Brain Tumors: Primary - Radiotherapy

Drugs Used With Radiation

A number of drugs may be used along with radiation that may increase the effectiveness of the treatment.

Radioprotectors. They protect healthy cells during radiation.

Radiosensitizers. These agents make cancerous cells more sensitive to radiation. For example, combinations of the radiosensitive drugs iododeoxyuridine, 5-FU, and hydroxyurea are promising. Such treatments usually require aggressive use of other protective agents to prevent severe side effects.

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Radioenhancers. These drugs, such as topotecan, increase the effects of radiation. Topotecan combined with other drugs, such as thiotepa and carboplatin, may help children with neuroblastoma and brain tumors. A 2002 study using topotecan for glioblastoma multiforme was disappointing, but different methods of administration or other similar drugs may be useful. Efaproxiral, an investigative agent that increases oxygen in the brain, is showing promise as a radioenhancer.

Side Effects of Radiation

Common Side Effects. Side effects of radiotherapy include hair loss, nausea and vomiting, and fatigue. In some cases, radiation may worsen some existing symptoms of brain tumors, seizures, difficulty in swallowing, and movement problems. Fluid build-up (edema) may occur. Such side effects are usually temporary and treatable with steroids. Patients often develop problems in thinking and concentration after radiation treatments. One study suggested that administering oxygen under pressure, called hyperbaric oxygen, may provide some small benefits. It is sometimes difficult to tell symptoms of the disease from those of the treatments.

Tissue Injury. Radiation necrosis (total destruction of nearby healthy tissue) occurs in about 25% of patients treated with radiation. This condition is highly associated with reduction in mental functions. In nearly half the cases of standard radiation therapy, additional surgeries are needed on areas injured by radiation. Other treatments that are showing promise for treating necrotic tissue include administration of oxygen and pentoxifylline (an agent that improves blood flow).

Secondary Tumors. Of concern is a study reporting a few cases of second tumors developing in the areas treated with radiosurgery. The incidence appears to be very low, but experts suggest continued surveillance may be appropriate.

Specific Issues in Radiation Therapy for Small Children. In small children, radiation therapy can impair growth and learning. Precise radiation techniques, such as three-dimensional conformal radiation therapy, may help some children while limiting the injury to healthy brain tissue. Growth hormone is often used after radiotherapy and is effective in restoring growth in many of these children. Although there has been some concern that growth hormone may increase the risk of relapse, a 2000 study reported that, in fact, these children had a lower rate of recurrence than those who did not take growth hormone.