Real-world Treatment Patterns and Clinical Outcomes among Elderly Patients with Locoregionally Advanced Head and Neck Squamous Cell Carcinoma in the United States

Dandan Zheng^1*Su Zhang²Behzad Bidadi³Nati Lerman³Yan Song²Rui Song²Jiayang Li²Anyu Zhu²Yuexin Tang¹James Signorovitch²Sanjay Merchant¹Glenn J Hanna⁴

• ¹Outcomes Research, Merck & Co., Inc., Kenilworth, New Jersey, United States
• ²N/A, Analysis Group (United States), Boston, United States
• ³Oncology Late Stage Development, Merck & Co., Inc., Kenilworth, New Jersey, United States
• ⁴Center for Head and Neck Oncology, Dana–Farber Cancer Institute, Boston, Massachusetts, United States

Introduction: Multimodal therapy, including resection followed by adjuvant radiotherapy (RT) ± systemic therapy (ST) or definitive RT±ST, is recommended for patients with locoregionally advanced head and neck squamous cell carcinoma (LA HNSCC) treated with curative intent. We assessed the real-world use of treatments and associated survival among elderly patients with LA HNSCC receiving surgical or non-surgical primary treatment. Methods: Linked SEER-Medicare data were used to identify patients with newly diagnosed stage III-IVB LA HNSCC (2007-2019) who received primary treatment within 4 months after initial diagnosis. Real-world event-free survival (rwEFS) and overall survival (rwOS) from index (primary treatment initiation) were described using Kaplan-Meier estimates. Correlations between rwEFS and rwOS were investigated by normal scores rank. Landmark analysis was conducted using Cox proportional hazards models to compare rwOS by recurrence in the first year post-index. Results: Of 2180 patients, 626 and 1554 were categorized into the resected and unresected cohorts, respectively (median follow-up: 20.8 and 22.6 months). Overall, the mean age at diagnosis was 74.3 years, 65.9% were male. Over half (56.3%) with resected tumors received RT±ST post-surgery while 64.9% with unresected tumors received definitive RT+ST. The resected cohort had median rwEFS of 7.8 (95% CI: 6.4, 8.7) months and median rwOS of 31.4 (25.2, 40.1) months. The unresected cohort had median rwEFS of 10.0 (9.4, 10.9) months and median rwOS of 32.4 (28.5, 36.7) months. There was a significant positive correlation between rwEFS and rwOS for the resected (r [95% CI]: 0.69 [0.63, 0.73]) and unresected (0.68 [0.63, 0.73]) cohorts (both p<0.001). In the resected cohort, there was a trend of lower rwOS with recurrence first year post-index versus without recurrence (adjusted HR [95% CI]: 1.31 [0.96, 1.80]); in the unresected cohort, the association was significant (1.91 [1.60, 2.29]).Conclusion: In elderly patients with LA HNSCC, surgery followed by RT and definitive RT+ST were the most common treatments in the resected and unresected cohorts, respectively. The suboptimal survival highlights the unmet need for more effective therapies. The positive associations between rwEFS and rwOS in both cohorts support EFS as a predictor of OS when OS data are immature in LA HNSCC.