A retrospective clinicopathological study of lung adenocarcinoma: Total tumor size can predict subtypes and lymph node involvement.

•We validated the predictive impact of the total tumor size on adenocarcinoma subtype and lymph node involvement.•Total tumor size of 1.15cm achieved a sensitivity of 84.44% and specificity 81.4% for differentiating AIS/MIA from IAC.•Total tumor size of 1.05cm achieved a sensitivity of 100% and specificity 50% for lymph node involvement.•The systematic nodal dissection would be unnecessary if total tumor size is ≤1cm in diameter in lung adenocarcinoma patient.