Radiation in treating secondary brain tumours
Secondary or metastatic brain tumours arise from cancers originating in other parts of the body. These most frequently arise from primary tumours in the lung, breast and skin and can result in multiple tumours within the brain.
Radiation is frequently used to treat brain tumours, but the mechanism by which to treat multiple secondary tumours has been a topic for debate. Radiosurgery directs highly-focused radiation only to the sites of tumour metastases and current guidelines suggest that this approach should only be used in cases where there are fewer than four tumours in the brain. Larger numbers are frequently treated by whole-brain radiation therapy. This, as its name suggest, treats the entire brain but can be associated with notable cognitive side effects. However, there is controversy over which approach should be used for larger numbers of tumours and the challenge has been to define in which circumstances each technique is optimal.
A University of Colorado Cancer Centre study published in the Journal of Thoracic Oncology shows that in a subset of patients with tumours associated with specific genetic mutations, local radiosurgery may be the best choice even when the patient has a larger number of tumours.
The researchers assessed the clinical records of a group of patients who had been treated using radiotherapy either in the form of whole brain radiotherapy or radiosurgery and then correlated this with response rates. They found that for patients with a specific genetic mutation, local radiosurgery was the best option, even when it was administered to treat more than four tumours.
One of the challenges in the development of new therapies is to provide the most appropriate treatment for each patient – an approach called personalised medicine. This study has demonstrated that people with secondary brain tumours which have a specific genetic mutation respond best to radiosurgery, even with a larger number of tumours sites, and that understanding the genetic make-up of tumours is key for the development of new therapeutic options.