Conditional survival of patients with nonmetastatic renal cell carcinoma: How cancer-specific mortality changes after nephrectomy

Background: Conditional survival (CS) may reveal important differences in cancer-specific mortality (CSM) among patients with nonmetastatic renal cell carcinoma (nmRCC). This study assessed CS according to T and N stages in patients treated surgically for nmRCC. Patients and Methods: Within the SEER database (2001–2015), all patients with nmRCC treated with either partial or radical nephrectomy were identified. CSM-free estimates according to T and N stage and substage groupings (pT1aN0–pT4N0 and pTanyN1) and multivariable Cox regression models with adjustment for Fuhrman grade and histologic subtype were assessed. Results: According to T and N stage and substage groupings, the following patients were included in the study: 35,966 (46.2%) with pT1aN0 disease; 18,858 (24.2%) with pT1bN0; 5,977 (7.7%) with pT2aN0; 2,511 (3.2%) with pT2bN0; 11,839 (15.2%) with pT3aN0; 1,037 (1.3%) with pT3b–cN0; 402 (0.5%) with pT4N0; and 1,302 (1.7%) with pTanyN1. Conditional CSM-free survival estimates were 98.2% at 1 year versus 98.0% at 10 years of event-free follow-up for patients with pT1aN0 disease, relative to baseline. Conversely, pT4N0/pTanyN1 conditional CSM-free survival estimates were 55.8% at 1 year versus 77.9% at 8 years of event-free follow-up. Attrition due to mortality was highest in patients with pT4N0/pTanyN1 disease. In multivariable Cox regression analyses, T stage, tumor grade, and histologic subtype represented independent predictors, but no interactions were identified. Conclusions: Tumor stage and its substages represent extremely important determinants of prognosis after lengthy event-free follow-up. The recorded observations have critical importance for physicians regarding patient follow-up and counseling.