Adequate management of acute treatment-related toxicities is pivotal to reducing discomfort and avoiding interruption in radiotherapy. Early responding tissues to radiation include the skin, mucous membranes, and salivary glands.
In the skin, ionizing radiation primarily affects the basal proliferating layer. At lower levels of exposure, erythema and hyperpigmentation result. Dry desquamation, with xerosis and hyperkeratosis, is seen as the accumulated dose increases. At higher doses, the basal layer is no longer able to repopulate, resulting in wet desquamation and ulceration. Small areas of wet desquamation need cleaning to prevent secondary infection, with larger areas requiring hydrogel dressings and thorough wound care.
Like the skin, mucous membranes consist of rapidly proliferating cells that show dose-dependent acute toxicity. The buccal mucosa, soft palate, tonsillar pillars, and pharyngeal walls are especially prone to developing acute mucositis. With increasing radiation dose, areas of mucositis often become confluent. At doses over 7000 cGy, soft tissue or laryngeal necrosis may occur. Treatment of acute mucositis is mainly symptomatic, and includes pain management and oral irrigation with a baking soda/salt solution.
The salivary glands are relatively radiosensitive, with the threshold mean dose of radiation causing irreversible xerostomia thought to be approximately 2000–2500 cGy. Xerostomia often requires significant adaptation in lifestyle and eating habits, and can significantly impair quality of life. The availability of IMRT has opened up the possibility for parotid sparing in selected patients.
The physiologic mechanisms underlying late toxicities in most tissues have yet to be fully elucidated. Nevertheless, a combination of fibrosis, vascular endothelial damage, and muscle atrophy are though to be at work in many instances.
Chronic dysphagia is a frequently encountered issue, especially in patients treated with high-dose chemoradiotherapy. Oral, pharyngeal, and/or esophageal strictures may develop, requiring dilatation. Clinical swallowing evaluation with modified barium swallow and/or video fluoroscopy may help identify patients at risk for silent aspiration.
Trismus occurs secondary to fibrosis of the muscles of mastication, and in some unfortunate cases, due to tumor recurrence/persistence. Treatment includes regular daily jaw exercises and physical therapy.
Chronic xerostomia is a frequent late complication of radiotherapy treatment. Reduction in salivary output predisposes patients to developing caries, and excellent oral hygiene is required to prevent dental deterioration. Patients require routine fluoride prophylaxis and frequent dental evaluation. Moreover, patients receiving radiotherapy are at risk for the development of osteoradionecrosis, and any mandibular or dental pain should prompt thorough examination, including radiologic evaluation.
Ang KK et al. Randomized trial addressing risk features and time factors of surgery plus radiotherapy in advanced head-and-neck cancer. Int J Radiat Oncol Biol Phys. 2001;51:571–578.
Bernier J et al. Postoperative irradiation with or without concomitant chemotherapy for locally advanced head and neck cancer. N Engl J Med. 2004;350:1945–1952.
Cooper JS et al. Postoperative concurrent radiotherapy and chemotherapy for high-risk squamous-cell carcinoma of the head and neck. N Engl J Med. 2004;350:1937–1944.
Fu KK et al. A radiation therapy oncology group (RTOG) phase III randomized study to compare hyperfractionation and two variants of accelerated fractionation to standard fractionation radiotherapy for head and neck squamous cell carcinomas: first report of RTOG 9003. Int J Radiat Oncol Biol Phys. 2000;48:7–16.
Pignon JP et al. Meta-analysis of chemotherapy in head and neck cancer (MACH-NC): an update on 93 randomised trials and 17,346 patients. Radiother Oncol. 2009; 92:4–14.