Changes in swallowing response on patients undergoing chemoradiotherapy for head and neck cancer.

Purpose: Chemoradiotherapy (CRT) for head and neck cancer (HNC) often causes dysphagia. The risk of dysphagia increases during CRT tends to become more severe after finishing CRT, and persists for a few weeks thereafter. Thus, understanding the changes in swallowing physiology during and immediately after CRT is essential. This study aimed to clarify the changes in the swallowing response during and early after CRT and identify associated factors.

Methods: This retrospective study enrolled 107 patients with HNC who underwent CRT. We measured pharyngeal delay time (PDT) and laryngeal elevation delay time (LEDT) as indicators of the timing of the swallowing response at three time points: at CRT initiation (baseline), at 40-Gy irradiation during CRT (mid-CRT) and within 2 weeks following the completion of CRT (early post-CRT) as primary outcomes; and subgroup analyses based on clinical parameters, such as tumor sites, T stage, N stage, and opioid use at 40-Gy irradiation as secondary outcomes.

Results: Both PDT and LEDT were significantly prolonged between baseline and mid-CRT (PDT: p = 0.003, LEDT: p = 0.002) and between baseline and early post-CRT (PDT, p = 0.001; LEDT, p < 0.001). N2c/N3 and opioid use at 40-Gy irradiation showed prolonged PDT and LEDT at mid-CRT and early post-CRT.

Conclusion: PDT and LEDT were prolonged at mid-CRT irradiation and further extended at early post-CRT. Additionally, N2c/N3 involvement, which typically necessitates bilateral neck irradiation fields and opioid use at mid-CRT, may constitute as risk factors for a delayed swallowing response.