117P Prognostic value of new grading system in resected lung adenocarcinoma after neoadjuvant therapy

Abstract

A new grading system for resected invasive pulmonary adenocarcinoma was proposed by the International Association for the Study of Lung Cancer (IASLC) pathology committee and validated as a strong prognostic indicator. Nonetheless, the efficacy of pathological evaluation of residual adenocarcinoma proportion using this grading system in prognosis assessment of patients treated with neoadjuvant therapy still needs elucidating. A single-center retrospective study enrolling patients with resected adenocarcinoma receiving neoadjuvant therapy from August 2012 to December 2020 in Shanghai Pulmonary Hospital was conducted. Patients with pathologically proven invasive mucinous adenocarcinoma, receiving immunotherapy or adjuvant radiotherapy, or achieving pathologic complete response (pCR) were excluded. All the surgical specimens were re-evaluated and graded according to the IASLC system for invasive adenocarcinoma. The prognostic value of the new grading system was further validated through Cox proportional hazard models and Kaplan-Meier estimates. A total of 198 patients were enrolled, and were subdivided into 3 cohorts according to the new grading system. There were 13, 37 and 148 patients belonging to grade 1, 2 and 3, respectively. New grading system was evaluated significant (p < 0.001) in univariable Cox analysis of RFS in the entire cohort along with neoadjuvant and adjuvant regimens, STAS presence, ypN stage and MPR status, while only new grading system (p = 0.001) and ypN stage (p = 0.005) were significant prognostic indicator in multivariable analysis. New grading system was further demonstrated significant (p = 0.002) in multivariable Cox analysis of the entire cohort regarding OS. Similar results were also obtained in the non-MPR cohort, where new grading system was evaluated significant in both univariable (p < 0.001) and multivariable analysis of RFS (p = 0.024). Nonetheless, such system was only significant in univariable analysis of OS concerning non-MPR cohort (p = 0.001). The efficacy of pathological evaluation of the residual proportion of lung adenocarcinoma post neoadjuvant therapy using novel grading system was preliminarily verified feasible. Such grading system might assist prognostic evaluation of neoadjuvant cohort other than traditional pathological parameters.