A Simplified Version of the IASLC Grading System for Invasive Pulmonary Adenocarcinomas With Improved Prognosis
Yohan Bossé1,2, Andréanne Gagné1, Wajd A Althakfi3
1Institut universitaire de cardiologie et de pneumologie de Québec-Université Laval.
The American Journal of Surgical Pathology
|April 10, 2023
Summary
A new simplified grading system for invasive pulmonary adenocarcinoma shows superior prognostic value compared to the current IASLC system. This simpler classification improves clinical convenience and facilitates widespread implementation for better lung cancer management.
Area of Science:
- Oncology
- Pulmonary Medicine
- Pathology
Background:
- Accurate tumor grading is crucial for effective lung cancer management and treatment selection.
- The International Association for the Study of Lung Cancer (IASLC) introduced a 3-tier grading system for invasive pulmonary adenocarcinoma.
- This system incorporates predominant histologic patterns and a 20% cutoff for high-grade components.
Purpose of the Study:
- To validate the prognostic capability of the new IASLC grading system.
- To compare its performance against a predominant pattern-based system and a simplified IASLC version.
- To assess the clinical utility of simplified grading for invasive pulmonary adenocarcinoma.
Main Methods:
- A retrospective, single-site study analyzing 20 years of lung cancer surgery data.
- Invasive pulmonary adenocarcinomas were evaluated in discovery (n=676) and validation (n=717) cohorts.
- Overall survival after surgery was the primary outcome, with a median follow-up of 7.5 years.
Main Results:
- All three grading systems demonstrated strong and comparable predictive performance.
- The simplified IASLC grading system emerged as the most parsimonious model (log-rank P =1.39E-13).
- This simplified system showed strong association with survival in validation and combined sets (P =5.01E-35).
Conclusions:
- A simpler histologic classification for invasive pulmonary adenocarcinoma outperforms the current IASLC grading system.
- The simplified system is clinically convenient and aids widespread implementation.
- This refined grading approach offers improved prognostic accuracy and patient management strategies.
