Recurrence Patterns and Associated Factors After Adjuvant Radiotherapy for Oral Cavity Squamous Cell Carcinoma: A Narrative Review

Oral cavity squamous cell carcinoma (OCSCC) remains a challenging head and neck malignancy with a substantial risk of locoregional recurrence despite surgery followed by adjuvant radiotherapy, with or without chemotherapy. This narrative review summarizes relevant literature on patterns of failure following postoperative radiotherapy for OCSCC, with consideration of the clinical challenges encountered in South Asian and lower-middle-income settings, where a large proportion of patients present with locally advanced disease. Available evidence suggests that recurrences in OCSCC is predominantly an early event, with local and regional failures representing the most frequent patterns, although distant metastases also occur in patients with advanced disease. Failure patterns vary according to oral cavity subsite, tumor stage, pathological risk factors, and treatment characteristics. We observed that a large proportion of recurrences occur within previously irradiated high-dose radiotherapy regions, highlighting the contribution of intrinsic tumor aggressiveness and treatment resistance, while marginal, out-of-field, and contralateral neck failures remain clinically relevant. Adverse features including advanced nodal disease, extranodal extension, perineural invasion, greater depth of invasion, bone involvement, and positive or close surgical margins are associated with increased recurrence risk. In addition, delays in initiating postoperative radiotherapy and interruptions during treatment may adversely affect outcomes. Early multidisciplinary management, appropriate surgical expertise, timely delivery of adjuvant treatment, careful recognition of adverse tumor-related factors, and improved coordination of cancer care remain important for optimizing locoregional control, particularly in resource-constrained settings.