Prognostic implications of dominant lesion misidentification in multiple primary lung cancer.

Background: Surgical resection remains the cornerstone of treatment for multiple primary lung cancer (MPLC). Given that the dominant lesion (DL) primarily determines the prognosis of patients with MPLC, accurate identification of the DL is crucial. This study aims to investigate the prognostic impact of preoperative misidentification of the DL on patients with MPLC. Methods: Patients with clinical stage I MPLC between January 2014 and December 2021 were retrospectively collected. The DL was preoperatively identified based on the mean diameter of lesions on computed tomography (CT) images, with postoperative confirmation via pathological examination results. Patients were categorized into the Inconsistent group (IG) if preoperative misidentification of the DL led to two scenarios: (I) a discrepancy between the actual surgical procedure performed and the optimal surgical approach retroactively determined based on postoperative assessment; or (II) prioritized resection of secondary lesions followed by staged resection of the DL. All remaining patients, in whom preoperative DL identification was consistent with postoperative confirmation and surgical procedures aligned with the DL-guided strategy, were assigned to the Consistent group (CG). Propensity score matching (PSM) was implemented to mitigate confounding effects from intergroup clinical characteristic variances. Overall survival (OS) and recurrence-free survival (RFS) were assessed, with prognostic factors evaluated using multivariate cox regression analysis. Results: From an initial cohort of 159 patients, 78 patients were selected through 1:2 PSM. All covariates demonstrated satisfactory balance between groups after matching, with no statistically significant differences observed. Five-year OS rates were 96.15% [95% confidence interval (CI): 91.7-98.3%] for IG and 98.08% (95% CI: 94.2-99.4%) for CG. Corresponding RFS rates were 62.86% (95% CI: 54.8-70.1%) and 91.54% (95% CI: 85.1-95.3%), respectively. Multivariable analysis identified inconsistent surgery [hazard ratio (HR) 5.341; 95% CI: 1.085-26.282; P=0.04] and receipt of postoperative adjuvant therapy (HR 5.613; 95% CI: 1.359-23.174; P=0.02) as independent risk factors of RFS. Conclusions: In patients with MPLC, preoperative misidentification of the DL may potentially affect prognosis due to the difference of surgical approach. Consequently, accurate preoperative identification of DLs is essential for optimizing surgical planning.