The following is a summary of “Validation Study of New IASLC Histology Grading System in Stage I Non-Mucinous Adenocarcinoma Comparing With Minimally Invasive Adenocarcinoma” published in the November 2022 issue of Clinical Lung Cancer by Woo et al.

Specifically, the International Association for the Study of Lung Cancer  (IASLC) has recommended a new histologic grading system for pulmonary non-mucinous invasive adenocarcinoma. Patients at stage I, including those with minimally invasive adenocarcinoma (MIA), were analyzed for its clinical impact on prognosis. Between 2012 and 2019, 919 people with lung cancer received surgery. Stage I patients (n = 500) were retrospectively reviewed. They were classified as 1 of 4 groups: MIA, the 3 new IASLC grades (grades 1-3). Recurrence and death risk variables were identified using Cox proportional hazards analysis. Additionally, researchers compared the IASLC grading system’s predictive power to that of alternative models based on clinicopathologic features (baseline model), TNM staging, and the predominating histologic pattern.

A comparison was made using the area under the receiver operating characteristic curve (AUC). In patients with stage I adenocarcinoma, the IASLC grading system significantly stratified Recurrence-free survival (RFS) and overall survival (OS) (P<.001 and P=.003, respectively). In addition, IASLC grade 3 was an important factor in both RFS (hazard ratio [HR] 3.18, P<.001) and OS (HR 2.31, P=.013) in multivariate analysis. The AUCs of the new IASLC model were 0.781 for recurrence and 0.770 for mortality, compared with those of the predominant pattern (0.769 for recurrence, 0.747 for death) and TNM staging (0.762 for recurrence and 0.747 for death).

The IASLC grading system improved upon prior models in its ability to predict the prognosis of early-stage adenocarcinoma. Therefore, a detailed pathologic investigation for early-stage adenocarcinoma is necessary because the IASLC classification looks to improve the current method.