RÉSUMÉ
Purpose To investigate the clinicopathological characteristics and prognostic correlation of the WHO(2021)new grading system of invasive pulmonary adenocarcinoma in stageⅠ pulmonary adenocarcinoma.Methods The clinical data of 447 patients with stage Ⅰ pulmonary adenocarcinoma were collect-ed,and all cases were evaluated according to the new grading system for invasive pulmonary adenocarcinoma.The immunohis-tochemical EnVision two-step method and elastic fiber staining were used to analyze the clinicopathological features with review of the relevant literature.Results In 447 patients with stage Ⅰlung adenocarcinoma,Napsin A and TTF-1 expression were posi-tive,p40 expression was negative,and Ki-67 proliferation index was higher than 5％in 177 patients(39.6％).There were 39 cases(8.7％)of positive pleural invasion in the visceral layer revealed by elastic fiber staining.The pleural invasion in stage Ⅰpulmonary adenocarcinoma patients was significantly higher than that in grades 2 and 3,the difference was statistically significant(P＜0.05).Patients with different grades of stage Ⅰ pulmonary adenocarcinoma were associated with gender,smoking history,surgical mode,chemotherapy,targeted medication,clinical stage,pathological classification,degree of differentiation,tumor size,vascular invasion,visceral pleural invasion,spread through air space(STAS)and Ki-67 index(P＜0.05).Survival analy-sis showed that there were statistically significant differences in disease free survival(DFS)and overall survival(OS)among different grades(grade 1＞grade 2＞grade 3)(P＜0.05).Cox regression analysis showed that WHO(2021)new grading of invasive pulmonary adenocarcinoma,visceral pleural invasion and Ki-67 proliferation index were independent risk factors for prognosis of patients with stage Ⅰ pulmonary adenocarcinoma.Conclusion The WHO(2021)new grading system of invasive pulmonary adenocarcinoma has good prognostic significance for stage Ⅰ pulmonary adenocarcinoma,and appropriate intervention for high-risk patients.It can effectively assist its postoperative treatment and has application value.