ORAL02.05: Understanding Internal Differences in N-Category-Stratified Non–Small Cell Lung Cancer (NSCLC) Survival

Abstract

Nodal staging is significantly prognostic after surgical resection for NSCLC. The IASLC’s NSCLC staging project revealed major intercontinental differences in N-category-stratified survival, especially between Asian and non-Asian populations, but also between non-Asian populations (Table). These differences may indicate differences in cancer biology, but also differences in the thoroughness of nodal examination. Descriptive analysis of 5-year survival after curative-intent NSCLC resection from the Mid-South Quality of Surgical Resection (MS-QSR) cohort (all hospitals in 4 contiguous US Dartmouth Hospital Referral Regions). MS-QSR survival, with sequentially more stringent pathologic nodal staging, was compared to IASLC data. The order of stringency was: all patients, complete (R0) re only (similar to the IASLC cohort), at least 1 mediastinal lymph node examined, 10 or more examined lymph nodes (irrespective of anatomic location), + examination of a mediastinal lymph node, and the examination of at least 3 mediastinal nodal stations (as recommended by the National Comprehensive Cancer Network). Depending on stringency, the eligible MS-QSR analysis population ranged from 2063-778 (Table). MS-QSR survival statistics approximated the IASLC’s American data. There was sequential improvement in the N-category-stratified pN0 and pN1 survival with increasing stringency. pN1 patients with 3 or more mediastinal nodal stations had similar survival to the Asian population, but the pN0 survival did not reach the Asian survival level. Patients without any lymph nodes examined (pNX) had a survival identical to those with pN1. pN2 survival was stable in the R0-resection MS-QSR cohort. The prognostic value of pN-stratification depends on the thoroughness of examination, potentially accounting for intercontinental survival differences. More thorough intraoperative surgical staging and pathologic examination practice must be disseminated to improve the postoperative survival of patients with potentially curable NSCLC. The IASLC staging database should consider imposing more quality curbs in future analytic cohorts.