Learned food aversions, aversions which form towards foods following a pairing of their ingestion with the malaise associated with selected treatment regiments, have been implicated in the anorexia of cancer. Our previous work has served to characterization such aversions in chemotherapy patients and to suggest an approach for reducing or preventing an influence of this adverse treatment side-effect on a patient's dietary practices. The purpose of this proposed project is to confirm and extend our previous findings by a) characterizing learned food aversions in radiotherapy patients, b) assessing the role of nausea and emesis as mediators of the phenomenon and c) evaluating the efficacy of different potential blocking agents which may be used to protect foods in the patient's diet from becoming aversive. Three hundred cancer patients meeting stipulated criteria will be stratified according to the nature of their pathology and prescribed treatment as well as exposure to aversion blocking agents. Each patient will be evaluated before their first course of therapy and at certain time points over the subsequent 6 months. The acquisition of food aversions will be ascertained by a) open-ended questionnaires, b) ratings for items consumed in close temporal proximity to treatment on a FACT scale and c) a two-choice food consumption task. Patient nutritional status will be monitored via assessments of weight, serum albumin and transferrin as well as total lymphocyte count and correlated with the incidence of aversions and treatment outcome. The role of the emetic reflex in the acquisition of learned aversions will be determined by monitoring peripheral arginine vasopressin levels in patients with different post-treatment illness response who do and who do not form aversions. A better understanding of the nature and clinical implications of learned food aversions among cancer patients should enhance current management practices and may thereby exert a positive impact on the quality of life and prognosis of selected patients.