People are not able to smell cancer, but dogs may be able to detect cancer from samples. People may experience changes in smell with particular cancer treatments.
This article looks at whether cancer smells and possible body odors that may signal cancers that dogs can detect. It also explores whether cancer treatments smell, if treatments cause changes in smell, the duration of these changes, and how to manage them.
Anecdotal evidence suggests that cancer does not have a scent that a human nose can detect.
Although people are not able to smell cancer, it does leave disease biomarkers or odor signatures in a person’s body and their secretions. Cancer cells do produce and release odors which doctors refer to as volatile organic compounds (VOCs).
Research from 2016 suggests that dogs may be able to detect many types of cancers in humans from the VOCs released from a person. However, people cannot detect VOCs themselves.
According to various research studies, dogs have detected the following types of cancers based on their smell:
- Melanoma: An
older case reportdemonstrated how a dog licked persistently at a lesion behind a 75-year-old male’s ear. When doctors performed tests, they confirmed a diagnosis of malignant melanoma.
- Colorectal cancer: Evidence from a 2010 study in Japan found that dogs detected colorectal cancer from people’s breath and watery stool.
- Lung cancer: A
2017 studydemonstrated that a trained dog was able to accurately identify lung cancer by distinguishing between the breaths of people. Similarly, research from 2020showed that trained dogs detected lung cancer through smelling urine samples.
- Ovarian and prostate cancer: Two research studies have also shown dogs
can detectovarian cancer from blood samples and sniff a person’s urinefor prostate cancer.
- Breast cancer: More recent
research from 2021showed that a dog detected breast cancer in urine samples of 200 people.
Research still needs to further explore this area with larger samples of dogs and humans, but the current evidence does hold promise for future detection of cancer.
In addition, certain kinds of tumors in the head and neck area
Since taste, smell, and touch work together to enable a person to experience and enjoy food, there is a risk that a change in senses may contribute to reduced appetite and weight loss. In turn, this may lead to malnutrition, which may result in the increase of side effects from cancer treatment and loss of muscle strength.
How long do changes last?
Most changes to the sense of taste and smell resolve over time and are
Anecdotal evidence suggests some chemotherapy drugs have an odor. However, it is hard to determine if the smell occurs due to changes in a person’s sensitivity to certain scents or their overall change in sense of smell.
Cancer may affect a person’s senses, causing changes before treatment begins, but the treatment itself may also affect the senses.
Chemotherapy, immunotherapy, radiation therapy, and surgery can reduce the amount of saliva the body produces. This can cause a dry mouth which further affects the sense of taste. Having a dry mouth over a long period of time may also result in mouth infections or tooth decay, which can cause further problems with taste, smell, or feeling.
In addition, the hospital or clinic setting where a person receives their treatment may also affect how a person feels when they are eating, so food may taste differently based on the environment.
How long do changes last?
Changes to taste and smell
When senses return also depends on the type of treatment and where the cancer is.
For example, people who have radiation therapy to the head or neck area may continue to experience problems as their bodies may no longer be able to create enough saliva.
If a person has chemotherapy, they might notice that senses change during the course of a single treatment cycle but then may gradually improve.
A doctor will be able to inform a person whether their senses will change and when they are likely to return.
There are many ways to manage changes to taste, smell and touch:
- It is helpful for a person to keep a record of specific changes to help doctors understand the causes and suggest possible ways to manage the side effects, such as:
- the time of day they notice the change
- how far from the start or end of their treatment cycle
- what food and drink were being consumed
- People can experiment with different foods and drinks to try newer tastes and smells.
- Experts suggest keeping the mouth clean and fresh after each meal may help with their senses.
Additional ways to manage smell changes include:
- avoiding favorite foods just before or after treatment to reduce the risk of a negative association with treatment
- asking family or friends to prepare nutritious meals or asking for guidance from a nutritionist
- rinsing away any bad tastes in the mouth as this may affect what a person smells
Further guidance from the
People cannot smell cancer, but research has shown that dogs may be able to detect certain types of cancers from urine, blood, breath, and stool samples. This is promising evidence for future detection of cancer.
Cancer may change a person’s sense of taste and smell, particularly if they have nasal cancer. These senses usually return after a short time but may be permanent in other cases depending on the specific location and treatment for the cancer.
Cancer treatments may have a certain smell, but research has not yet determined whether people have more sensitivity to smells rather than having a unique scent.
Cancer treatments may also cause taste and smell disorders. These usually disappear after treatment stops, but it may differ between people. A person can speak with a medical professional for advice.
Experts suggest the best way to manage changes to sense is to keep track of when they occur and with what foods, try consuming different meals and flavors to better understand changes, and avoid certain foods directly after treatments or side effects to avoid negative associations between them.