No Silver Bullet for Radiotherapy-Associated Oral Mucositis or Lock Jaw in Head and Neck Cancer

Head and neck cancers and their treatment can cause painful and functionally significant acute and long-term oropharyngeal impairments, including oral mucositis and impaired tongue function, swallowing and jaw opening (trismus, or “lock jaw”).^1,2 Acute radiation mucositis involves scarring of the mucosal lining of the mouth, throat, and gastrointestinal tract. Radiation-induced trismus (RIT) is a late side effect of treatment that results from scarring and contraction of jaw muscles, resulting in a patients’ limited ability to open their mouths; onset typically occurs between 9 and 12 months after radiotherapy is completed and over time, both musculature and mandibular joints degenerate.²

Unfortunately, researchers have yet to identify a definitive preventive strategy or cure for either condition. Treatment remains largely palliative, centering around pain management and avoiding malnutrition.

Oral mucositis (OM) is common in patients undergoing systemic chemotherapy, affecting up to 40% of patients, and is ubiquitous in patients undergoing head and neck external-beam radiotherapy.³ OM involves progressive and increasingly painful damage to the oral cavity, pharyngeal, nasopharyngeal, laryngeal, salivary gland and/or hypopharyngeal tissues.¹ Worsening mucosal inflammation and, frequently, ulceration, often begin to appear after the first 10 Gy (1 to 2 weeks, depending on fractionation schedule) of external-beam radiotherapy.¹ Tongue, palate and gum ulcerations can proliferate and merge by the time a cumulative radiation dose of 30 Gy has been delivered to oropharyngeal target volumes (typically, week 3 of radiotherapy).¹ Both OM and RIT represent management challenges and appear to be related to one-another; acute OM severity is believed to be associated with the risk of RIT.²

Both RIT and OM are progressive and can degrade a patients’ and survivors’ nutritional status and quality of life. OM is a dose-limiting toxicity of both chemotherapy and radiotherapy and can lead to dose reductions and treatment interruptions, which in turn can affect treatment efficacy.¹ Symptoms include pain, dehydration, anorexia and weight loss, dysphagia, and infection risk.¹ Patients with RIT experience difficulty eating, drinking, speaking, and maintaining oral hygiene (eg, tooth brushing), which can lead to malnutrition and social isolation.² In contrast to RIT, which is a late adverse event for many patients undergoing head and neck radiotherapy, OM can sometimes begin to heal up to 4 weeks after radiotherapy is completed.¹

Because of the treatment challenges of OM and RIT, much research effort has focused on identifying effective strategies for preventing these conditions and the palliative management of symptoms (for example, morphine-based analgesia).^1,3

Not surprisingly, the most effective prevention strategy for OM involves minimizing the nontarget, healthy oral tissues that are included in high-dose radiation fields.¹

Oral hygiene may also be important.^1,3 The Multinational Association of Supportive Care in Cancer and International Society of Oral Oncology (MASCC/ISOO) have promulgated clinical guidelines for preventing and managing OM that suggested, based on limited available evidence, flossing and tooth brushing with soft-bristled toothbrushes, and mouth rinsing with saline or sodium bicarbonate washes.^1,3 In clinical practice, patients are usually advised to undergo dental corrections ahead of radiotherapy and to observe vigilant oral hygiene practices.¹