Impact of Lepidic Component Occupancy on Effects of Adjuvant Chemotherapy for Lung Adenocarcinoma

Background The prognosis of lepidic predominant lung adenocarcinoma is favorable. We postulated that lepidic predominant tumors might not require postoperative adjuvant chemotherapy. The present study aims to determine whether lepidic component occupancy affects overall survival after postoperative adjuvant chemotherapy for lung adenocarcinoma. Methods Clinical and pathologic data were collected from a database and from the medical records of 964 patients with completely resected lung adenocarcinoma. We assessed the influence of lepidic component occupancy in the tumor on the outcomes of adjuvant chemotherapy. Results Among the patients, 270 received adjuvant chemotherapy and 694 did not, and 415 and 549 had lepidic predominant and non-lepidic predominant tumors, respectively. Adjuvant chemotherapy contributed to better overall survival compared with observation in non-lepidic predominant tumors ( p = 0.025). Multivariate analyses revealed age, sex, stage, lepidic component occupancy, and adjuvant chemotherapy as independent prognostic factors for overall survival. The overall survival was significantly longer for patients with non-lepidic predominant tumors at stages IA, IB, and II-III under adjuvant chemotherapy compared with observation ( p = 0.040, p = 0.007, and p = 0.012, respectively), whereas survival rates were similar for patients with all stages of lepidic predominant tumors even after propensity score matching study. Conclusions Lepidic component occupancy reflected the effect of adjuvant chemotherapy for lung adenocarcinoma. Adjuvant chemotherapy did not have much impact for lepidic predominant tumors and could be considered for non-lepidic predominant tumors even at stage IA.