Impact of histological components on selecting limited lymphadenectomy for lung adenocarcinoma ≤ 2 cm

[Display omitted] •Percentage of histological components (PHC) is a valuable predictor of N2 metastasis.•PHC predicates the procedure-specific risk (limited or systematic lymphadenectomy).•Frozen section may act as a feasible tool for intraoperatively evaluating PHC. There is still some dispute regarding the performance of limited mediastinal lymphadenectomy (LML) even for lung adenocarcinoma ≤ 2 cm. We aimed to recognize the potential candidates who can benefit from LML based on the percentage of histological components (PHC). We analyzed 1160 surgical patients with invasive lung adenocarcinoma ≤ 2 cm from seven institutions between January 2012 and December 2015. All histological subtypes were listed in 5% increments by pathological slices. To test the accuracy of frozen section in judging PHC, frozen section slides from 140 cases were reviewed by three pathologists. There were 882 patients with systematic mediastinal lymphadenectomy (SML) and 278 with LML. Multivariable analysis indicated that, the total percentage of micropapillary and solid components (PHCMIP+S) > 5 % was the independent predictor of N2 metastasis (P 5 % (RFS, HR = 2.143, P