Taste perception occurs via receptor cells in approximately 5,000 taste buds located in the mouth and the digestive tract.1 The basic taste modalities are sweet, sour, salty, bitter and umami, and possibly fat and metallic.2
Sensory changes may arise as part of the complex pathophysiology of cancer. Potential mechanisms include systemic inflammation; modification of the gut microbiota; mechanical obstruction of chemoreceptor sites; tumour interference with neural transmission; and metabolic changes.1,2
Taste and smell changes can also occur as a side effect of cancer treatment. Radiotherapy and chemotherapy target rapidly dividing cells, such as taste and smell receptors (and their progenitor/stem cells), thereby causing cytotoxic damage. These therapies may also disrupt the production of saliva and mucous, which can affect taste indirectly by causing dry mouth and oral mucositis.1,2
Why do sensory changes matter?
Fundamentally, sensory changes matter because they impact on the hedonic experience of eating and drinking. Cancer patients experiencing taste alterations report reduced enjoyment of food, which can have significant dietary, social and emotional consequence s.3
In a study of patients undergoing chemotherapy, changes in taste and smell ranked among the five most troublesome side effects.4 Cancer patients with taste or smell alterations have a significantly worse quality of life than their counterparts with normal taste.4,5 Testimony from patients illustrate how devastating the changes can be: “I stay at home because smells make me nauseous”; “I do not enjoy eating or going to restaurants”; “I’m embarrassed because food causes unpredictable gagging or vomiting”.4
Sensory changes have a range of dietary and nutritional consequences. These include food aversion and a narrowing of food diversity;6 a 20–25% reduction in daily caloric intake;4 and weight loss.4 In a study of patients with advanced cancer undergoing chemotherapy, the average 6-month weight loss increased proportionally to the severity of chemosensory alterations. Weight loss rose from 4.3% in patients without taste or smell alterations to 5.5%, 9.0%, and 12.3% in patients who were mildly, moderately, and severely affected, respectively.4
Food aversion and weight loss are particular concerns in patients with cancer, since weight loss, malnutrition and cachexia are predictors of poor clinical outcomes.7 Patients with weight loss or cancer cachexia have a reduced tolerance to therapy, impaired quality of life, and reduced survival.8 Click here to learn more.
How can these sequelae be minimised?
In view of these negative consequences, it is critically important for clinicians to recognise the signs of malnutrition. Screening for sensory alterations is a key component of addressing the underlying causes of malnutrition in order to minimise weight loss and the risk of malnutrition and cachexia. Patients with taste changes may benefit from education and counselling. Sensory alterations influence the palatability of oral nutritional supplements, which are commonly prescribed for malnourished cancer patients.9
How is Danone Nutricia Research addressing this important issue?
Danone Nutricia Research believes that chemosensory alterations are an important and under-recognised topic in oncology . We are expanding the evidence base through our engagement in a range of ongoing sensory and behavioural studies.
“Understanding how different patients experience taste and flavour means we are better able to support their needs. Greater palatability translates into better compliance, delivers nutritional benefits, and potentially improves outcomes for patients,” says Irene Fernandez, AMN Sensory and Behaviour Science Leader, Danone Nutricia Research.
Danone Nutricia Research presented new data to facilitate greater understanding of taste changes in cancer at the ESMO 2018 Congress in Munich, Germany, 19–23 October. Click here to learn more.