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 vs. 5.5 months among patients who did not (p < 0.001). Ten patients had simultaneous radiotherapy to both cancers with overlapping radiotherapy fields and nine of them finished definitive treatment to both cancers. 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.