Survival prognostic factors for metachronous second primary head and neck squamous cell carcinoma

We examined the overall survival rates of a national cohort to determine optimal treatments and prognostic factors for patients with metachronous second primary head and neck squamous cell carcinomas (mspHNSCCs) at different stages and sites. We analyzed data of mspHNSCC patients collected from the Taiwan Cancer Registry database. The patients were categorized into four groups based on the treatment modality: Group 1 (control arm; chemotherapy [CT] alone), Group 2 (reirradiation [re‐RT] alone with intensity‐modulated radiotherapy [IMRT]), Group 3 (concurrent chemoradiotherapy alone [irradiation with IMRT]), and Group 4 (salvage surgery with or without RT or CT). We enrolled 1741 mspHNSCC patients without distant metastasis. Multivariate Cox regression analyses revealed that Charlson comorbidity index (CCI) ≥6, stage of second HNSCC, stage of first HNSCC, and duration from first primary HNSCC of