Clinical impact of segmental renal vein invasion on recurrence in patients with clinical T1 renal cell carcinoma undergoing partial nephrectomy.

BACKGROUND

This study evaluated the clinical significance of pathological factors associated with T3a upstaging according to the American Joint Committee on Cancer/Union for International Cancer Control 8th edition TNM-staging system in patients with clinical T1 renal cell carcinoma undergoing definitive surgery.

METHODS

We retrospectively investigated 418 patients with renal cell carcinoma who underwent partial or radical nephrectomy at our institution between 2006 and 2016. Surgical specimens were grossly and microscopically re-reviewed with respect to extrarenal extension patterns by two urological pathologists. Kaplan-Meier analysis and Cox regression were used to determine the impact of the factors associated with pathological stage T3a on recurrence-free survival. Harrell's c-index was used to compare the prognostic accuracy of the current and previous staging systems.

RESULTS

Overall, the 5-year recurrence-free survival was 94.5% (median follow-up duration, 60.8 months). Of 418 patients, 46 (11.0%) were upstaged to pathological stage T3a, including 12/267 (4.5%) and 34/151 (22.5%) in the partial and radical nephrectomy groups, respectively. Among these upstaged patients, partial nephrectomy was significantly associated with a higher recurrence rate than radical nephrectomy (5-year recurrence-free survival: 48.9 vs. 83.9%, P = 0.0172). Although perinephric fat invasion had the highest c-index in all patients (0.580-0.679), microscopic segmental renal vein invasion was a significant predictor of recurrence in patients undergoing partial nephrectomy (c-index, 0.60).

CONCLUSION

Assessing microscopic segmental renal vein invasion, which has been included in the current staging system recently, is essential to accurately predict the oncological outcome in the era of partial nephrectomy for clinical T1 renal cell carcinoma.