Conditional survival analysis of patients with resected non-small cell lung cancer

Conditional survival (CS) analyses provide an estimate of survival accounting for years already survived after treatment. We aim to evaluate the difference between actuarial and conditional survival in patients following lung resection for non-small cell lung cancer (NSCLC). In addition, CS analyses are used to examine whether prognosticators of survival change over time following surgery.

Patients who underwent anatomic lung resection at a single institution for pathologic stage I-IIIA NSCLC between 2010 and 2021 were identified; those who underwent wedge resection for node-negative tumors ≤2 cm were also included. CS estimates were calculated as the probability of remaining disease-free after x years of nonrecurrence (CS). Kaplan-Meier, log-rank, and Cox proportional hazard methods for examining CS were used for subgroup comparisons and assessing associations with baseline covariates.

Overall, 863 patients met the study inclusion criteria, with a median follow-up of 44.1 months. Conditional overall survival (OS) and disease-free survival (DFS) were greater than actuarial rates at all time points after surgery. At the time of resection, male sex (hazard ratio [HR], 1.33; 95% confidence interval [CI], 1.03 to 1.72; P = .032), tumor size >3 cm (HR, 1.17; 95% CI, 1.11-1.23; P < .001), node positivity (HR, 3.31; 95% CI, 2.52-4.33; P < .001), and American Joint Committee on Cancer stage (P < .001) were associated with DFS. However, if a patient lived 3 years without recurrence (CS₃), these factors were no longer prognostic of DFS.

Conditional survival analyses provide dynamic assessments of OS and DFS after NSCLC resection. After 3 years without recurrence, certain characteristics associated with DFS at the time of surgery no longer prognosticate recurrence.