Histopathological changes in tumor budding between biopsy and resected specimens from patients treated with preoperative S-1 chemotherapy for oral cancer

Background S-1 is an oral anticancer agent containing tegafur, a prodrug of 5-fluorouracil (5-FU). Preoperative S-1 chemotherapy is performed to prevent tumor proliferation before surgery in oral squamous cell carcinoma (OSCC). The aim of this study was to evaluate the effects of preoperative S-1 chemotherapy on tumor budding. Methods We examined 248 cases of OSCC and evaluated the budding scores in biopsy and resected specimens by keratin immunohistochemistry. Results In S-1-untreated patients, the budding scores in resected specimens tended to show a mild increase. S-1 treatment had the effect of lowering the budding score, although some cases with dramatically increased budding scores in resected specimens were found in the early phase of administration. Relapse-free survival showed a significant difference (P < .01) according to the presence or absence of S-1 treatment among patients with high budding scores. Conclusions The present findings indicate that S-1 administration may be more effective in patients with high budding scores than in those with lower budding scores.