Radiation therapy is a common treatment for brain cancer. While it can effectively target and destroy cancer cells, it can also cause side effects. The side effects of radiation therapy for brain cancer vary depending on the location and dose of radiation and other individual factors.

Radiation therapy for brain cancer is a treatment approach that involves using high-energy radiation to target and destroy cancer cells in the brain.

Doctors commonly use radiation therapy as part of a comprehensive treatment plan for brain tumors, alone or in combination with other treatments, including surgery and chemotherapy.

During treatment, people may experience feelings of depression, stress, and difficult thoughts or feelings. People may find it helpful to speak with a mental health professional.

This article looks at the different side effects that may occur from radiation therapy on the brain and how to reduce and manage them.

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According to the American Cancer Society (ACS), radiation therapy on the brain can cause the following short-term side effects:

Some of these side effects, including seizures and headaches, can be a sign that the brain has swollen. This is considered a medical emergency.

Early side effects

Early side effects manifest during or within 1 month of treatment. They are typically short-term, mild, and manageable.

The primary early side effects include fatigue and skin changes.

Late side effects

Radiation to the brain can lead to late side effects that may emerge anywhere from 6 months to several years after treatment ends.

These delayed effects can include significant issues, such as memory loss, symptoms resembling a stroke, and impaired brain function.

Additionally, there is a possibility of an increased risk of developing another tumor in the treated area, although this occurrence is uncommon.

Fatigue is a common side effect of many cancer treatments, including radiation therapy. Up to 90% of people receiving radiation may experience some level of fatigue.

Getting plenty of rest, conserving energy, and engaging in light physical activity is important. Adequate nutrition and hydration are also essential.

Managing fatigue

A person should speak with their healthcare team if they:

  • feel very fatigued
  • cannot perform their usual activities
  • feel very tired, even after resting and sleeping

To help combat fatigue, a person can:

  • try to make a plan that balances activity and rest
  • choose activities that are relaxing
  • plan times to rest
  • eat a balanced diet
  • stay hydrated

Radiation to the head may cause temporary hair loss. This can include the eyebrows and eyelashes.

Hair loss typically occurs 2–3 weeks after beginning treatment.

Managing hair loss

It may not be possible to prevent hair loss during radiation therapy.

However, according to the ACS, hair usually grows back within 3–6 months after completing treatment. Dermatologists may be able to prescribe medications to improve the rate at which the hair grows back.

In the meantime, a person can:

  • wear a wig or comfortable scarf
  • use sunscreen on their scalp and wear a hat when outside
  • apply lotions and conditions, if the scalp feels itchy

A person may develop radiation dermatitis. The skin at the radiation site may become inflamed, dry, or itchy.

These symptoms typically occur 1–3 weeks after receiving radiation therapy.

Managing skin changes

Doctors or dermatologists may recommend a skin care regime, if someone experiences skin changes, such as inflammation, dryness, or itchiness.

This may include using mild, non-irritating soaps and moisturizers, avoiding exposure to extreme temperatures, and protecting the treated area from the sun.

The American Academy of Dermatology Association (AAD) notes that people should:

  • wash the skin very gently using warm water
  • apply a gentle, low-pH cleanser, if necessary
  • avoid using sponges, washcloths, and loofahs
  • avoid shaving the area
  • apply moisturizer every day

Before applying any lotions or creams, a person should consult with their healthcare team.

Although nausea and vomiting are common when the treatment involves the stomach, it can also be a general side effect regardless of the treatment area.

Radiation therapy may cause nausea and vomiting in 50–80% of people. People may also experience a loss of appetite.

Radiation sickness typically resolves a few weeks after a person has finished treatment.

Managing nausea and vomiting

Doctors can prescribe medications to manage these symptoms.

Eating small, frequent meals and avoiding greasy or spicy foods may also help.

Some individuals may experience cognitive changes, such as difficulty with memory, attention, or problem-solving.

Radiation therapy can damage the brain cells. These changes may appear years after the treatment.

Managing cognitive changes

If a person experiences cognitive changes, such as difficulty with memory or concentration, some strategies can help.

Breaking tasks into smaller, manageable steps, using reminders or organizational tools, and engaging in mental exercises or puzzles can all help.

People should also consider seeking support from occupational therapists or neuropsychologists, who can provide cognitive rehabilitation techniques.

Radiation therapy may cause temporary headaches. The headaches may be due to swelling of the brain, which requires prompt treatment.

Managing headaches

Over-the-counter pain medications may provide relief, but it is essential to consult the healthcare team before taking any medication.

Brain tumors and radiation therapy can both increase the risk of seizures.

A person should speak with a healthcare team if they experience seizures. This is because they can be a sign of brain swelling.

Managing seizures

Doctors can prescribe medications called anticonvulsants to prevent seizures or manage them if they occur.

Cancer Research UK notes that radiation therapy can cause short-term swelling, raising the pressure in the brain.

A person may experience:

  • headaches
  • nausea
  • seizures

Brain swelling can develop over days or weeks.

Although a person usually receives medications to prevent this from happening, a person should contact a doctor if they experience any signs of brain swelling, as it is considered a medical emergency.

Treating brain swelling

Doctors can treat brain swelling using corticosteroids. If a person is unable to take steroids, a doctor may administer a drug called bevacizumab.

Both stereotactic radiotherapy and radiosurgery are specialized forms of radiation therapy that deliver high-dose radiation to specific targets.

Stereotactic radiotherapy and radiosurgery are generally associated with fewer side effects than standard radiation therapy. This is due to their highly targeted nature, which helps spare the surrounding healthy tissues.

Stereotactic radiotherapy and radiosurgery can cause specific side effects depending on the treatment location though. For example, when used for brain tumors, they can result in edema in the surrounding brain tissue.

The Canadian Cancer Society notes that a person can experience side effects at any time during treatment.

Most side effects resolve after a person finishes treatment. This can take a few weeks to 2 months. Other side effects may continue for longer while the healthy cells recover.

Late side effects may resolve over time. However, others may be permanent.

To reduce and manage the side effects, people can discuss their symptoms with their healthcare team, who may be able to offer advice and guidance.

People can manage their side effects by:

  • engaging in regular exercise, if possible, but they should avoid starting a new, rigorous training program without first consulting their healthcare team
  • prioritizing resting
  • seeking support from friends and family
  • limiting alcohol, tobacco, and caffeine
  • drinking plenty of fluids
  • eating a balanced and healthy diet
  • working with a dietician to create a meal plan, if appetite is an issue

Radiation therapy for brain cancer can lead to side effects depending on the specific treatment technique used and individual factors. Late side effects may also occur months or years after treatment.

However, advances in treatment planning and precision techniques, such as stereotactic radiotherapy and radiosurgery, have helped minimize side effects compared to standard radiation therapy.

People need to discuss potential side effects with their healthcare team, as they can provide personalized information, support, and management strategies to optimize their treatment experience.