For some, fatigue can become persistent and disrupt their daily life. When fatigue becomes frequent, it is natural to be concerned about what may be causing it.
Cancer is one of the first things many people think of when experiencing fatigue. They may wonder if cancer is the culprit.
This article reviews what cancer fatigue is, what causes it, how it’s diagnosed, and when to see a healthcare provider.
What Is Cancer Fatigue
Defining the type of fatigue that could be a cancer symptom or treatment is essential. Cancer fatigue isn’t ordinary tiredness. It’s not usually the kind of sleepiness you can push through by getting a good night or with a cup of coffee.
People describe this type of fatigue as “whole-body tiredness.” It’s also something that often disrupts life. People become frustrated at their inability to participate in everyday activities and find their tiredness impacts their jobs and relationships.
Causes of Cancer Fatigue
Anemia
Anemia is when your red blood cell (RBC) count is lower than normal or there is a problem with the hemoglobin. Hemoglobin is the part of the red blood cell that carries oxygen to your tissues and organs. Not having enough RBCs or hemoglobin decreases oxygenation, making you feel weak and tired.
There are many causes of anemia related to cancer. Some include:
Decreased production of blood cells: Both leukemia and lymphoma are cancers that affect the bone marrow and disrupt the normal production of blood cells. Blood loss: Some cancers, such as colorectal or stomach cancer, and surgeries can cause blood loss. Nutritional deficiencies: Not eating a healthy diet can lead to iron-deficiency anemia. Chemotherapy: Chemotherapy attacks both healthy and nonhealthy cells. If it attacks the bone marrow, which produces blood cells, it can cause anemia. Kidney damage: Some cancers or treatments can cause kidney damage, making the body less erythropoietin (EPO). EPO is a hormone that tells your blood marrow to make red blood cells.
Inflammation and Immune System
The tumor, surgery, cancer treatment, or activation of cytokines in your immune system can cause inflammation. This can lead to pain, infection, insomnia, lethargy, mood changes, and brain fog. Dealing with pain or any of these other symptoms or side effects can all contribute to fatigue.
Cancer Treatment
Cancer treatments such as chemotherapy, radiation therapy, hormone therapy, and surgery (and their side effects) can all contribute to tiredness for the following reasons:
Chemotherapy and radiation: These can cause fatigue because the body is working hard to repair the damage caused by the treatment. Both treatments can also cause malnutrition due to nausea, vomiting, loss of appetite, mouth sores, or taste changes. Medications: Medications used for cancer treatment, including those that treat pain and nausea, can cause sleepiness. Surgery: Fatigue from surgery can come from tissue damage and repair, lack of movement after surgery, or anesthesia (medications used to put you to sleep during surgery)
Hormones
Certain cancers or tumors can affect testosterone, estrogen, progesterone, thyroid, and adrenal hormones. Imbalanced hormones affect how the body regulates energy.
Some cancers feed off hormones. These typically require hormone therapy which can also cause fatigue.
Stress, Mental, and Emotional Changes
Having cancer can cause stress, sleeping problems, moodiness, and depression. Stress by itself can cause emotional, mental, and physical fatigue.
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Both cancer itself and stress can cause dysregulation of cortisol. Increased levels of cortisol put your body in a high-alert state. This burns a lot of energy and can lead to mental and emotional changes and sleeping problems which all lead to fatigue.
Tumor Growth
When tumors develop, they aggressively compete for nourishment with normal cells. It can also disrupt or change your metabolism, which drains your energy.
Low Oxygen
If cancer causes anemia or shortness of breath it can lead to hypoxia which means low levels of oxygen in your blood. This decrease in oxygen leads to tiredness and low energy.
Most pituitary adenomas (tumors) are non-cancerous. If the tumor damages the pituitary gland, it can disrupt the endocrine or hormone system. Some also release extra hormones into the body, causing health conditions that lead to fatigue.
Hypoxia can be an even more significant issue when someone already has a chronic condition such as cardiac or lung problems.
Diagnosis
When your chief complaint is fatigue, cancer isn’t likely to be the first thing on your healthcare provider’s mind. Fatigue is related to many other conditions, and your healthcare provider will want to rule out the most common causes first.
This will be accomplished through a physical and routine blood work. Your healthcare provider will likely order a few different blood tests to check your thyroid function.
During your visit, your healthcare provider may ask several questions about your quality of life and what factors may contribute to your fatigue. Possible questions include:
How many hours do you work? Are you stressed at work? Have you had any major life changes, such as marriage, birth, or death? How often do you exercise? Do you sleep well? How much sleep do you get? How is your diet? Do you have a family history of thyroid disease?
When to See a Healthcare Provider
Sometimes asking for help or taking good care of yourself can help you overcome fatigue. If you are still fatigued after eating well, resting, getting mild exercise, managing stress, and getting plenty of hydration, it’s best to talk with your healthcare provider.
Call your healthcare provider if you have the following symptoms:
Fatigue not relieved by self-careFatigue that affects your daily life, job, or relationshipsMemory problems, confusion, or brain fogFatigue so severe that you can’t get out of bedSevere painOngoing depressionIncreased shortness of breathSevere nausea, vomiting, diarrhea, or loss of appetiteTrouble sleeping
Summary
Cancer fatigue differs from tiredness that resolves with rest or a cup of coffee. This type of fatigue often interrupts daily life, jobs, and relationships.
Cancer fatigue can be caused by many things, including anemia, treatment, nutritional deficiencies, inflammation, hormones, low oxygen, and the tumor itself.
If you have fatigue, your healthcare provider will most likely perform a history and physical as well as run blood tests to look for the cause.
A Word From Verywell
If you’re living with cancer, you already know how cancer fatigue is different from other types of fatigue. Even though it’s common and even expected, talk to your healthcare provider if you are experiencing fatigue.
There are several causes of fatigue with cancer that don’t have an easy solution, but there are also many treatable causes of fatigue.
