Evaluation of swallowing function with clinical and dosimetric parameters in head and neck cancer patients receiving radio (chemo)therapy

This study aimed to evaluate the relationship between late dysphagia and dosimetric–clinical parameters in patients receiving radiotherapy for head and neck cancer (HNC).

Twenty-six HNC patients treated with three-dimensional conformal radiotherapy were evaluated. A total dose of 66–70 Gy in 33–35 fractions was administered for curative purposes. Six swallowing organs at risk were contoured for each patient: the superior, middle and inferior pharyngeal constrictor muscles (SPCM, MPCM and IPCM); the cervical oesophagus (CE); the base of tongue (BOT); and the larynx. The mean dose in Gray [Dmean(Gy)], maximum dose in Gray [Dmax(Gy)] and percentages of organ volumes receiving ≥ 50 Gy, ≥ 60 Gy and ≥ 70 Gy [V50 (%), V60 (%) and V70 (%), respectively] were calculated from the dose–volume histograms for each structure. Dysphagia was evaluated using video laryngoscopy, the European Organization for Research and Treatment of Cancer quality of life module for HNC and the Leipzig scale.

Dmean, V60 and V70 for the BOT; Dmean and V60 for the SPCM; Dmean, Dmax, V60 and V70 for the IPCM; Dmean, Dmax, V60 and V70 for the larynx; and Dmean, Dmax, V50 and V70 for the CE were correlated with the presence of pharyngeal secretion. Only V50 for the CE was correlated with abnormal glottic closure. Dmean, Dmax, V60 and V70 for the BOT and the SPCM were correlated with liquid swallowing problems. Dmax for the MPCM; Dmean, Dmax, V60 and V70 for the IPCM; and Dmax, V60 and V70 for the CE were correlated with the Leipzig score.

The dose–volume parameters of swallowing organs were found to be associated with different rates of late dysphagia in HNC patients receiving radiotherapy. The identification of dosimetric parameters that predict late dysphagia is not adequate yet. Well-designed multi-institutional studies are necessary to clarify the dose–volume constraints.