Timing of radiotherapy and chemotherapy start for patients treated with definitive concurrent chemoradiation for head and neck cancer

Background The ideal timing for the initiation of chemotherapy and radiation therapy (RT) in the use of definitive chemoradiation (CRT) for patients with head and neck cancer is not well established. We sought to evaluate the impact of the timing of initiating these two modalities on clinical outcomes. Materials and methods Patients with squamous cell carcinoma of the head and neck who were treated using definitive chemoradiation from 2012 to 2018 were identified. Patients undergoing re-irradiation, post-op CRT, had recurrent or second primaries, or ECOG 3-4 were excluded. Outcomes including locoregional control (LRC), distant control (DC), progression-free survival (PFS), and overall survival (OS) were estimated and compared between subgroups of the cohort based on the timing in which chemotherapy or RT were initiated: chemotherapy first, same day start, within 24 h, or start on Monday/Tuesday/Wednesday. Results A total of 131 patients were included for analysis consisting of oropharynx (64%), larynx (22.9%), nasopharynx (6.9%), hypopharynx (3.1%), oral cavity (1.5%), and unknown primary (1.5%). Chemotherapy was administered as bolus cisplatin every 3 weeks in 40% of patients and weekly cisplatin in 60% with a median cumulative dose of 240 mg/m(2). In the multivariable analysis (MVA), starting chemotherapy before RT was associated with improved LRC (HR 0.33, 95% CI: 0.11-0.99). Three-year LRC for patients starting chemotherapy first was 90.9% compared to 78.2% in those starting RT first. In the MVA, cisplatin regimen and cumulative cisplatin dose were associated with improved OS, while no factors were significantly associated with DC or PFS. Conclusion Starting chemotherapy prior to radiation therapy improves LRC, but did not impact DC, PFS, or OS. Clinical outcomes were not different when stratifying by the other differences in the timing of initiating chemotherapy or RT.