Ask the expert: what does a new literature review reveal about taste and smell alterations in people living with cancer?

• Of the tens of millions of people receiving treatment for cancer worldwide, as many as 90% may experience alterations in their sense of taste, smell, or both.^1,2 Yet despite how common they are, taste and smell alterations (TSA) are frequently considered minor or temporary side-effects of cancer treatments, and therefore overlooked in clinical care.
• The impact of TSA, however, can be far greater than recognized, as they can make it difficult for patients to eat and maintain adequate dietary intake—an important factor for quality of life and treatment outcomes.
• In this blog, lead authors of a new review paper examine the prevalence, mechanisms, and impacts of TSA in patients with cancer. They explore their findings and explain how the healthcare and nutrition industries can better support patients and improve their nutritional wellbeing.

Published in Clinical Nutrition Open Science, the new literature review explores taste and smell alterations (TSA) in patients with cancer and their impact to help identify strategies to better support patients—and ultimately improve treatment outcomes.

The review found that TSA are among the most common side effects of cancer and its treatment, with smell alterations reported in up to 60% of patients, and taste alterations impacting as many as 90%.^1,2 The authors also found that, rather than a single mechanism, TSA can be caused by several overlapping factors, meaning the nature and severity of symptoms can vary widely between patients and over the course of treatment.³

Critically, TSA are shown to negatively affect food enjoyment, appetite, and nutritional intake, contributing to weight loss, increased malnutrition risk, and reduced quality of life. Despite this, the review identified no widely accepted, evidence-based intervention for the prevention or treatment of TSA, highlighting a significant gap in supportive cancer care.³

We sat down with the paper’s lead author, Dr. Alessia Delbrück, Associate Innovation Director Medical Nutrition at dsm-firmenich, and Dr. Ruben Hack, Medical Oncologist at the Cantonal Hospital of Winterthur, Switzerland, to discuss their findings and explore how healthcare professionals, researchers, and medical nutrition formulators can address TSA to improve patients' nutritional intake, quality of life, and potentially treatment outcomes.

1. Why do you think TSA receive less attention than other treatment-related symptoms in patients with cancer?

Dr. Ruben Hack: 

First and foremost, there are practical barriers. The mechanisms underlying TSA are complex and multifactorial, making their evaluation and management equally so. Routine assessment of taste and smell function is not commonly integrated into oncology practice, and there is a lack of standardized screening methods. Additionally, there are unfortunately very little evidence-based interventions available today to address them. I think this is likely a major reason why healthcare professionals focus on other symptoms, where clearer management options are available. Further, in oncology care, clinical attention is typically focused on symptoms considered more acute or immediately impactful, such as pain, nausea, or diarrhea. TSA, by contrast, are rarely life-threatening in themselves, so they can be perceived as less urgent. But the consequences of TSA can be far from minor. That’s because TSA affect not only eating behavior and therefore nutritional intake, but also food enjoyment, social interactions, and emotional well-being. Unfortunately, these impacts are indirect and hard to quantify, which means they often go unrecognized by clinicians. Last but not least, patients themselves may not proactively report these challenges too, which compounds the problem.

2. What are the main biological factors behind TSA in cancer patients, and why does the experience vary so much between individuals?

Dr. Alessia Delbrück:

TSA can arise from both the cancer itself and its treatment, with multiple, often overlapping, contributing factors. Chemotherapy, targeted therapies, radiotherapy, surgery, and supportive medications can all affect sensory perception, often through multiple pathways acting simultaneously. Increased inflammation, altered taste receptor turnover, nutritional deficiencies such as zinc deficiency, salivary dysfunction, and oral conditions like mucositis are just some of the factors that are associated with TSA in people undergoing cancer treatment.

What’s more, differences in cancer type, treatment regimen, genetics, age, baseline sensory function, and overall health all influence the severity and nature of symptoms. As a result, one patient may experience a general reduction of taste perception, while another may find that familiar foods taste metallic, bitter, or otherwise distorted. This variability is one of the reasons TSA are so difficult to predict and manage.

3. Based on your review of the evidence, what is the biggest misconception about TSA in cancer care that healthcare professionals and researchers should address?

Dr. Alessia Delbrück:

Perhaps the biggest misconception is that TSA are a minor, short-term frustration rather than a clinically relevant symptom. In reality, TSA can greatly reduce food intake, with real impacts on nutritional status, malnutrition risk, and potentially treatment outcomes themselves. That’s not to mention the detrimental effects on mental health that come with diminished enjoyment of food and impairment of the social and cultural participation that so often comes with meals.

Recognizing the impact of TSA on people living with cancer, is the first step towards developing the research and interventions needed to effectively address them.

4. What would a more effective approach to identifying and monitoring TSA look like in real-world clinical settings?

Dr. Ruben Hack:

Simple, validated patient-reported questionnaires and more standardized assessment approaches could help clinicians identify patients experiencing TSA and facilitate more meaningful comparisons across studies. This is important because without consistent methods of assessment, it is difficult to build the evidence base needed to develop effective interventions.

Periodic monitoring is also important. TSA can evolve throughout the treatment journey, with symptoms emerging, intensifying, or changing character. Recognizing this would help adapt supportive care strategies over time.

5. How can medical nutrition solutions be developed to meet nutritional requirements while also addressing the sensory challenges of TSA?

Dr. Alessia Delbrück:

The most effective nutritional solution only works if patients are willing to consume it as required. Sometimes this can be for long periods of time. Optimizing flavor, texture, and the overall consumption experience is therefore just as important as meeting nutritional requirements, helping patients maintain adequate intake.

This means addressing sensory challenges from the outset. For example, products can be designed with modulated flavor, e.g. reduced bitterness, reduced metallic notes and other off-notes patients may be particularly sensitive to. Sweetness and flavor intensity can be adapted, depending on patients’ needs. Flavor profiles can be extended from the typically sweet flavors to savory options. Trigeminal sensations (e.g. cooling or warming) can be leveraged to enhance flavor perception. 

More personalized approaches may also be needed, given TSA vary so widely between individuals and can change over the course of the treatment. A solution that works for one patient at one stage of their therapy may not work for another, or even for the same patient a few weeks later. A one-size-fits-all approach is unlikely to be effective. Patients may benefit from having multiple flavour, texture, and format options that can be adjusted over time according to their sensory preferences and needs.

And most importantly, cancer patients themselves should be active partners in this process. Co-developing solutions with patients experiencing TSA issues first-hand helps ensure that interventions are relevant, acceptable, and effective in real-world settings.

6. As cancer treatments become more diverse, where do you see the biggest opportunities to advance TSA management and improve patient care?

Dr. Ruben Hack:

TSA are not only associated with traditional chemotherapy. Newer targeted therapies can also contribute to sensory changes, potentially through distinct biological mechanisms. Therefore, as the treatment landscape diversifies, we see new patterns of TSA emerge—making it increasingly important to understand how different therapies affect patients’ sensory experiences.

More systematic assessment and reporting of TSA in clinical trials will be key to building this understanding. Better data on prevalence, severity, and impact across treatment modalities will enable more effective and personalized management strategies, tailored to individual patients and therapies.

Advancing this work will require closer collaboration between clinicians, researchers, and the nutrition industry. Clinical evidence for effective interventions is needed to ensure that insights translate into practice. 

7. What one message would you like healthcare professionals and researchers to take away from your review?

Dr. Alessia Delbrück:

Never underestimate the impact of TSA. What may seem like a minor side effect can profoundly affect how patients eat, feel, and engage with daily life. For many people going through cancer treatment, eating is much more than a way to meet nutritional needs. It is a source of comfort, pleasure, normality, and social connection. When taste and smell are altered, that experience can be lost.

Recognizing and addressing TSA is therefore not only about improving nutrition and clinical outcomes, but about helping patients maintain quality of life, dignity, and a sense of self during one of the most difficult experiences a person can go through.