Impact of tumor disappearance ratio on the prognosis of lung adenocarcinoma ≤2 cm in size: A retrospective cohort study

Background/Purpose Lung cancer patients can have advanced-stages at diagnosis, even the tumor size is ≤2 cm. We aimed to study the relationship between image characteristics, clinical, and patholoigcal results. Methods We retrospectively enrolled patients with lung adenocarcinoma at Taichung Veterans General Hospital and Chang Gung Memorial Hospital from 2007 to 2015, who were diagnosed with treatment naive primary tumor lesions at sizes less than 2 cm, as measured by computed tomography (CT) scans. The patient was analyzed for lymph node (LN) and distant metastasis evaluation, with clinicopathological characteristics, including tumor-disappearance ratio (TDR) (tumor diameter at the mediastinal/lung window) over chest CT scans, pathological diagnosis, disease-free survival (DFS), and overall survival (OS). Results Totally 280 patients were surveyed initially and showed significantly increase of clinical LN involvement and distant metastasis when TDR ≤75% compared with >75% (21.6% vs 0% for LN involvement; 27.1% vs 0% for distant metastasis; both p  Conclusion For lung cancer patients with primary tumor ≤2 cm, TDR ≤75% was related to more advanced stages, the presence of micropapillary or solid components of adenocarcinoma subtypes, worse DFS, and a trend of worse OS.