Volumetric Changes After CRT for Head and Neck Tumors May Influence Posttreatment Dysphagia

by Amy E. Hamaker •

What are the volumetric changes in pharyngeal structures in patients with head and neck squamous cell carcinoma (HNSCC) treated with curative chemoradiation therapy (CRT)?

Bottom Line: Volumetric changes following CRT may play a role in post-treatment dysphagia through physiologic function loss from posterior pharynx tissue thickening combined with reduced pharyngeal constriction capacity, and base of tongue atrophy secondary to radiation effects.

Background: HNSCC has a current incidence rate of 13/100,000. These tumors are highly radiosensitive; treatment with concurrent chemoradiation is the main modality. Radiation-induced fibrosis and dysphagia are major side effects of CRT treatment and lead to weight loss, pneumonia, social isolation, and early death.

Study design: Case series measuring the pre- and one-year post-treatment volumes of the base of tongue (BOT), parapharyngeal spaces (PPS), posterior pharyngeal constrictors (PCs), and retropharyngeal space (RPS) in patients undergoing CRT for HNSCC (n=49) or esophageal carcinoma (EC; n=11) between January 1, 2012, and December 31, 2015.

Setting: Tom Baker Cancer Centre, Calgary, Alberta, Canada.

Synopsis: Both HNSCC and EC groups lost weight following treatment. Within the HNSCC cohort, 31 tumors were classified as T1 or T2, with four primary unknown tumors. The majority of HNSCC patients had a primary tumor site in the oropharynx, and had p16-positive tumors. Twenty-two primary tumors were located in the tonsil and six were in the BOT. In the HNSCC cohort, PCs volume increased 1.55 cm3, RPS volume increased 1.22 cm3, and BOT volume decreased 2.29 cm3. The EC cohort showed no significant volumetric changes for any anatomic space, with combined PCs and RPS volume changes statistically less than the HNSCC cohort. There were no apparent PPS volumetric changes, indicating tissues surrounding the pharynx have different radiosensitivity and respond to RT to different degrees. Limitations included the possibility of the presence of a synchronous tumor or a primary unknown tumor at BOT that artificially increased volume reduction, the inability to conclude that volumetric changes are associated with functional swallowing impairments, the study’s retrospective nature, a small EC cohort, and lack of data beyond the one-year period.

Citation: Hinther A, Samson N, Lau H, et al. Volumetric changes in pharyngeal structures following head and neck cancer chemoradiation therapy. Laryngoscope. 2020;130:597-602.