Glioblastoma is an aggressive type of brain tumor, the most common and malignant brain tumor in adults. These tumors originate in astrocytes, star-shaped glial cells supporting nerve cells. Due to their rapid growth and ability to invade surrounding brain tissues, glioblastomas present a significant challenge in treatment. Radiation therapy is a standard treatment for glioblastoma.
Understanding Radiation Therapy for Glioblastoma
Radiation therapy uses high-energy rays, such as X-rays, gamma rays, or protons, to damage cancer cell DNA. This prevents cancer cells from growing and dividing, leading to their destruction. The primary purpose of radiation therapy for glioblastoma is to destroy any remaining microscopic cancer cells after surgery or to slow tumor growth if surgery is not an option.
Radiation therapy aims to maximize damage to tumor cells while minimizing harm to healthy brain tissue. This precision is achieved through careful planning and delivery techniques that direct the high-energy beams precisely at the tumor site. A common approach involves fractional dosing, where the total radiation dose is divided into smaller daily doses over several weeks. This allows healthy cells time to repair themselves between treatments, while cancer cells, which are less efficient at repair, accumulate damage.
This approach reduces impact on sensitive healthy brain tissues. Fractional delivery allows medical teams to deliver an effective cumulative dose while managing side effects. The goal is to improve patient outcomes by reducing tumor size and slowing progression.
Types and Delivery of Radiation Therapy
External Beam Radiation Therapy (EBRT) is the most common type of radiation for glioblastoma, delivered from a machine outside the body. The process begins with an initial consultation to assess the patient’s condition and discuss the treatment plan. This is followed by a simulation, involving imaging scans like CT or MRI to map the tumor’s location and shape.
Detailed treatment planning then occurs, where a specialized team uses imaging data to determine the exact angles and intensity of radiation beams, sparing healthy brain tissue. Daily treatment sessions typically last only a few minutes, with the patient positioned carefully to ensure accurate radiation delivery.
Advanced techniques such as Intensity-Modulated Radiation Therapy (IMRT) and Image-Guided Radiation Therapy (IGRT) enhance the precision of EBRT. IMRT uses computer-controlled machines to modulate the intensity and shape of the radiation beams, allowing them to conform to the three-dimensional shape of the tumor. IGRT involves imaging the tumor before or during each treatment session to ensure accurate targeting, accounting for any slight movements. Proton therapy, which uses protons instead of X-rays, is an emerging option that can deliver radiation more precisely with less scatter, potentially reducing the dose to surrounding healthy tissues.
Managing Treatment and Side Effects
Patients undergoing radiation therapy for glioblastoma may experience common side effects. Fatigue is frequent, often appearing gradually and persisting afterward. Hair loss in the treated scalp area is also expected, and can be temporary or permanent.
Skin irritation in the treated region, resembling a sunburn, can also occur, including redness, dryness, or peeling. Temporary brain swelling, or edema, is another potential side effect, sometimes leading to headaches or other neurological symptoms. These effects are closely monitored by the medical team throughout treatment.
Management strategies for these side effects include medications, supportive care, and lifestyle adjustments. Anti-inflammatory drugs, such as corticosteroids, may reduce brain swelling. Patients are often advised on gentle skin care for the treated area and encouraged to maintain adequate rest and nutrition to combat fatigue. The medical team continuously monitors the patient’s condition, adjusting supportive care as needed to manage symptoms and improve comfort.
Integrating Radiation with Other Treatments
Radiation therapy is frequently part of a comprehensive, multimodal treatment plan for glioblastoma. For instance, radiation therapy is commonly given concurrently with chemotherapy, particularly with the oral drug temozolomide.
This concurrent chemoradiation regimen, often referred to as the Stupp regimen, has become a standard of care and improves survival rates compared to radiation alone. After this initial phase, temozolomide chemotherapy is continued for several cycles as an adjuvant therapy.
Radiation also plays a significant role alongside surgery. Following maximal safe surgical removal of the tumor, radiation therapy is often administered to target any remaining microscopic cancer cells. Other emerging treatments, such as targeted therapies or tumor treating fields (TTFields), may also be incorporated into the overall treatment strategy, with radiation therapy serving as a foundational component.