Locoregional treatment of primary tumor in synchronous metastatic head and neck squamous cell carcinomas.

Purpose: Patients with synchronous metastatic head and neck squamous cell carcinomas (mHNSCC) are at risk of locoregional progression associated with significant morbidity and mortality. The aim of this study is to assess whether the addition of aggressive locoregional treatment to systemic therapy could be associated with an improved overall survival (OS) compared to systemic therapy alone in upfront mHNSCC patients.

Material And Methods: This retrospective study included patients presenting with previously untreated mHNSCC who underwent first-line systemic therapy at a single institution between 1998 and 2018. Locoregional treatment was defined as either exclusive locoregional radiotherapy (RT) or surgery with or without adjuvant RT.

Results: One hundred forty-eight patients were included. Eighty patients were treated with systemic therapy alone and 68 patients were treated with a combination of locoregional treatment and systemic therapy. Median overall survival (OS) was 13 months [10.7-15] and median progression free survival (PFS) was 7.7 month [6.5-8.9]. The addition of a locoregional treatment to systemic therapy compared to systemic therapy alone was associated with improved survival (1-year OS, 65.8% vs. 41.1%,  < .001, and 1-year PFS, 42.5% vs. 18.5%,  < .001). Moreover, RT dose equal to 70 Gy was associated with even longer OS compared to a RT dose below 70 Gy and to no locoregional treatment (23.4 vs. 12.7 vs 7.5 months respectively). In a subgroup analysis on 75 patients presenting with a responding or stable metastatic disease after first-line systemic therapy, oropharyngeal primary tumor site and the addition of a locoregional treatment, especially a high radiation dose of 70 Gy, were evidenced as independent prognostic factors for improved OS.

Conclusion: The addition of a high-dose RT locoregional treatment to systemic therapy is associated with prolonged OS in patients with synchronous mHNSCC and should be discussed for patients who respond to or have a stable disease after first-line systemic therapy.