Prospective assessment of gustatory function after radiotherapy for head and neck cancers

Background Taste disorders are major causes of morbidity in patients undergoing head and neck irradiation. We quantitatively assessed the gustatory function of patients with head and neck cancers who underwent radiotherapy using recently developed standardised tools for measuring taste. Methods Twenty patients undergoing head and neck irradiation responded to a specific questionnaire and were assessed by olfactory and gustatory function tests. To assess changes over time, testing was performed before, immediately after, and at 2- and 4-week intervals following the start of radiotherapy. Concurrently, patients were evaluated for xerostomia from radiotherapy. Results A decrease in the taste recognition threshold was observed in the second week after the beginning of radiotherapy. The taste detection threshold improved within the 14th-18th week. Most affected patients demonstrated that their gustatory function primarily decreased independent of the olfactory function. Disturbances in taste were exponentially worsened beyond an accumulated dose of 30 Gy and involved all tastants. According to a multivariate analysis, radiation-induced taste impairment was not influenced by the degree of xerostomia. However, there was an association between the dose of irradiation and the severity of taste disturbance. Conclusions In this preliminary study, we found that the taste function was worse 2 weeks after the start of radiotherapy and returned to pretreatment levels within 4.5 months. Taste disturbances were exponentially worse beyond an accumulated dose of 20 Gy. Taste dysfunction after radiotherapy was not influenced by the degree of xerostomia, whereas only the dose of irradiation was associated with the severity of taste dysfunction.