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Treatment of tumours > Radiotherapy

This works by delivering tiny packets of energy known as photons to a tumour. The photons disrupt the DNA of the tumour cells and prevent them dividing and reproducing. The method used to produce the photons may differ, but their effect remains the same.Radiation therapy (also known as radiotherapy) is used

  • to treat tumours which cannot be removed by surgery
  • to treat tumours which can only be partially removed by surgery
  • to destroy abnormal cells in tissues surrounding a tumour

Radiotherapy is the use of high-powered rays (ionizing radiation) to damage tumour cells and stop them from dividing. The effect will depend on the size and type of the tumour and varies from patient to patient. What can be hoped for will be somewhere on the following scale:

  • the tumour will grow more slowly
  • the tumour will stop growing
  • the tumour will shrink
  • the tumour will disappear

The aim of radiotherapy is always to inflict the greatest possible damage to tumour cells with the least possible damage to healthy tissue. This is possible because normal tissue is better at recovering from the adverse effects of radiotherapy than tumour tissue. Radiotherapy can be delivered in a number of ways, dependent on the type and location of the tumour.

External Beam Radiation Therapy

This is the standard form of radiotherapy used to treat tumours in all parts of the body, as well as the brain. The ionizing radiation in this case is produced by an electrical device called a linear accelerator. In neuro-oncology, this form of therapy is used in the treatment of malignant tumours such as gliomas. It can slow down tumour growth and relieve symptoms where surgery is not appropriate or, as a supplement to surgery, to treat residual tumours or to "mop up" abnormal cells around the tumour site. Even where surgery cannot be attempted, radiotherapy can prove beneficial in extending and improving the quality of life.

External beam radiation therapy is given in a number of "fractions" - small doses administered over a number of days or weeks. This is to enable normal tissue to recover between treatments while, at the same time, causing maximum damage to tumour cells.

Stereotactic Radiotherapy

In this form of radiotherapy, stereotactic techniques enable radiation to be administered to the tumour or other lesion with total precision, thus allowing much more intense doses to be given at a time. This accuracy is achieved by the use of a specially designed frame fitted to the patient's head. With the frame in place, an MRI scan is taken and a computerised "model" of the head (including the brain and the tumour) constructed. Using this model, the beams of radiation can be aimed very precisely.

Stereotactic radiotherapy is a mainstay of brain tumour treatment. However, in my opinion, talk of "neurosurgery without the knife" can be misleading if it conveys an impression of a machine which can zap a brain tumour and destroy it. No form of radiotherapy can physically remove a tumour.

There are two basic varieties of stereotactic radiotherapy:

  • Gamma Knife
    The Gamma Knife was developed in the 1960s by the pioneering Swedish neurosurgeon Lars Leksell who also coined the term "radiosurgery" to describe its effects. It uses the radioactive isotope cobalt-60 as a source of generating ionizing radiation and delivers 201 separate beams of radiation focused to intersect at the target. It can be an effective means of administering radiotherapy to certain tumours, and good results can often be achieved. The major advantage of this form of stereotactic radiotherapy is that it involves only one session of treatment.
  • FSR
    Fractionated stereotactic radiotherapy (FSR for short) is a more recently developed technique for delivering ionizing radiation to a specific, defined target in the brain. Unlike the gamma knife, FSR uses a specially adapted form of the LINAC to produce the radiation (thus making the system, at least potentially, more widely available). The other major difference is that this treatment is given in a number of small doses (fractions) over a period of time. This takes account of the fact that tumour cells are most sensitive to the damaging effects of radiation when they are actively dividing. As not all cells divide at the same time, spreading the therapy over a number of sessions provides a greater chance of catching more cells at their most vulnerable point.