Background: Adjuvant CTx is the standard of care in stage II and IIIA NSCLC, but its value in AJCC6 stage IB NSCLC (T2N0M0) is unclear. Guidelines suggest consideration of adjuvant CTx for stage IB patients at high recurrence risk, but CTx use is variable. Prior population-based studies lacked NSCLC-specific survival (CSS) and key covariates such as health insurance status. Using a Canadian cohort with universal health care coverage and CSS data, we aimed to identify predictors of use and assess the real-world benefit of adjuvant CTx in stage IB NSCLC. Methods: We examined all patients who underwent surgery for T2N0M0 NSCLC in a large Canadian province between 2004 and 2015 and categorized cases based on receipt of adjuvant CTx within 6 months of curative resection. We identified predictors of CTx receipt with logistic regression. We also identified correlates of overall survival (OS) and CSS using Kaplan-Meier methods and Cox regression. Results: 967 patients met eligibility criteria. Median age was 68 (IQR 61-74) years at diagnosis, 455 (47%) were men, and 164 (17%) received adjuvant CTx. Sex, topology, and laterality were similar in patients treated with or without CTx. Lower age at diagnosis, lower Charlson Comorbidity Index, large cell histology, and tumor size ≥ 4 cm were associated with higher likelihood of CTx receipt (all p< 0.05). In the entire cohort and in the subset with ≥ 4 cm tumors, CTx improved OS but not DSS on univariate analysis. In both groups, CTx did not correlate with OS or DSS on multivariate analysis (Table). Conclusions: Adjuvant CTx does not improve survival in this real-world cohort of T2N0M0 NSCLC patients, even for patients with ≥ 4cm tumors, suggesting that it has a limited role in real-world practice.

m = median; HR = hazard ratio; NR = not reached.