IASLC/American Thoracic Society/European Respiratory Society Classification of Lung Adenocarcinoma Has Predictive Value for Recurrence and Survival
In a study reported in the Journal of Clinical Oncology, Hung et al assessed the ability of the 2011 International Association for the Study of Lung Cancer/American Thoracic Society/European Respiratory Society (IASLC/ATS/ERS) adenocarcinoma classification system to predict disease recurrence and survival in completely resected stage I to III lung cancer. The classification system had significant predictive value, with micropapillary- and solid-predominant tumors being associated with poorer outcome.
The IASLC/ATS/ERS classification system for invasive adenocarcinoma recommends use of comprehensive histologic subtyping to semiquantitatively assess histologic patterns in 5% increments in order to define single predominant patterns of lepidic, acinar, papillary, micropapillary, or solid.
In the study, IASLC/ATS/ERS histologic classification was performed in 573 patients with stage I to III adenocarcinoma undergoing resection at Taipei Veterans General Hospital. The predominant histologic pattern was acinar in 33.7% of cases, papillary in 27.1%, micropapillary in 19.5%, solid in 13.6%, and lepidic in 6.1%. The predominant pattern was significantly associated with sex (P < .01), invasive tumor size (P < .01), T status (P < .01), N status (P < .01), TNM stage (P < .01), and visceral pleural invasion (P <.01).
Recurrence Rates
The percentage of recurrence was 17.6% for lepidic-, 27.0% for acinar-, 31.9% for papillary-, 50.5% for micropapillary-, and 52.2% for solid-predominant tumors, with the difference between high-grade (ie, solid and micropapillary) and low-grade tumors (ie, lepidic, acinar, and papillary) being significant (P < .01). Micropapillary- (33.9%) and solid-predominant (27.1%) adenocarcinomas were associated with a significantly greater likelihood of developing initial extrathoracic-only recurrence vs the other subtypes (P < .01).
Overall Survival, Freedom From Recurrence, and Disease-Specific Survival
On multivariate analysis including age, sex, invasive tumor size, TNM stage, visceral pleural invasion, use of adjuvant chemotherapy, and use of adjuvant radiotherapy, micropapillary- or solid-predominant disease vs lepidic-, acinar-, or papillary-predominant disease was associated with significantly poorer overall survival (hazard ratio [HR] = 1.6, P = .01), lower likelihood of freedom from recurrence (HR = 1.5, P = .02), and poorer disease-specific survival (HR = 2.3, P < .01).
Among patients who did not receive adjuvant chemotherapy, solid-predominant adenocarcinoma was associated with poorer overall survival, freedom from recurrence, and disease-specific survival (all P < .01). Among patients who received chemotherapy, the solid-predominant pattern was also associated with significantly poorer overall survival (P =.04) and a trend toward poorer freedom from recurrence (P = .08).
The investigators concluded, “In lung adenocarcinoma, the IASLC/ATS/ERS classification system has significant prognostic and predictive value regarding death and recurrence. Solid-predominant adenocarcinoma was also a significant predictor in patients undergoing adjuvant chemotherapy. Prognostic and predictive information is important for stratifying patients for aggressive adjuvant chemoradiotherapy.”
Wen-Hu Hsu, MD, of Taipei Veterans General Hospital, Taiwan, is the corresponding author for the Journal of Clinical Oncology article.
The study was supported by grants from the National Science Council, Taipei Veterans General Hospital, Veterans General Hospitals and University System of Taiwan Joint Research Program, Yen Tjing Ling Medical Foundation, and KS Lu Lung Cancer Foundation. The study authors reported no potential conflicts of interest.
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