Assessing risk and benefit of adjuvant therapy in stage IB NSCLC.

Abstract

e20036 Background: The role of adjuvant treatment in stage IB non–small cell lung cancer (NSCLC) remains controversial. In most patients without high-risk features, active surveillance is the standard strategy following resection. However, for patients with high-risk features, the decision between adjuvant treatment (chemo-immunotherapy (CIO) or chemotherapy (CTX)) and surveillance remains unclear. While immunotherapy entered the lung cancer landscape in 2017, the NCCN guidelines still provide only category 2A recommendations in this context, reflecting the absence of definitive evidence. This study revisits the ongoing debate on the optimal management of this subgroup. Methods: We conducted a retrospective cohort study using the SEER Research Plus database and analyzed patients diagnosed with stage IB NSCLC between 2018–2022. Eligible cases had at least one high-risk feature: vascular invasion, visceral pleural involvement, or unknown nodal status (Nx). Non-primary tumors, cases outside the study window, or missing survival time were excluded, leaving 3,185 patients. Patient demographics and clinical variables were extracted. Overall survival (OS) was measured from diagnosis to death or last contact. Kaplan–Meier curves and log-rank tests assessed unadjusted survival, and multivariable Cox proportional hazards regression estimated hazard ratios (HR) with 95% confidence intervals (CI), adjusting for clinically relevant covariates. Analyses were performed in SEER*Stat (v9.0.41.4) and R (v2025.05.1, RStudio). Results: Among the 3,185 patients, 547 received adjuvant treatment (CIO/CTX), while 2,634 did not. Median age at diagnosis was 70 years; 56% were female, 75% non-Hispanic White, and 57% married; most (88%) resided in urban areas (Table 1). Five-year OS was almost identical between groups (70.3% CIO/CTX vs. 72.5% No CIO/CTX; p = 0.22). Multivariable analysis showed no significant association between adjuvant treatment and mortality reduction (HR 1.12, 95% CI 0.89–1.39). Notably, male sex and rural residence were independently associated with worse survival ( p < 0.05). Conclusions: In this SEER-based analysis, adjuvant treatment (CIO/CTX) did not confer a survival advantage over surveillance in patients with stage IB NSCLC and high-risk features, highlighting the need for prospective randomized studies to clarify the role of adjuvant treatments, especially CIO, in this population. Multivariable Cox proportional hazards analysis for overall survival. HR 95% CI P value Diagnosis year 0.91 (0.84, 0.98) 0.02 Age, years 1.05 (1.04, 1.06) <0.001 Marital status (Married) Single 1.16 (0.99, 1.36) 0.06 Setting (Rural) Urban 0.72 (0.58, 0.89) 0.002 Sex Male 1.58 (1.35, 1.85) <0.001 Chemotherapy (None/Unknown) Yes 1.12 (0.89, 1.39) 0.3 Race (NH-White) NH-Black 1.17 (0.90, 1.53) 0.2 Hispanic 0.89 (0.64, 1.24) 0.5 Other 0.65 (0.48, 0.88) 0.005