Whole brain radiation therapy (WBRT) is a medical treatment that uses high-energy X-rays to treat the entire brain. It is administered over a series of daily sessions. WBRT helps manage symptoms and slow the growth of certain conditions affecting the brain. It functions by damaging the DNA of rapidly dividing cells, like cancer cells, hindering their ability to multiply and spread.
Why Whole Brain Radiation is Used
Whole brain radiation is often prescribed for individuals where cancer has spread to the brain from another part of the body, known as brain metastases or secondary brain tumors. Cancer cells growing within the brain can increase pressure inside the skull, leading to symptoms such as headaches, nausea, or increasing drowsiness. WBRT can help alleviate these symptoms by shrinking tumors and reducing pressure.
This treatment is particularly relevant when there are multiple brain metastases, or when individual tumors are too small to be detected by imaging, or are difficult to remove surgically. The goals of WBRT are to control the disease, improve or prevent neurological symptoms, and potentially extend life.
WBRT also serves a preventative role in some cases, known as prophylactic cranial irradiation (PCI). This is commonly used in aggressive cancers with a high likelihood of spreading to the brain, such as small cell lung cancer. PCI aims to destroy microscopic cancer cells that may have reached the brain, reducing the risk of future brain metastases and potentially improving overall survival. The blood-brain barrier can make it difficult for chemotherapy drugs to reach cancer cells in the brain, making radiation a preferred method for prevention.
The Whole Brain Radiation Procedure
Undergoing whole brain radiation involves a careful planning process to ensure precise treatment delivery. Patients initially have imaging scans, such as a CT scan or MRI, of their head. These scans provide detailed images that allow the radiation oncology team to map the exact areas to be treated and design a personalized treatment plan.
A custom-made immobilization mask is created during a planning session, often called a simulation. This mask is made from a warm, pliable plastic mesh molded over the patient’s face and head. As it cools, the mask hardens, forming a snug fit that helps the patient remain perfectly still for each treatment session.
Treatment sessions are administered daily, five days a week, over several weeks. Each session might last around 10 to 30 minutes. The patient lies on a treatment table while wearing their custom mask. The radiation machine moves around the patient, delivering beams to the entire brain. Patients do not feel anything during the actual radiation delivery, though they may hear the machine moving.
Managing Side Effects of Whole Brain Radiation
Whole brain radiation can cause various side effects, categorized as acute (short-term) or late (long-term). Acute side effects appear during or shortly after treatment, typically resolving within weeks to months.
Common acute side effects include:
Fatigue is a common acute side effect, which can persist for several weeks after treatment. Managing fatigue involves adequate rest, conserving energy, and light physical activity.
Hair loss on the scalp, often starting about two weeks into treatment. Hair usually regrows within three to six months, though it may be thinner or have a different texture. Scalp care includes using gentle shampoos and lotions, and protecting the scalp from sun exposure.
Nausea and vomiting, which can sometimes occur within hours of the first treatment. Anti-nausea medications are commonly prescribed. Eating smaller, more frequent meals, avoiding spicy or strong-smelling foods, and staying hydrated can also help.
Skin irritation on the scalp, resembling a sunburn with redness, dryness, or itching. Gentle skin care with mild soaps and sun protection are recommended.
Headaches, which can occur due to brain swelling. Doctors may prescribe steroid medications to reduce swelling.
Cognitive changes, including short-term memory issues or difficulty concentrating.
Long-term side effects can emerge months to years after treatment, including more significant cognitive issues like declines in learning and memory. Strategies to minimize these effects include newer radiation techniques like hippocampal-avoidance WBRT, which limits radiation exposure to the hippocampus, a brain region involved in memory. Supportive care and cognitive rehabilitation can be beneficial. Regular follow-up with the care team is important to monitor and manage any persistent or emerging side effects.
Outcomes and Considerations After Whole Brain Radiation
Whole brain radiation therapy aims to achieve several outcomes, including shrinking tumors, alleviating neurological symptoms, and delaying disease progression. Many patients experience an improvement in symptoms like headaches, nausea, or motor function within days or weeks of starting treatment. This relief can significantly improve a patient’s daily comfort and overall well-being.
WBRT can substantially control tumor growth within the brain. However, the duration of this effect can vary, and WBRT does not always translate into a significant increase in overall survival, especially when compared to more targeted treatments in certain patient groups. WBRT has been shown to improve quality of life for some individuals with multiple brain metastases.
After completing WBRT, ongoing follow-up care is recommended to monitor for any recurrence of cancer and manage potential long-term effects. This involves regular brain MRI scans, which help detect any new tumor growth at an early stage, allowing for timely intervention.
Considerations after WBRT also include potential long-term quality of life adjustments. While some cognitive effects may improve over time, others could persist, impacting memory, attention, or overall brain function. The care team plays a role in addressing these concerns, coordinating further evaluations, and providing guidance on supportive therapies to enhance long-term well-being.