The effect of postoperative adjuvant chemotherapy on survival outcomes in patients with early stage oral squamous cell carcinoma.

The role of adjuvant chemotherapy (Adjuvant CT) in early-stage oral squamous cell carcinoma (OSCC) remains unclear; this study aimed to fill this gap by examining the association between Adjuvant CT and survival outcomes in patients with early-stage OSCC who underwent surgery. A retrospective cohort study was conducted to examine patients diagnosed with early-stage OSCC who underwent surgery between 2004 and 2021. Data were obtained from the Surveillance, Epidemiology, and End Results (SEER) database for evaluating the survival outcomes of individuals who received Adjuvant CT compared to those who did not. To assess the relationship between Adjuvant CT and survival outcomes, statistical methods, including Cox regression analysis, propensity score matching (PSM), and Kaplan-Meier survival analysis were utilized. A total of 18,532 patients were included, with 2,098 (11.3%) receiving Adjuvant CT. Kaplan-Meier analysis showed that age, sex, tumor site, income level, pathological grade, pT status, neck dissection and radiation were associated with prognosis (P < 0.05). Notably, Adjuvant CT was associated with worse overall survival (OS) and disease-specific survival (DSS) compared to no chemotherapy (5-year OS: 63.1% vs. 72.9%; 10-year OS: 47.6% vs. 57.8%, P < 0.0001; 5-year DSS: 71.3% vs. 85.3%; 10-year DSS: 61.6% vs. 81.7%, P < 0.0001). Consistently, after PSM, Adjuvant CT did not improve outcomes in patients with early-stage OSCC (DSS: P = 0.0001; OS:P = 0.00066). Cox regression analysis indicated no overall survival benefit from Adjuvant CT in early-stage OSCC. However, subgroup analysis suggested potential benefits for patients with poorly differentiated tumors. Our study revealed that postoperative Adjuvant CT provides minimal survival benefits for early-stage OSCC patients, though subgroup signals observed. Although the result of the subgroup analysis show that Adjuvant CT may benefit those with poorly differentiated tumors, further research is needed to identify specific subgroups that may benefit.