Impact of non-tumor size related features on staging in non-small cell lung cancer: a population-level analysis of the SEER-medicare database.

The objective of this study was to quantify and characterize the presence of non-tumor size features among non-small cell lung cancer (NSCLC) patients in a surgical cohort versus those in a non-surgical cohort and assess the potential impact of key features on staging. A total of 22,876 patients aged 66 years and older with newly diagnosed (2010-2015) stage I-III NSCLC (T1-T3, N0/N1, M0) without prior or concurrent primary cancer were identified from the Surveillance, Epidemiology, and End Results (SEER)-Medicare Database. Reported T stage data (American Joint Committee on Cancer 7th Edition) were compared with a hypothetical tumor size only T stage (Tsize-Only), which did not account for non-tumor size defining characteristics. Frequencies of key non-tumor size features were analyzed among surgical and non-surgical cohorts. In the surgical cohort, a lower Tsize-Only SEER-reported T stage was observed in 2,531 patients (20.8%). Specifically, T stage would be lower in 1,542 (32.6%) patients with T2 disease and in 989 (66.4%) patients with T3 disease. In the non-surgical cohort, lower Tsize-Only Reported T was observed in 1,446 patients (13.5%) [342 (8.8%) patients with T2 disease and 1,104 (60.1%) patients with T3 disease]. The largest disparity between cohorts was in T2 disease and visceral pleural invasion (VPI): VPI was identified in 87.5% of surgically resected patients with lower Tsize-Only versus only 37.4% in non-surgical patients. Our findings highlight the need for better T stage characterization in non-surgical patients. Development of predictive models or standardized radiographic methods to accurately identify VPI in the non-surgical NSCLC population are recommended in light of the established impact of VPI on clinical outcomes. Trial investigators should consider the potential impact of un-identified VPI on their effect size estimates and sample size calculations. Attention towards non-tumor size related features, particularly VPI, may lead to improved treatment decisions and outcomes.