Predicting Oncologic Outcomes in Small Renal Tumors

Area of Science:

• Urology
• Oncology
• Pathology

Background:

• Most patients with renal cancer have small renal masses (SRMs), often low-risk.
• A subset of small renal cell carcinomas (SRMs) can exhibit aggressive behavior.
• Identifying aggressive features in SRMs is vital for refining active surveillance protocols.

Purpose of the Study:

• To enhance prognostic models for predicting metastasis-free survival after nephrectomy for SRMs.
• To analyze clinicopathologic characteristics of SRMs associated with adverse outcomes.
• To identify features of aggressive behavior in SRMs.

Main Methods:

• Retrospective analysis of consecutive patients with surgically resected SRMs (≤4 cm) from 1998-2020.
• Evaluation of SRM tumor-forming ability in mice as an indicator of aggressiveness.
• Examination of clinicopathologic factors, including BAP1 immunohistochemistry, associated with metastasis.
• Multivariable Cox proportional hazard regression for metastasis-free survival prediction.

Main Results:

• Of 1720 small renal cell carcinomas (SRM-RCC), 37 (2%) developed metastases.
• Metastatic SRM-RCC showed aggressive morphologic phenotypes and comparable mouse engraftment rates to larger tumors.
• BAP1 loss was significantly associated with metastasis-free survival, independent of TNM stage and SSIGN score.

Conclusions:

• Clinicopathologic features influencing metastasis-free survival in patients with SRM-RCC were identified.
• These findings, upon independent validation, can aid in patient prognosis and active surveillance strategies.
• Features of aggressiveness in small renal tumors that impact post-surgery metastasis likelihood have been identified.