Patients receiving chemotherapy may experience unpleasant taste secondary to diffusion of drug into the oral cavity. In addition, chemotherapy patients often describe dysgeusia in the early weeks after cessation of cytotoxic therapy. This symptom in general is reversible, and taste sensation returns to normal in the ensuing months.
By comparison, however, a total fractionated radiation dose higher than 3,000 Gy reduces acuity of sweet, sour, bitter, and salt tastes. Damage to the microvilli and outer surface of the taste cells has been proposed as the principal mechanism for loss of the sense of taste. In many cases, taste acuity returns in 2 to 3 months after cessation of radiation. However, many other patients develop permanent hypogeusia. Zinc supplementation (zinc sulfate 220 mg 2 times a day) has been reported to be useful in some patients; the overall benefit of this treatment remains unclear.;[Level of evidence: I]
Patients with head and neck cancer are at high risk for nutritional problems. Contributing to malnutrition are the following:
- The malignancy itself.
- Poor nutrition before diagnosis.
- Complications of surgery, radiation therapy, and chemotherapy.
In cancer patients, loss of appetite can also occur secondary to mucositis, xerostomia, taste loss, dysphagia, nausea, and vomiting. Quality of life is compromised as eating becomes more problematic. Oral pain with eating may lead to selection of foods that do not aggravate the oral tissues, often at the expense of adequate nutrition. Nutritional deficiencies can be minimized by modifying the texture and consistency of the diet and by adding more frequent meals and snacks to increase calories and protein. Ongoing nutrition assessment and counseling with a registered dietitian should be part of the patient's treatment plan.
Many patients who receive radiation therapy alone are able to tolerate soft foods; however, as treatment progresses, most patients must transition to liquid diets using high-calorie, high-protein liquid nutritional supplements, and some may require enteral feeding tubes to meet their nutritional needs. Almost all patients receiving concurrent chemotherapy and radiation therapy will become fully dependent on enteral nutritional support within 3 to 4 weeks of therapy. Numerous studies have demonstrated the benefit of enteral feedings initiated at the onset of treatment, before significant weight loss has occurred.[22,23]