The coronavirus disease 2019 (COVID-19) pandemic placed a tremendous burden on lung cancer healthcare providers, prompting them to use approaches that are different from the standards of cancer care. Cancer screening was suspended in the early phase of the pandemic [1], and patients showing cancer symptoms may have been reluctant to seek care at outpatient clinics owing to fear of contracting the infection. Consequently, the number of cancer screenings, diagnostic examinations, and diagnoses for lung cancer decreased during the pandemic [2], [3], [4], [5], [6], [7], [8], [9], [10].

Previous studies conducted in various countries [4], [11], [12], [13], [14], [15], including Japan [16], [17], [18], [19], [20], [21], reported changes in the number of lung cancer surgeries during the pandemic. However, many studies conducted in Japan were single-institution studies [16], limited to specific regions [17], [18], or questionnaire surveys with low response rates [19]. Therefore, these results may not accurately depict the impact of COVID-19 on lung cancer surgery in Japan as a whole. By contrast, the results of studies using the National Clinical Database (NCD) have high generalizability; the NCD contains data on more than 90% of all surgical procedures performed in Japan. Ikeda et al. reported that the number of lobectomy procedures in 2020 was lower than in 2018 and 2019 [20]. Sato et al. reported that the number of surgeries for primary lung cancer decreased in 2020, whereas that for metastatic lung cancer remained unchanged based on the trend over the past 5 years [21]. Several expert committees suggested postponing surgery in patients with non-fatal cancers and considering alternative treatment options to replace or delay surgery, such as stereotactic body radiotherapy (SBRT) and ablation, whenever feasible during the pandemic [22], [23], [24], [25]. However, no study has reported the number of treatments other than surgery for lung cancer in Japan. Given the potential substitution of surgery for lung cancer with alternative treatments during the pandemic, changes in the number of possible alternatives, including SBRT and ablation, merit evaluation.

This study aimed to determine the impact of the COVID-19 pandemic on the treatment of primary and metastatic lung cancer including surgical resection, photodynamic therapy (PDT) or laser ablation, and SBRT in Japan. We used the National Database of Health Insurance Claims and Specific Health Checkups (NDB) of Japan, a nationwide database that contains comprehensive insurance claims data.