Adjuvant therapy improves survival in pT4aN0 oral cavity squamous cell carcinoma with bone invasion

•Patients with pT4 OCSCC with bone invasion are generally recommended adjuvant therapy•Recent studies suggest that there may not be a survival benefit associated with adjuvant RT/CCRT in these patients•In our study, the patients who received adjuvant RT/CCRT had improved overall and disease-free survival•This survival benefit remained significant after controlling for histopathologic characteristics, including tumor size