Sensory alterations in patients with cancer

Taste and smell are essential senses that work together, allowing us to perceive flavour.¹Spotten LE, Corish CA, Lorton CM, et al. Ann Oncol. Published on 2017;28(5):969-984 The sense of taste helps to regulate food intake by allowing us to decide quickly whether to accept or reject a food.²Murtaza B, Hichami A, Khan AS, et al. Front Physiol. Published on 2017;8:134 Taste perception activates neuronal pathways, aiding the digestion, absorption and storage of nutrients.³Murtaza B, Hichami A, Khan AS, et al. Front Physiol. Published on 2017;8:134 Taste also provides hedonic pleasure from eating.⁴Murtaza B, Hichami A, Khan AS, et al. Front Physiol. Published on 2017;8:134

Disturbances in taste perception, known as dysgeusia, can occur for many different reasons, including disease and medication.⁵Spotten LE, Corish CA, Lorton CM, et al. Ann Oncol. Published on 2017;28(5):969-984 Altered taste perception is especially important in cancer as it can lead to reduced food intake, weight loss, and malnutrition  – all of which are linked to poor disease outcomes and lower quality of life.⁶Arends J, Bachmann P, Baracos V, et al. Clin Nutr. Published on 2017;36(1):11-48

How common are sensory changes in cancer?

Taste changes affect up to 70% of patients with cancer.⁷Spotten LE, Corish CA, Lorton CM, et al. Ann Oncol. Published on 2017;28(5):969-984   This compares with a reported prevalence of 20% in the general population.⁸Vennemann MM, Hummel T, Berger K, J Neurol. Published on 2008; 255(8): 1121–1126 Taste changes have been reported before, during, and after treatment for cancer; in many different tumour types; and in patients receiving either chemotherapy or radiotherapy.⁹Spotten LE, Corish CA, Lorton CM, et al. Ann Oncol. Published on 2017;28(5):969-984  

Despite their near-ubiquity, taste changes in cancer patients are not always recognised by clinicians and researchers, leaving important questions unanswered.¹⁰Murtaza B, Hichami A, Khan AS, et al. Front Physiol. Published on 2017;8:134 For instance, the physiological mechanisms underlying taste alterations have not been fully elucidated and there is no “gold standard” assessment tool.¹¹Spotten LE, Corish CA, Lorton CM, et al. Ann Oncol. Published on 2017;28(5):969-984

What type of sensory changes occur in cancer?

Sensory changes in patients with cancer occur as a consequence of the disease or its treatment. They manifest in various ways:¹²Brisbois TD, de Kock IH, Watanabe SM del. et al. J Pain Symptom Manage. Published on 2011;41(4):673-83 /

• Taste aversion to some flavours
• Changes in mouth feeling
• Changes in flavour thresholds
• Changes in flavour preference
• Bad tastes in the mouth
• Variation in smell

Disturbances of all taste modalities have been reported in cancer patients. Hyper- and hypogeusia for salt and sweet tastes are widespread, while changes to bitter and sour have been reported.¹³Spotten LE, Corish CA, Lorton CM, et al. Ann Oncol. Published on 2017;28(5):969-984

Metallic taste is also common; in a recent study, 16% of cancer patients receiving chemotherapy, radiotherapy, or targeted therapy reported a metallic taste. These individuals also tended to experience hypergeusia for sour and bitter tastes.¹⁴IJpma I, Timmermans ER, Renken RJ, et al. Nutr Cancer. Published on 2017;69(1):140-145 / In another study, breast cancer patients undergoing chemotherapy showed an altered preference for certain macronutrients rather than specific tastes.¹⁵de Vries YC, Winkels RM, van den Berg MMGA, et al. Food Qual Prefer. Published on 2018; 63: 135–143

Taste and smell alterations are typically noticed by patients shortly after treatment begins and may persist for 6–12 months after treatment ends.¹⁶Spotten LE, Corish CA, Lorton CM, et al. Ann Oncol. Published on 2017;28(5):969-984 Occasionally, cancer-associated dysgeusia is permanent.¹⁷Ruo Redda MG and Allis S, Cancer Treat Rev. Published on 2006;32:541–547