Subjective and objective taste and smell changes in cancer.

CONTEXT: Malnutrition is highly prevalent in cancer patients and an important predictor of morbidity, mortality, treatment response, and toxicity. Taste and smell changes (TSCs) are common and may contribute to malnutrition. Research has previously focused on patients receiving chemotherapy (CT) or head and neck radiotherapy (RT). However, TSCs may occur pre-treatment, with other treatment modalities, and in cancer survivors. This review evaluates objective and subjective assessment of taste and smell, discusses the prevalence of TSCs in cancer, and reviews the clinical sequelae of TSCs in cancer patients. OBJECTIVES: To critically evaluate objective and subjective assessment of TSCs, and the prevalence and clinical sequelae of TSCs in cancer. METHODS: A literature search was conducted using PubMed, CINAHL and Embase for English-language articles published January 2009-June 2016. Search terms included combinations of the following: chemosensory, taste, smell, cancer, chemotherapy, radiotherapy, hormone therapy, immunotherapy, survivors. Reference lists of articles retrieved were also reviewed. RESULTS: Variation in objective and subjective assessment methodologies has resulted in difficulties interpreting the literature. TSC prevalence varies depending on stage of disease and treatment regimens, from 16% to 70% and 50% to 70% during CT and RT, respectively. TSCs in patients who are treatment-naïve, receiving hormone or immunotherapy treatment, post-treatment and cancer survivors have not been adequately studied. TSCs are associated with impaired nutritional status. The relationship between cancer-associated symptoms and nutritional status is not clearly defined. CONCLUSION: There is no gold standard assessment tool for TSCs. Heterogeneity in study methods hinders conclusive identification of the most appropriate way to measure TSCs. Subjective measures may reflect the patient experience and more reliably predict changes in dietary behaviour. Evaluation of TSCs should form part of all nutritional assessments in cancer patients. The true prevalence and severity of TSCs at all stages of cancer could then be established.

Subjective taste and smell changes in treatment-naive people with solid tumours.

PURPOSE: Taste and smell changes (TSCs) are common in head and neck (H&N) cancer and during and after chemotherapy (CT) and radiotherapy (RT). It is an area that has been under-investigated, particularly in the treatment-naive, but can negatively impact nutritional status. This study examined the prevalence, severity and characteristics of TSCs in people with non-H&N solid tumours, before CT and RT, and their relationship with co-occurring symptoms. METHODS: A prospective, observational study was conducted. Forty consecutive pre-treatment cancer patients, referred to radiation oncology outpatients over 6 weeks, were recruited. Data on TSCs, symptoms and nutritional status were obtained using the 'Taste and Smell Survey' and the 'abridged Patient-Generated Subjective Global Assessment' (abPG-SGA). BMI was measured. SPSS® was used for statistical analysis. Two-sided P values <0.05 were considered statistically significant. RESULTS: Most patients were newly diagnosed (n = 28; 70 %). Nineteen (48 %) reported TSCs; nine noted a stronger sweet and seven a stronger salt taste. Of these, four reported a stronger and four a weaker smell sensation. Those at nutritional risk reported more TSCs (n = 13/20). TSCs were significantly associated with dry mouth (P < 0.01), early satiety (P < 0.05) and fatigue (P < 0.05). CONCLUSIONS: TSCs preceded CT or RT in almost half of treatment-naive patients with solid tumours, notably stronger sweet and salt tastes. Half of the study group were at nutritional risk; the majority of these reported TSCs. TSCs were significantly associated with other symptoms. Future research and clinical guidelines, with a common terminology for assessment, diagnosis and management of cancer TSCs, are needed.