Relationship between histopathological therapeutic effect and prognosis in oral cancer patients after preoperative S-1 chemotherapy followed by surgery

Objectives Preoperative S-1 chemotherapy is administered to prevent tumor proliferation before surgery in oral squamous cell carcinoma (OSCC). The aim of this study was to investigate the relationship between the histological therapeutic effect and prognosis in patients with OSCC after pre-operative S-1 chemotherapy. Materials and methods Among 461 OSCC cases, 281 patients who received preoperative S-1 chemotherapy were compared with 180 patients that did not receive chemotherapy to determine the histological therapeutic effect in the resected specimens and the differences in relapse-free survival. Results The histological chemotherapeutic effect was well correlated with the subsequent prognosis. In an examination of the combined effect of treatment and ypStage, the groups with good S-1 treatment effects had extremely good prognoses, even if the postoperative resection specimens were within the same ypStage. In a stratified search of patients who received S-1 for more than 7 days and who had a significantly better prognosis than those who did not receive S-1, it was found that the prognosis was significantly better for patients with tongue cancer according to site; furthermore, tongue cancer, age under 70 years of age, male sex, and clinical stage I were factors associated with a significantly better prognosis. Conclusions Even if the postoperative resection specimens were within the same ypStage, the groups that responded to S-1 treatment were considered to have extremely good prognoses. Clinical relevance A good adaptation for S-1 was tongue cancer, and especially tongue cancer with cStage I, male sex, and age less than 70 years old.