Real-world evidence of postoperative adjuvant chemotherapy in patients with stage IA–IIIA non-small cell lung cancer in Japan

More insights into the actual, post-2010s status of adjuvant chemotherapy (ATx) induction for non-small cell lung cancer (NSCLC) are needed. This retrospective observational cohort study investigated treatment trends and annual ATx induction rates per stage after complete resection of stage IA–IIIA (Union for International Cancer Control 7 th Edition) NSCLC. Health claims, administrative, and Diagnosis Procedure Combination data, a case-mix patient classification developed in Japan, were collected (1 January 2010–31 March 2022). Proportions and time-to-event outcomes were analyzed (Kaplan–Meier method). Of 62,447 patients, 16,772 (26.9%) received ATx, and 45,675 (73.1%) did not. Data for 2010‒2012 were limited; only data for 2013‒2021 were considered interpretable. From 2013 to 2021, the annual ATx induction rate generally remained constant (stage IA: 15.3%‒18.6%; stage IB: 37.2%‒42.4%; stage IIA: 39.6%‒46.9%; stage IIB: 35.9%‒42.6%; stage IIIA: 45.6%–55.0%). The most common treatments per stage followed the Japan Lung Cancer Society guideline recommendations; however, regimens other than the recommended ones were also used: for example, cisplatin combination therapy in stage IA/IB (8.8%–15.0%/7.7%–19.5%), carboplatin combination therapy in stage IA (7.2%–11.9%)/IB (6.9%–11.9%)/IIA (19.3%–36.6%)/IIB (21.8%–33.7%)/IIIA (28.8%–38.1%), and tegafur-uracil in stage IIB/IIIA (3.3%–21.7%/3.4%–8.8%). Older patients, those with lower body mass index and more complications, and women were less likely to receive ATx, whereas smokers and those treated at designated cancer hospitals were more likely to receive ATx. No significant numerical changes occurred in annual ATx induction rates for stage IA–IIIA NSCLC throughout the study period.