Clinical efficacy and safety of tegafur, gimeracil, and oteracil potassium (S-1) monotherapy for incurable oral squamous cell carcinoma patients

Objective

This retrospective study aimed to investigate the overall response rate, survival time, and adverse events (AEs) after S-1 administration for incurable oral squamous cell carcinoma (OSCC) after standard therapy and report the efficacy and safety of S-1 monotherapy.

Patients and methods

This was a retrospective, single-center, cohort study. Twenty-eight patients with incurable OSCC were enrolled. In all patients, S-1 was administered for two weeks followed by a one-week rest. The primary outcome variables were 2-year overall survival (2yOS) and median survival time (MST) after S-1 administration, estimated using the Kaplan-Meier method. Additional outcome variables were the best overall response and AEs leading to S-1 discontinuation.

Results

The overall response rate (ORR) was 35.7 %. Stable disease (SD) was seen in 28.6 %, and the disease control rate (DCR) was 64.3 %. The median duration of S-1 monotherapy was 58.5 days. The 2yOS of all patients was 5.9 %, and MST was 7.1 months. In cases in which disease control (group of complete response, partial response, and SD) was achieved, 2yOS was 8.9 %, and MST was 10.2 months. AEs requiring discontinuation of S-1 occurred in 25.0 % of patients, with grade 3 or 4 neutropenia in 17.9 %, and any grade of drug-induced lung injury in 2 patients (7.1 %)

Conclusions

S-1 monotherapy for incurable OSCC patients could be expected to achieve an ORR of 35.7 % and DCR of 64.3 %, and it is relatively safe to administer. S-1 monotherapy is a treatment worth considering for incurable OSCC patients who have exhausted standard therapy.