Does head and neck radiation therapy increase the risk of aspiration?

From the Guidelines

Head and neck radiation therapy significantly increases the risk of aspiration, with reported rates ranging from 40% to 80% in symptomatic patients, as a result of radiation-induced damage to the muscles, nerves, and tissues involved in swallowing. Radiation treatment to the head and neck region can cause inflammation, fibrosis, and reduced saliva production, leading to dysphagia and increasing aspiration risk 1. The damage can affect critical structures like the pharyngeal constrictors, larynx, and esophageal entrance, resulting in impaired normal swallowing function.

Mechanisms of Aspiration Risk

• Radiation causes inflammation, fibrosis, and reduced saliva production, all of which impair normal swallowing function
• The damage can affect critical structures like the pharyngeal constrictors, larynx, and esophageal entrance
• Patients may experience both acute effects during treatment (inflammation, mucositis, pain) and late effects that develop months or years after radiation (fibrosis, nerve damage, tissue atrophy)

Factors Influencing Aspiration Risk

• Radiation dose: higher doses increase the risk of aspiration
• Field size: larger fields increase the risk of aspiration
• Fractionation schedule: altered fractionation schedules can increase the risk of aspiration
• Concurrent chemotherapy: chemotherapy given concurrently with radiation increases the risk of aspiration

Clinical Implications

• Patients undergoing head and neck radiation should be evaluated by speech-language pathologists before, during, and after treatment to assess swallowing function and implement appropriate swallowing exercises and compensatory strategies to reduce aspiration risk and maintain nutritional status 1
• The ability of dose-limiting treatments to reduce normal tissue damage and preserve function offers promise to avoid long-term functional deterioration
• Patients with difficulty swallowing before treatment are at higher risk for chronic dysphagia and permanent feeding tube dependency, and prolonged intervals of nothing per oral for more than 2 weeks during RT or CRT are associated with poorer swallowing outcomes 1

From the Research

Head and Neck Radiation Therapy and Aspiration Risk

• Head and neck radiation therapy has been shown to increase the risk of aspiration in patients with head and neck cancer 2, 3, 4, 5, 6
• Studies have reported a significant incidence of aspiration and aspiration pneumonia in patients treated with radiation therapy for head and neck cancer, with rates ranging from 24% to 59% 2, 3, 6
• The risk of aspiration is higher in patients who undergo neck dissection after radiation therapy 4
• Aspiration can be a silent complication, with patients not exhibiting a cough reflex or other symptoms, making it difficult to diagnose without diagnostic studies such as modified barium swallow (MBS) 2, 6
• The prevalence of aspiration is often underreported in the literature due to its silent nature, highlighting the need for routine post-therapy videofluoroscopy and swallowing therapy to reduce the risk of aspiration pneumonia 5, 6

Factors Associated with Aspiration Risk

• Severe dysphagia, tube feeding, and incomplete response to treatment are significant risk factors for aspiration pneumonia 3
• Neck dissection after radiation therapy increases the risk of aspiration as a late effect in patients with head and neck cancer 4
• Accelerated fractionation radiation therapy may increase the risk of aspiration compared to conventional fractionation 4
• Mucositis scores, prolonged tube feeding, presence of tracheostomy tube, and gemcitabine doses are not found to be related to aspiration or pneumonia risk 5

Clinical Implications

• Aspiration pneumonia can be a fatal complication of head and neck radiation therapy, with reported mortality rates ranging from 9% to 15% 3, 6
• Diagnostic studies such as MBS should be included in future prospective head and neck cancer studies to assess the prevalence of aspiration and guide rehabilitation efforts 2, 6
• Swallowing therapy and training in safe swallowing strategies may help reduce the risk of aspiration pneumonia in patients with head and neck cancer 5