Patterns of Relapse and Implications for Post-Nephrectomy Surveillance in Patients with High Risk Nonclear Cell Renal Cell Carcinoma: Subgroup Analysis of the Phase 3 ECOG-ACRIN E2805 Trial.

Purpose: The natural history of nonclear cell renal cell carcinoma following surgery with curative intent remains poorly defined with postoperative surveillance informed by guidelines largely intended for clear cell renal cell carcinoma. We evaluated relapse patterns and potential implications for post-nephrectomy surveillance in patients with nonclear cell renal cell carcinoma enrolled in the E2805 trial, the largest randomized trial of adjuvant antiangiogenic therapy of high risk renal cell carcinoma.

Materials And Methods: We retrospectively analyzed the records of patients with completely resected nonclear cell renal cell carcinoma. Participants received up to 54 weeks of postoperative therapy with sunitinib, sorafenib or placebo and underwent surveillance imaging at standardized intervals for 10 years. For recurrence rates by site the cumulative incidence was estimated, accounting for competing risks. The adequacy of strict adherence to post-nephrectomy surveillance guidelines was evaluated.

Results: A total of 403 patients with nonclear cell renal cell carcinoma were enrolled in the study. During a median followup of 6.2 years 36% of nonclear cell renal cell carcinomas recurred. Five-year recurrence rates were comparable for nonclear and clear cell renal cell carcinoma in the 1,541 patients, including 34.6% (95% CI 29.8-39.4) and 39.5% (95% CI 36.9-42.1), respectively. However, patients with nonclear cell renal cell carcinoma were significantly more likely to have abdominal sites of relapse (5-year recurrence rate 26.4% vs 18.2%, p = 0.0008) and significantly less likely to experience relapse in the chest (5-year recurrence rate 13.7% vs 20.9%, p = 0.0005). Current surveillance guidelines would potentially capture approximately 90% of relapses at any site.

Conclusions: Nonclear cell renal cell carcinoma may show a distinct pattern of relapse compared to clear cell renal cell carcinoma. Our findings emphasize the importance of cross-sectional, long-term imaging in patients with high risk, resected, nonclear cell renal cell carcinoma.