title: Irradiation impairment of umami taste in patients with head and neck cancer.
abstract: BACKGROUND
  Previous studies have reported the alteration of the four basic tastes (sweet, salty, sour and bitter) in patients with head and neck cancer (HNC) during radiotherapy. However, there has been no investigation on the function of umami taste, a novel basic taste recognized recently, during head and neck irradiation.
  
  
  OBJECTIVE
  To investigate the recognition threshold of umami and the four basic tastes at different irradiation dose intervals during radiotherapy for head and neck cancer.
  
  
  METHODS
  In 30 patients with malignant neoplasm of head and neck, objective taste thresholds were examined by use of a whole-mouth method at pre-radiotherapy, irradiation doses at 15, 30, 45, and 60 Gy, respectively. Subjective taste loss and some distresses were recorded simultaneously.
  
  
  RESULTS
  Sweet, sour, salty, and bitter tastes showed temporarily and slightly increased thresholds during the treatment, but no statistical difference was found between the threshold at pre-radiotherapy and that at 15, 30, 45, and 60 Gy in any taste quality (all P > 0.05). Significantly impaired threshold of umami taste was revealed at 30 Gy (P < 0.05) and remained throughout the following treatment (at 45 and 60 Gy, both P < 0.01). Subjective taste impairment, appetite loss and satisfaction with the current state tended to deteriorate significantly during the irradiation. Mean body weight of the patients experienced a continuous loss, decreasing from an average of 60.4 kg before treatment to 57.3 kg at 60 Gy (P < 0.01). Scores of satisfaction with current state showed a significant correlation with umami taste thresholds (P = 0.035).
  
  
  CONCLUSIONS
  The clinical impairment pattern of umami taste is different from that of the other four basic tastes in HNC patients during radiotherapy. Impaired umami taste acuity plays an important role in impacting the quality of life of the patients irradiated to the head and neck.
authors.affiliation: Department of Otorhinolaryngology, Graduate School of Medical Sciences, Kyushu University, Higashi-Ku, Fukuoka 812-8582, Japan. shihaibo@qent.med.kyushu-u.ac.jp
authors.forename: Hai-Bo
authors.initials: HB
authors.lastname: Shi
authors.forename: Muneyuki
authors.initials: M
authors.lastname: Masuda
authors.forename: Toshiro
authors.initials: T
authors.lastname: Umezaki
authors.forename: Yuichiro
authors.initials: Y
authors.lastname: Kuratomi
authors.forename: Yoshihiko
authors.initials: Y
authors.lastname: Kumamoto
authors.forename: Tomoya
authors.initials: T
authors.lastname: Yamamoto
authors.forename: Sohtaro
authors.initials: S
authors.lastname: Komiyama
mesh_terms: D006258:Head and Neck Neoplasms / Q000532:radiotherapy*; D006801:Humans; D011788:Quality of Life; D011878:Radiotherapy / Q000009:adverse effects; D011879:Radiotherapy Dosage; D012684:Sensory Thresholds / Q000528:radiation effects*; D013649:Taste / Q000528:radiation effects*