Does Breast Cancer Cause Fatigue? What You Need to Know

Breast cancer can make a person feel tired and exhausted. This may occur as a symptom of the cancer itself or as a side effect of cancer treatments such as hormone therapy, chemotherapy, and radiation therapy.

Fatigue Affects 80–100% of Cancer Patients

Exhaustion is common among people with cancer, including breast cancer. According to the American Cancer Society, 80–100% of cancer patients develop fatigue. Exhaustion includes weakness, tiredness, or low energy. Fatigue associated with various cancers can affect daily activities and reduce a person's quality of life. Fortunately, there are steps people can take to cope with cancer-related fatigue.

• Related topic: Weakness and Fatigue in Cancer: What Causes Them and How Are They Treated?

What Causes Breast Cancer-Related Fatigue?

Breast cancer-related fatigue can occur as a symptom of breast cancer or as a side effect of treatment. A 2019 study followed 332 women referred for mammography and compared fatigue levels in those diagnosed with cancer with those who were not. Fatigue was greater in women diagnosed with breast cancer and was most severe during the first 6 months after diagnosis.

Breast cancer-related fatigue may result from many factors, including:

• The disease itself
• The psychological impact of a cancer diagnosis
• Side effects of cancer treatments

Hormonal Changes During Breast Cancer Treatment

We may recommend hormone therapy to treat breast cancer and reduce the risk of recurrence. The hormone estrogen fuels some types of breast cancer. Suppressing estrogen can reduce the risk of recurrence of these breast cancers. Treatment may include hormonal therapies such as:

• Tamoxifen
• Raloxifene
• Anastrozole (Arimidex) or aromatase inhibitors such as exemestane (Aromasin)

However, changes in hormone levels can cause symptoms similar to menopause. Hormones used to treat breast cancer can cause various side effects, including:

• Hot flashes
• Joint and muscle pain
• Exhaustion

Chemotherapy

Fatigue is among the most common side effects of chemotherapy. The cause of fatigue during cancer treatment is not always clear and may involve several factors.

For example, chemotherapy can lower red blood cell and then white blood cell levels, which may cause fatigue. Chemotherapy can also trigger nausea and vomiting, which can lead to dehydration and associated fatigue.

Chemotherapy and other cancer treatments can also cause fatigue by:

• Changing hormone and protein levels in ways that can cause inflammation
• Producing toxic substances that alter how cells work in the body
• Triggering a buildup of dead cells that the body must work hard to remove
• Damaging tissues that the body must work hard to repair

Radiation Therapy

People receiving radiation therapy for breast cancer may experience certain physiological changes because their cells receive radioactive rays, and this can cause fatigue. According to a meta-analysis conducted in 2021, the severity of radiation-induced fatigue depends on:

• The type of radiation therapy
• The radiation dose
• The amount of tissue receiving radiation
• Whether the person is receiving additional cancer treatment

In addition, radiation therapy is usually given 5 days a week. Traveling for treatment every day can cause tiredness and exhaustion.

Mental Health

Although people experience a cancer diagnosis differently, anxiety and depression are common. These feelings can drain a person's energy and also lead to inadequate sleep, which may cause tiredness and exhaustion.

A 2020 review of research reported that women who had survived breast cancer and reported fatigue also frequently experienced depression, insomnia, and cognitive dysfunction.

Tips for Managing Fatigue

There are several approaches a person can try to help manage cancer-related fatigue:

1. Consult a specialist:

A cancer specialist can be consulted to identify possible causes of fatigue. Specialists can help you address it by reducing current medication or medication doses, referring you for nutritional counseling, or helping you obtain mental health support.

2. Exercise:

Physical activity might be thought to make fatigue worse. However, research suggests that exercise may help reduce its intensity both during and after cancer treatment. A 2017 meta-analysis compared different interventions for cancer-related fatigue. It found that exercise and physiological interventions were more effective at reducing fatigue than drug treatment. Nevertheless, patients should consult their doctor before starting an exercise program to determine the best program.

3. Drink plenty of water:

People undergoing chemotherapy or radiotherapy may experience nausea, vomiting, and diarrhea, all of which can cause dehydration (fluid loss). Dehydration can also cause fatigue. A person receiving cancer treatment should therefore take care to drink plenty of fluids to prevent dehydration and associated fatigue.

4. Receive complementary treatment:

According to the US National Cancer Institute, complementary medicine may help reduce fatigue associated with cancer treatment. Although there is little research on the effects of complementary treatments on breast cancer-related fatigue, there are some general suggestions for coping with it. What examples of complementary medicine might help patients? Hypnosis/meditation, massage, acupuncture, reiki, yoga, Tai Chi...

According to a study in patients with breast cancer, complementary treatment approaches with strong evidence levels (A and B) are listed in the table below.

5. Balance rest and activity:

Too much rest weakens the body, while excessive activity can also cause fatigue. The important thing is to maintain a balance between the two. Taking short breaks during the day when needed, or being physically active after brief periods of sleep such as naps, can help maintain this balance.

6. Get support:

One way to conserve energy is to accept help from others with daily tasks and responsibilities. People should be able to ask family members and friends for help with tasks such as cleaning or shopping. Support can also include professional counseling. Behavioral therapy and mindfulness-based stress reduction may help reduce cancer-related fatigue in some people.

When Should You See a Doctor?

Although breast cancer-related fatigue is common, a specialist should still be consulted about it. Specialists may need to investigate the precise cause of breast cancer-related fatigue and develop an appropriate treatment plan. The sooner people speak with their doctor, the sooner treatment to conserve energy can begin. You can consult your doctor if you experience:

• Being unable to get out of bed
• Feeling extremely weak
• Difficulty sleeping
• Lack of motivation
• Problems concentrating

Conclusion

Breast cancer and its treatment may lead to increased fatigue. Breast cancer-related fatigue generally varies according to cancer type, symptoms, and the type and duration of treatment. Individual factors such as age, overall health, and response to treatment may also play a role.

Energy levels often improve a few months after cancer treatment ends. However, it may take several months for fatigue to disappear completely.

Fortunately, treatments and lifestyle changes can reduce fatigue and improve energy levels. You can consult a specialist about how to cope with cancer-related fatigue.