ESTRO meets Asia 2024 - Abstract Book

S185

Interdisciplinary – Head & neck

ESTRO meets Asia 2024

Purpose/Objective:

The purpose of this study was to evaluate the prognosis of elderly patients with locally advanced head and neck squamous cell carcinoma (LA-HNSCC) who received definitive concurrent chemoradiotherapy with weekly cisplatin (CRT) or radiotherapy (RT).

Material/Methods:

We retrospectively analyzed patients aged 70 or older who received CRT or RT for LA-HNSCC in two institutions between April 2014 to December 2022. The inclusion criteria were as follows: (1) patients whose primary tumor site was oropharynx, hypopharynx, or larynx, and (2) patients with clinical stage III, IVA, or IVB based on the Union for International Cancer Control staging system 7th edition. The exclusion criteria were as follows: (1) patients previously treated with surgery before CRT/RT and (2) patients who received concurrent chemotherapy except for weekly cisplatin (40 mg/m 2 ). Differences in characteristics between the CRT and RT group were investigated by the Fisher’s exact test. We calculated overall survival (OS), loco-regional control (LRC), and distant metastasis-free survival (DMFS) by the Kaplan-Meier method. The influence of clinical parameters on OS, LRC, and DMFS was analyzed using the Cox proportional hazards model. Acute adverse events (AEs) were investigated based on Common Terminology Criteria for Adverse Events v. 5.0. P values < 0.05 were considered statistically significant. Seventy patients met the inclusion criteria, of which 13 met the exclusion criteria; 57 were taken forward for final analysis. Twenty-eight patients received CRT, and 29 patients received RT. Median follow-up periods were 20.1 months in the CRT group and 18.1 months in the RT group. The median prescribed dose was 70 Gy in 35 fractions. The median cumulative dose of cisplatin was 200 mg/m 2 . Significant differences between the CRT and RT groups were found in age (median: 73 vs. 80), performance status (0 or 1: 100% vs. 90%), and the use of intensity modulated radiotherapy (93% vs. 66%). There was a trend between the CRT and RT group in the primary tumor site (the proportion of hypopharynx: 64% vs. 38%), N stage (N2a–N3b: 61% vs. 48%), and clinical stage (IVA–IVB: 72 vs. 55%). No significant differences were identified between the CRT and RT group for p16 status (positive: 18% vs. 24%). The 2-year OS, LRC, and DMFS rates in the CRT and RT group were 83/66%, 55/74%, and 71/61%, respectively; there were no significant differences in OS, LRC, and DMFS between the groups (Fig. A, B). Univariate analysis showed that only an age <75 was a significant clinical parameter on OS ( p = 0.02). Additionally, CRT was not a prognostic factor on OS, LRC, and DMFS with adjustment for age. The proportion of grade 3 or higher acute hematologic AEs was significantly greater in the CRT group than in the RT group (54% vs. 7%, p < 0.01). The proportion of grade 3 or higher non-hematologic AEs showed no differences between the CRT and RT group (36% vs. 34%). Results: