Urologic Oncology Fellow Memorial Sloan Kettering Cancer Center
Introduction: Many small renal masses (SRM) are managed with active surveillance (AS), but the role of percutaneous renal mass biopsy (pRMBx) in the context of AS remains undefined. Recent prospective studies have indicated that systematic use of renal mass biopsy increases the likelihood for intervention (surgery or ablation). We sought to evaluate the implementation and influence of pRMBx on the course of patients managed initially with active surveillance for SRMs in our institution.
Methods: Patients referred to Memorial Sloan Kettering between 2010–2020 for a finding of renal mass who were enrolled in active surveillance as initial management were retrospectively identified. Demographic and clinical characteristics as well as data on timing of ablation or surgery were collected along with all pRMBx data. Univariable Cox regression was used to assess the association between clinical characteristics including age, gender, Charlson index, baseline kidney function, as well as surgeon experience, and the likelihood of undergoing biopsy. Kaplan-Meier curves used to visualize time to biopsy were censored at the time of intervention or last follow-up, defined from the time of diagnosis.
Results: Retrospective review of our single institution database identified 1,308 patients from 2010 to 2020 who were managed initially with active surveillance for renal mass. 55% of the patients were male, 85% white, and the three highest volume renal surgeons accounted to 70% of the patients managed with active surveillance. Within 12 months of diagnosis, there was an 8% overall probability of undergoing biopsy, and the cumulative risk rose to 15% at 6 years of follow-up. Male sex, diabetes, Charlson Comorbidity index 4+, and surgeon were associated with receiving a biopsy on AS, while race and family history were not associated. Notably, undergoing percutaneous renal biopsy resulted a significantly higher rate of undergoing intervention [HR 3.48 (95% CI 2.39, 5.04)] irrespective of biopsy result.
Conclusions: Active surveillance continues to be a mainstay of management for small renal masses. At our center, a low percentage of patients on AS undergo percutaneous renal biopsy, with the presence of comorbidities and high surgical risk as associated factors. Despite variations in practice patterns among surgeons regarding the use of biopsy, the rate of intervention after receiving biopsy was significantly increased overall. It remains unclear whether the role of biopsy can be useful in identifying patients who can avoid immediate treatment.
Source of Funding: MSKCC Sidney Kimmel Center for Prostate and Urologic Cancers
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.jpg "Song Jiang, MD, PHD photo")