Risk stratification for distant metastasis after postoperative (chemo)radiotherapy in head and neck squamous cell...

With the emergence of immune checkpoint inhibitors for resectable locally advanced head and neck squamous cell carcinoma (HNSCC), identifying patients most likely to experience distant relapse after standard postoperative treatment has become increasingly important. The purpose of this study was to evaluate recurrence patterns, identify clinicopathological factors of distant metastasis and develop a practical risk stratification model after postoperative radiotherapy (PORT) or chemoradiotherapy (POCRT). We retrospectively analyzed 78 patients with HNSCC who underwent curative-intent resection followed by PORT or POCRT between 2017 and 2024. Distant metastasis-free survival (DMFS) was measured from radiotherapy completion, and the cumulative incidence of distant metastasis was estimated with death as a competing event. The four prespecified risk factors were hypopharyngeal primary site, contralateral cervical nodal metastasis, nodal involvement at level IV or below and extranodal extension. During a median follow-up of 50 months, 39 patients experienced recurrence, and distant metastasis was the most common first failure. Twelve-month DMFS rates in the low- (no factors), intermediate- (1 factor) and high-risk (≥2 factors) groups were 85.8%, 79.3% and 33.3%, respectively. After adjustment for T category, high-risk status remained associated with worse DMFS (hazard ratio [HR], 5.43; 95% confidence interval [CI], 2.24-13.15) and a higher cumulative incidence of distant metastasis (subdistribution HR, 11.86; 95% CI, 3.54-39.76). This simple stratification may help identify patients at high risk of early distant relapse after PORT or POCRT, in whom intensification of postoperative treatment warrants evaluation. Prospective validation is required.