Histologic Grade 3 in Stage 1A Lung Adenocarcinoma: Survival Risks Comparable to Stage 1B

Area of Science:

• Oncology
• Pathology
• Thoracic Surgery

Background:

• Non-small cell lung cancer (NSCLC) recurrence risk persists post-surgery.
• Histologic grading systems aim to improve prognostic accuracy.
• The International Association for the Study of Lung Cancer (IASLC) grading system identifies high-grade tumors.

Purpose of the Study:

• To evaluate the prognostic significance of histologic grade 3 in stage IA non-mucinous lung adenocarcinoma.
• To compare the outcomes of stage IA grade 3 tumors with stage IB tumors.

Main Methods:

• Retrospective analysis of 729 patients with stage I non-mucinous adenocarcinoma (2010-2017).
• Tumor grading based on the IASLC system.
• Kaplan-Meier survival analysis and Cox proportional hazards models for overall survival (OS) and disease-free survival (DFS).

Main Results:

• Stage IA grade 3 tumors had significantly worse OS and DFS than grade 1 and 2 tumors (p < 0.001).
• Survival for stage IA grade 3 was comparable to stage IB (OS p = 0.677, DFS p = 0.248).
• Histologic grade 3 demonstrated risk stratification power comparable to pleural invasion.

Conclusions:

• Histologic grade 3 in stage IA non-mucinous adenocarcinoma identifies high-risk patients.
• These findings suggest grade 3 may refine staging and guide adjuvant therapy decisions.
• Further validation studies are recommended.