Histology-specific Prognostic Impact of Microscopic Positive Surgical Margins in Renal Cell Carcinoma: Implications for Postoperative Surveillance

Background and objective: Microscopic positive surgical margins (m-PSM) have been associated with adverse outcomes after surgery in renal cell carcinoma (RCC). However, their role in survival outcomes across RCC histologies remains unclear. Our aim was to evaluate the prognostic impact of m-PSM in clear-cell RCC (ccRCC) versus non-clear-cell RCC (nccRCC). Methods: We retrospectively analyzed data for 8270 patients who underwent partial (PN) or radical nephrectomy (RN) for RCC. Patients were grouped as ccRCC or nccRCC (including papillary and chromophobe RCC). Outcomes included overall survival (OS), cancer-specific survival (CSS), and recurrence-free survival (RFS). Kaplan-Meier analysis and multivariable Cox regression (CoxPH) were used to assess associations between m-PSM and survival endpoints according to histology. Key findings and limitations: = 0.024). Limitations include low event numbers in nccRCC and incomplete data on surgical technique detail and adjuvant therapies. Conclusions and clinical implications: In ccRCC, m-PSM showed consistent associations with overall, cancer-specific and recurrence-free survival. By contrast, in nccRCC, m-PSM was statistically associated with recurrence, while no statistically significant association was observed with OS or CSS within the available follow-up. These findings highlight histology-specific associations between margin status and postoperative outcomes, and further research should focus on investigating the prognostic role of positive surgical margins in the non-clear cell setting. Patient summary: We looked at the presence of a microscopic margin positive for tumor after surgery for kidney cancer (KC) and its association with survival. Positive margins were associated with survival outcomes in clear-cell KC, but not in less common histological KC subtypes. Our results provide subtype-specific information on outcomes for these patients after surgery and show that further research is needed for the different KC subtypes.