"Swallowing of food and liquids including saliva is a complex biomechanical interaction of physiology and anatomy that occurs in four stages: oral preparatory, oral, pharyngeal, and esophageal [1, 2]."
"Dysphagia and odynophagia (painful swallowing) are common in cancer patients. Most studies on this complication are performed in patients with head and neck cancers (HNC), but swallowing disorders may also develop in patients with other malignancies."
"Non-head and neck cancers
Acute as well as chronic dysphagia may develop in any cancer patient with oropharyngeal mucositis as a result of treatment toxicity to the esophagus or secondary infection..... Dysphagia may also develop in patients with a wide variety of malignancies treated with targeted therapies."
Concluding remarks and future directions
"Most studies are performed in HNC patients, but the heterogeneous nature
of studies with respect to design, inclusion criteria,
and dysphagia assessment makes it difficult to obtain a clear insight
in the prevalence and severity of dysphagia and
aspiration after different treatment modalities. These conditions are
likely
underreported [52, 98]."