patients the biopsy algorithm assigned 70 (54%) to benign or active surveillance groups.

Conclusions: The theoretical application of a biopsy driven, risk stratified small renal mass management algorithm to a large robotic partial nephrectomy database suggests that about half of the patients might have avoided surgery. Despite the obvious limitations of a theoretical assumption of all patients receiving a perfect biopsy, the data support the emerging role of renal mass biopsies to guide management, particularly in high surgical risk patients.

Materials and Methods: A simplified algorithm of biopsy directed small renal mass management previously reported using risk stratified biopsies was applied to 1,175 robotic partial nephrectomy cases from 5 academic centers. A theoretical assumption was made of perfect biopsies that were feasible for all patients and had 100% concordance to final pathology. Pathology risk groups were benign, favorable, unfavorable and intermediate. The algorithm assigned favorable or intermediate tumors smaller than 2 cm to active surveillance and unfavorable or intermediate 2 to 4 cm tumors to treatment. Higher surgical risk patients were defined as ASA® 3 or greater and age 70 years or older.