What is cancer fatigue?

Cancer fatigue or cancer tiredness is experienced by up to 95% of people who have been diagnosed with cancer. It is a complex health condition that is caused by physical, mental, emotional, behavioural, and social factors. 

Cancer-related fatigue is more than just being tired! It is defined as a persistent and often overwhelming feeling of tiredness, exhaustion, and lack of energy that is different from normal fatigue because it is not relieved by rest or sleep. Without treatment, cancer fatigue can greatly limit a person’s ability to engage in normal daily activities and lead a fulfilling life.

Who is at risk?

Currently, there are no great ways to predict who will develop more severe levels of cancer-related fatigue and who will not. However, many of the recognized risk factors for developing cancer-related fatigue are modifiable (treatable). The main cancer fatigue risk factors are:

How to know if you, your loved one, or your patient has cancer-related fatigue

Constant exhaustion is not the only sign that someone is experiencing cancer-related fatigue. The symptoms of cancer-related fatigue can be as different as the people experiencing them. However, some of the more common symptoms of cancer-related fatigue include:

• Strong and constant feelings of tiredness and exhaustion
• Decreased energy levels
• Decreased ability to carry out normal daily activities
• Decreased motivation and interest in activities
• Changes in sleep patterns
• Changes in appetite
• Decreased mental alertness, concentration and memory
• Irritability and mood changes

An unpredictable health problem

The causes, severity, timing and impact of cancer-related fatigue are different for everyone.  These factors may also change unpredictably within people over time. 

In general, cancer-related fatigue: 

1. is caused and influenced by more than one factor;
2. is more intense in people who are actively receiving or who recently completed cancer treatments; 
3. can develop, get worse, or come back again at any time following a cancer diagnosis; 
4. can last for just a couple of days or may continue for many years; and,
5. may be very troublesome (intense and long-lasting) for people living with chronic or advanced stages of cancer who are receiving long-term maintenance treatment protocols.

In fact, cancer-related fatigue can be more challenging to predict and treat compared to other health problems because there is no single cause or major contributing factor. 

What are the main treatable causes of cancer fatigue?

Many of the physical, mental, emotional, behavioural, and social factors that are known to cause and contribute to cancer-related fatigue are commonly experienced by people living with and after cancer. Fortunately, many of the main causes of cancer fatigue are treatable, including:

• Anemia: Anemia is a common side effect of cancer and its treatments that is characterized by a low red blood cell count. Cancer and anticancer therapies can cause anemia by affecting the bone marrow’s ability to produce red blood cells – reducing the body’s ability to transport oxygen and produce energy.

• Sleep disturbances: Difficulty falling and staying asleep, as well as poor sleep quality, can result in decreased energy levels, physical and mental performance, and immune function – all of which can contribute to cancer-related fatigue.

• Nutritional problems: Deficiencies in certain nutrients also contribute to cancer-related fatigue by affecting the body’s energy production and delivery systems (e.g. anemia). Poor nutrition is shown to cause decreased energy levels, physical and mental performance, and immune function – leading to fatigue.

• Emotional challenges: Depression and anxiety are common mental health conditions experienced by people living with and after cancer that contribute to cancer-related fatigue in several ways. Depression can cause feelings of sadness, hopelessness, and a loss of interest in activities that were previously enjoyed. Anxiety can cause feelings of worry, nervousness, and fear. These negative feelings often result in decreased energy levels, physical activity, and mental alertness – all of which contribute to cancer-related fatigue.

• Hormone imbalance: Hormones play a crucial role in controlling your body’s metabolism, energy levels, and physical and mental performance. Cancer and cancer treatments typically cause hormone imbalances by affecting the production and regulation of hormones in the body which negatively impact the body’s energy production and delivery systems.

• Exercise intolerance: Exercise intolerance is a common issue in people living with and after cancer that makes it more difficult for people to engage in exercise and perform physical activities that were previously routine (e.g. walking, climbing stairs, carrying groceries). Cancer and its treatments can cause exercise intolerance by impairing the body’s energy production and delivery systems as well as causing muscle weakness and wasting – which directly contribute to cancer-related fatigue.

• Immune dysfunction & Infections: Cancer and cancer treatments can directly impair the function of the immune system (e.g. damaging or decreasing the number of white blood cells), which increases inflammation and the risk of infections. When this happens, the body has to work harder (use more energy) to control the inflammation, repair the immune system, and fight infections.

• Chronic pain: Cancer and cancer treatments cause pain by damaging tissues and nerves and by increasing inflammation. The resulting pain can contribute to cancer-related fatigue by causing physical and emotional stress and by disrupting physical activity behaviour, mental alertness, and sleep.

• Medication complications: Some medications directly contribute to cancer-related fatigue by affecting the body’s energy production and delivery systems (e.g. anemia). Other medications indirectly contribute to cancer-related fatigue through their impact on sleep quality and duration as well as appetite. Other side effects include decreased alertness, energy levels, and physical and mental performance.

• Cognitive challenges: Cancer, cancer treatments, and common symptoms experienced by people living with and after cancer can interfere with people’s memory, language, word finding, multitasking, organizing and planning, taking initiative, mental calculations, and concentration. Challenges in any of these areas can be mentally exhausting and can contribute to a person’s overall fatigue. 

REFERENCES: Bower J, Nat Rev Clin Oncol, 2014; Mortimer et al., J Nat Comp Cancer Network, 2010; O’Higgins et al., Support Care Cancer, 2018; Thong et al., Curr Treat Options Oncol, 2020; Tian et al., Oncologist, 2016; Uslu and Canbolat, Sem Oncol Nursing, 2021; Wan, X. Clin J Oncol Nursing, 2008

Timing & severity of cancer-related fatigue

Cancer-related fatigue can be very unpredictable and can first develop at any time following a cancer diagnosis. It may also worsen or come back without warning in people with stable fatigue or in those who were previously affected by it. 

According to the Canadian Cancer Society, 25-30% of cancer patients experience fatigue that lasts for months or years after treatment. The duration of cancer fatigue is influenced by various factors such as a person’s cancer type and stage, the types of cancer treatments people are exposed to, the presence or development of health conditions that contribute to fatigue, and, importantly, whether or not people receive treatment for their fatigue. In some cases, fatigue may persist even after cancer treatment has ended. Bone marrow transplants, for example, can cause prolonged fatigue that lasts up to and beyond one year. 

It’s crucial to understand that cancer-related fatigue differs from the normal tiredness felt after a day’s activities, and can be a major burden that necessitates medical intervention. Studies have shown that cancer-related fatigue is more likely to get worse or come back in people who initially experience higher levels of fatigue. Therefore, even if you are experiencing some level of fatigue, getting help to prevent your fatigue from getting worse could dramatically impact your fatigue levels for years to come.

Typical patterns of cancer-related fatigue

Impact of cancer-related fatigue

Cancer-related fatigue can make it difficult for you to:

• care for yourself and loved ones
• cope with your treatments
• plan for your future
• maintain and/or return to your work, school and social life
• honour your personal, professional and community commitments
• live a life of quality, passion and purpose

The good news is, living with cancer-related fatigue DOES NOT need to be your “new normal”! 

Get the answers you need and the care you deserve

Nervous about developing cancer-related fatigue? Tired of being tired? 

Trying to address problems that you do not completely understand is a waste of your time and energy! 

As your healthcare partner, Cancer Fatigue Services provides comprehensive and convenient fatigue assessment services to ensure that you have all the information you need to make informed decisions about your health and fatigue-related care. We work for you to ensure that you receive the high-quality, efficient, and effective care you need to relieve your fatigue and restore your hope for enjoying a life not limited by it.

If you are newly diagnosed, currently receiving treatment, living with cancer, or living beyond it, we can help you maintain and retake control of your life!