While radiation therapy is typically used to treat malignant brain tumors or other cancers in the body, radiation therapy is also effective in treating benign brain tumors like pituitary adenomas. Radiation treatments are usually given following surgery for pituitary tumors if the surgeon cannot completely remove the tumor. Sometimes radiation treatments are used instead of surgery if the tumor cannot be removed safely.
Please note: Radiation therapy is provided at the London Regional Cancer Program of London Health Sciences Centre.
Planning and preparation
The radiation oncologist is the physician who assesses and prescribes radiation treatments for patients and works with a radiation team including dosimetrists, physicists, radiation therapists and nurses to ensure radiation treatments are given accurately and safely. The process of radiation therapy involves an initial consultation with the radiation oncologist and once a decision to treat is made treatment planning is commenced. As part of the planning process a custom plastic mask is made and this is worn for treatments in order to ensure the patients head is in the proper position and is held still for the treatments.
Following the construction of the mask a CT scan obtained with the patient in the mask is obtained and this scan allows the radiation oncologist to specify the location of the tumor to be treated as well as normal tissues to be avoided. The process of making the mask and obtaining the scan usually takes about 45 minutes. An MRI scan will often also be performed during the same visit. After the planning visit, the radiation team takes the information obtained and designs a customized radiation plan with the goal of selectively treating the pituitary tumor while avoiding uninvolved organs such as the eyes, optic nerves and brain.
Most patients can expect to start radiation treatments within 1-2 weeks
of their planning visit. Patients are usually treated on a daily basis, Monday to Friday, 25-30 treatments over 5-6 weeks. Treatments with radiation usually take 15-20 minutes per day and the most common
side effect during treatment is mild tiredness. Less often there may be some hair thinning or mild skin irritation. These side effects will usually
go away over a few weeks (tiredness, skin irritation) or months (hair regrowth).
Regular follow-up by your radiation oncologist, endocrinologist and neuro-ophthalmologist after treatment is important to monitor the success and potential long term side effects of treatment. Severe long term side effects of radiation such as vision loss, stroke, impaired thinking or a second brain tumor are very rare but can occur months to years after radiation. Monitoring of pituitary function after radiation is necessary as adjustment in pituitary hormone replacement drugs is often necessary. Scans to monitor the tumor are also performed on a regular basis (usually yearly). Pituitary tumors rarely shrink after radiation and successful radiation treatment is indicated by the absence of growth of the tumor on monitoring scans.
For more information on radiation therapy, visit the London Regional Cancer Program website.