Clinical usefulness of the 3-tier classification according to the proportion of morphological patterns for patients with pathological stage I invasive lung adenocarcinoma.

OBJECTIVES

We classified pathological stage I invasive lung adenocarcinomas according to our 3-tier classification, which was based on the proportion of invasive morphological patterns as follows: (1) patients with each predominant subtype, (2) those with a minor histological subtype, even not the predominant subtype and (3) those without each invasive component. We aimed to evaluate the classification's clinical impact in survival, recurrence, malignant grade, and epidermal growth factor receptor (EGFR) mutational status.

MATERIALS AND METHODS

A total of 1,269 patients with p-stage I lung adenocarcinoma underwent curative surgical resection between January 2008 and December 2017. Of these, 620 patients (48.9%) met the inclusion criteria of this study.

RESULTS

Postoperative recurrence was observed in 81 patients (13.1%). Multivariate analysis showed that vascular invasion (hazard ratio, 2.61; p < 0.001) and p-stage IB (hazard ratio, 2.19; p = 0.001) were significantly associated with an unfavorable RFS, while the presence of acinar component (hazard ratio, 1.64; p = 0.052) or solid component (hazard ratio, 1.60; p = 0.074) were marginally significant. The presence of lepidic or papillary component and the absence of acinar or solid component significantly correlated with an increased proportion of lung adenocarcinomas harboring EGFR mutations.

CONCLUSION

In patients with p-stage I invasive lung adenocarcinoma, it is beneficial to use not only the predominant subtype but analyzing the extent of each histological component based on our classification to predict patient prognoses and form appropriate postoperative follow-up methods.