S-1 is an oral fluoropyrimidine agent used for the treatment of non-small-cell lung cancer (NSCLC). Although S-1 monotherapy has been reported to exhibit lesser hematotoxicity compared with other third-generation chemotherapeutics, digestive toxicity was also frequently observed. Alternate-day administration of S-1 has shown a lower rate of severe digestive toxicity than the daily standard administration in patients with NSCLC. However, the safety of alternate-day S-1 therapy in elderly patients aged 75 years or older has not been investigated. The present study was a multi-center and prospective feasibility study aimed to evaluate the safety of alternate-day S-1 therapy in elderly patients with NSCLC. The patients received S-1 orally twice daily for 4 days (Monday, Wednesday, Friday, and Sunday) every week until disease progression or unacceptable toxicity. The primary endpoint was safety, which was evaluated as the number of grade ≥3 adverse events, and the secondary endpoints were progression-free survival (PFS), 1-year survival, and disease control rate (DCR). A total of 10 patients were enrolled, but 2 patients failed to initiate the treatment protocol. Finally, 8 patients were treated with the study protocol regimen. No grade 3 or higher adverse events were observed. Four (50%) and 1 (12.5%) patient had grade 2 or lower digestive symptoms such as anorexia, diarrhea, or stomatitis and grade 1 lacrimation, respectively. Moreover, 2 (25%), 1 (12.5%), and 1 (12.5%) patients had grade 2 renal dysfunction, grade 2 ileus, and elevated blood bilirubin, respectively. The median PFS was 1.5 months (95% confidence interval: 0.9-1.8), and the 1-year survival rate was 42.9%. The DCR was 12.5%. In conclusion, alternate-day S-1 administration can be a safe treatment regimen for elderly patients with NSCLC, but its therapeutic efficacy and safety for elderly patients with NSCLC should be compared against the standard S-1 administration in a large-scale study.
Keywords: S-1; alternative day administration; chemotherapy; elderly patient; non-small-cell lung cancer; prospective feasibility study.