Refusal of Guideline-Recommended Adjuvant Therapy in Oral Squamous Cell Carcinoma Is Associated with Less Favorable...

Guideline-recommended adjuvant therapy, including radiotherapy alone or concurrent chemoradiotherapy, is an established component of treatment for patients with high-risk oral squamous cell carcinoma (OSCC). However, a considerable proportion of patients (30.7%) refuse postoperative treatment despite a clear guideline-based recommendation. Data on determinants of treatment refusal and its association with oncologic outcomes remain limited.

This retrospective single-center cohort study included 88 patients with histologically confirmed OSCC and a clear indication for adjuvant therapy between 2015 and 2021. Overall survival (OS) and disease-free survival (DFS) were estimated using the Kaplan-Meier method. Group comparisons were performed using Breslow tests to account for potential early differences in survival. Exploratory Cox proportional hazards models were calculated for OS to assess the association between completion of adjuvant therapy and survival after limited adjustment for clinically relevant covariates.

Refusal of indicated adjuvant therapy occurred in 27 of 88 patients (30.7%) and was significantly associated with older age (p = 0.002) and female sex (p = 0.002). In unadjusted Kaplan-Meier analyses, patients who refused adjuvant therapy showed shorter median OS compared with those who completed treatment, although the difference did not reach statistical significance (p = 0.155). In exploratory Cox regression analyses, completion of adjuvant therapy was associated with a reduced risk of death after adjustment for age and sex (HR 0.22, 95% CI 0.09-0.54; p = 0.001). In the overall cohort, no statistically significant difference in DFS was observed according to adjuvant therapy status (p = 0.129). However, exploratory subgroup analyses suggested that DFS differences according to adjuvant therapy status were more apparent in patients with advanced primary tumors (pT3/4; p = 0.032) and those with more extensive nodal disease (pN2/3; p = 0.019).

Refusal of guideline-recommended adjuvant therapy is frequent in patients with high-risk OSCC and was associated with less favorable survival patterns in this cohort. Given the retrospective design, limited sample size, and exploratory nature of the analyses, these findings should be interpreted as associative rather than causal. Nevertheless, they highlight the potential clinical relevance of treatment adherence and support the importance of patient-centered counseling to improve uptake of guideline-recommended postoperative therapy.