Rates of adjacent organ invasion in non-metastatic renal cell carcinoma: a population-based study.

INTRODUCTION

Pathological T4 (pT4) renal cell carcinoma (RCC) is defined by adjacent organ invasion. The rate of pT4 and its associated clinicopathological characteristics received little attention in non-metastatic (M0) RCC.

METHODS

Within the Surveillance, Epidemiology, and End Results (SEER) database (2004-2022), we identified M0 RCC nephrectomy patients and assessed pT4 rates.

RESULTS

Of 129,075 M0 RCC nephrectomy patients, 733 (0.6%) harbored pT4 stage. Annual pT4 rates decreased from 1.4% in 2004 to 0.4% in 2022 (p < 0.001). According to tumor size, the pT4 rate was 0.1% in tumors <7 cm and increased from 0.7% in 7-7.9 cm tumors to 6.4% in ≥15 cm tumors (p < 0.001). In patients undergoing radical nephrectomy for tumors ≥7 cm, pT4 rate was 2.5% (578/22,981). According to histology, pT4 rates were 2.3% (376/16,703) in clear-cell RCC, 3.0% (81/2682) in papillary RCC, 1.2% (27/2274) in chromophobe RCC, 6.7% (75/1119) in sarcomatoid dedifferentiated tumors, 13.2% (7/53) in collecting duct carcinomas, and 8.0% (12/150) in other variant histologies (p < 0.001). Compared to pT2-3 patients, pT4 patients more frequently underwent lymphadenectomy (63.3% [366/578] vs. 30.0% [6724/22,403], p < 0.001). Among patients who underwent lymphadenectomy, lymph node invasion was more common in pT4 than in pT2-3 stage (83.6% [298/366] vs. 54.8% [3901/6724], p < 0.001).

CONCLUSION

In M0 RCC, pT4 is rare. It is virtually non-existent in tumors <7 cm. The highest pT4 rates are observed in variant histologies. Compared to pT2-3, pT4 is associated with higher lymphadenectomy use and lymph node invasion rates. Collectively, these findings provide descriptive population-level benchmarks.