Clinical Outcomes of Postoperative Three-weekly Cisplatin for High-risk Head and Neck Squamous Cell Carcinoma

Background/Aim: Microscopic positive margins and extranodal extension are established pathological risk factors for recurrence after curative surgery for head and neck squamous cell carcinoma. Postoperative radiotherapy with concurrent cisplatin is the standard treatment for such patients. We evaluated the outcomes of postoperative radiotherapy administered concurrently with three-weekly cisplatin and explored factors associated with disease-free survival. Patients and Methods: We retrospectively analyzed patients with head and neck squamous cell carcinoma who started postoperative radiotherapy with concurrent cisplatin between April 2015 and December 2023. Eligible patients had microscopic positive margins or extranodal extension and received postoperative radiotherapy concurrently with three-weekly cisplatin. The primary endpoint was disease-free survival. Secondary endpoints included overall survival, recurrence patterns, and factors associated with disease-free survival. Results: We included 83 patients (median age, 62 years; 68 men). The 5-year disease-free and overall survival rates were 55.5% and 67.9%, respectively, and neither median was reached. Distant metastasis developed in 23 patients (27.7%), with 1-year and 5-year cumulative rates of 21.3% and 28.8%, respectively. In univariate analysis, radiotherapy dose <60 Gy, perineural invasion, and venous invasion were associated with poorer disease-free survival. Disease-free survival did not differ according to cumulative cisplatin dose (≥200 vs. <200 mg/m2). Conclusion: Postoperative radiotherapy administered concurrently with three-weekly cisplatin was associated with 5-year disease-free and overall survival rates of 55.5% and 67.9%, respectively, in routine clinical practice. Perineural and venous invasion may provide additional prognostic information beyond established high-risk pathological features. The frequency of distant metastasis suggests the need for strategies that improve both locoregional and systemic control.