The Grading System of Lung Adenocarcinoma: Ever-Evolving Concepts

We are thankful to Li et al. for their interest and commentary on our study validating the novel International Association for the Study of Lung Cancer grading system for invasive pulmonary adenocarcinoma (ADC).1 Their main concern centered on the relatively high proportion of patients upgrading to grade 3 on the basis of the novel grading system2 in our study. The architectural grading system only refers to the predominant histologic pattern, but most ADCs exhibit heterogeneous compositions. Moreover, the International Association for the Study of Lung Cancer grading system further classifies complex glandular patterns as high-grade patterns.