Radiation therapy for brain tumours is a treatment method that uses high-energy X-rays, gamma rays, or protons to kill cancer cells or retard their growth as much as possible. Cancer cells differ from normal cells not only in their appearance but also in how fast they divide and form new cancer cells. The radiation is programmed in a way that it attacks and destroys only rapidly dividing cells, which ensures that normal cells are not affected.
External Beam Radiation Therapy (EBRT)
Brain tumours are treated using high-powered radiation sources that aim to attack only cancer cells. For highly invasive tumours, surgeons use radiation to shrink them before they can surgically remove them. Radiation therapy is very effective even as a standalone treatment for brain tumours and is also non-invasive.
There are many types of radiation therapies – EBRT, 3D conformal therapy, Intensely Modulated Radiation Therapy, Stereotactic Radio Surgery, Conformal Proton Beam Therapy, and more. These different types of radiotherapies differ in source radiation, but in all of them, a focused beam is projected towards the tumour area in the brain, which aims to kill the cancer cell.
With the advancements made in medical science, doctors are now able to guide high-energy beams in different directions using imaging techniques such as MRIs in real time. A machine sends the rays of energy to the tumour. This treatment is usually done every weekday over a course of three to seven weeks.
In brachytherapy, small seeds of radioactive substances are placed in or around the tumour surgically. This way, only local tumour areas are affected by the radiation spreading from the seeds. Once treatment is completed, the surgeon will remove these seeds via a catheter or applicator.
Before radiation therapy, your doctor may require you to undergo a couple of procedures. Some of them are:
Non-invasive, unless brachytherapy is performed
A radiation therapy regimen can last anywhere between three to seven weeks. Once the radiation regimen is completed, the doctor will ask you to come for a follow-up appointment 3-6 weeks after the last session of radiation therapy.
The doctor may ask you to get periodic PET scans to assess whether the radiation has affected your cancer and how much. On the assessment of the same, they will further guide you on the next steps you need to take. This follow-up may be carried out every 6 months after the initial sitting, to ensure cancer has not recurred.
In case of radiation therapy has been used to shrink the tumour before surgery, the doctor will assess your fitness and your ability to handle an invasive procedure following which they will guide you for the surgery. It is ideal to report any and all side effects to your doctor during these follow-up visits.
Some of the risks posed by radiation therapy are:
Most side-effects of radiation therapy such as mood imbalances, anxiety and nausea are mild and resolve on their own and fairly quickly. However, it is advised to report any and all side effects to your oncologist.
As far as cancer is concerned, the response of cancer to treatment is quite subjective. In most cases, cancer responds well within a few weeks of radiation therapy. If the aim of the therapy is to shrink cancer, then this sign is followed up with surgery, which prolongs the recovery period due to its invasiveness. In case cancer does not respond to the therapy, the oncologist may suggest alternative treatments.