The treatment modalities and radiotherapy pattern in patients with primary lung cancer in Japan.

Abstract

e20070 Background: In Japan, lung cancer has high incidence and mortality among all cancers. The study is to understand the existing status of the treatment modalities in Japan, especially for radiotherapy (RT). Methods: This was a retrospective cohort study using the Japan Medical Data Center (JMDC) database. A cohort of adult patients with at least two diagnosis codes of primary lung cancer (ICD-10-CM: C34) during January 1st, 2015-March 31st, 2023, and initiated lung cancer treatment was included in the study. The initial treatment episode was defined as a period with the first single or multiple treatments before a 90-day gap. Patients were followed up until a record of death, or the last enrollment in JMDC. The cohort was stratified into four exclusive groups: Group A: ≥1 record of distant metastasis; Group B-1: ≥1 record of regional metastasis; Group B-2: no record of surgery and no metastasis; Group C: ≥1 record of surgery and no metastasis. The characteristics, initial treatment episode and RT patterns were described across the four groups. Results: A total of 9,373 patients were included, with Group A 1,625 (17.3%), Group B-1 527 (5.6%), Group B-2 2084 (22.2%), and Group C 5137 (54.8%). The median follow-up was 21.2 months of the cohort. The median (IQR) time to initial treatment episode from the initial diagnosis was 27 (27), 35 (40), 34 (47) and 38 (36) days for the four groups, respectively. Most of patients in group A (74.1%), B-1 (70.8%), and B-2 (67.6%) had a >3 months duration of initial treatment, and only 32.7% in group C. For treatment involved in the initial treatment episode, RT was accounted for 59.2%, 29.8%, 43.4%, and 4.7% in four groups respectively. For treatment categories in Groups A, B-1, and B-2, RT only was performed in 15.5%, 2.2% and 6.9% of patients with single treatment; and RT was commonly performed with chemotherapy in multiple treatments, with proportions of 83.6%, 95.3% and 95.6% among no surgery. For RT with chemotherapy group, the median RT fractions are 22, 36 and 42, covering a median duration of 35, 43 and 43 days of RT. Conclusions: In Japan, the initial treatment episode usually starts in 30 days and lasts more than 3 months for metastasis and unresectable primary lung cancer. RT only is not commonly performed, and RT with chemotherapy is commonly performed in initial treatment episode. [Table: see text]