Treatment outcomes in head and neck cancer presenting with synchronous primaries - case series.

Background: Head and neck cancer with synchronous primary cancers is rare. There is a paucity of data on HNC with SPC regarding treatment modalities, outcomes, and combined treatment toxicities, creating a challenge for treating clinicians. Materials and methods: We retrospectively screened patients who received head and neck cancer radiotherapy in the Saint Luke's Radiation Oncology Network from July 2017 to July 2024. A synchronous primary cancer was defined as anatomically separate, not a possible metastasis of the first primary cancer and diagnosed within six months of the first primary cancer. Results: We screened 2,971 HNC patients who underwent radiotherapy of which 48 (2%) patients met the inclusion criteria. The median follow-up was 21.9 months and median age was 65 years. The most common SPC sites were lung (46%), oesophageal (13%), then prostate, colon and thyroid (all 6%). The median overall survival for all patients was 28 months. Forty-two (88%) patients completed definitive treatment for both cancers. The median overall survival of patients who completed definitive treatment for both cancers was 30.2 months Conclusions: Patients with HNC and a synchronous primary can be treated curatively to both cancers with a median overall survival of over 2 years. Simultaneous radiotherapy for both cancers can be completed with acceptable toxicity rates even in the setting of overlapping radiation fields.