Researchers in Canada and the US have found the first genetic markers indicating whether chemotherapy would be effective in treating patients with a certain type of brain cancer.

The finding means that patients need only have the treatment if it is known to work for them.

Chemotherapy involves a variety of powerful anti-cancer drugs and has side-effects such as nausea, vomiting, hair loss and fatigue.

The researchers, from Massachusetts General Hospital and the London Regional Cancer Center in Ontario, hope to find more genetic markers to ensure patients only get treatments that will help them.

Useful treatment

Dr Gregory Cairncross is a brain cancer specialist at the London Regional Cancer Center.

He worked on the study, which is published in the Journal of the (American) National Cancer Institute.

He said: "It now will be possible at diagnosis to examine patients' tumours for these genetic changes and determine right away whether chemotherapy will be helpful.

Genetic clues were found

"For those who have this genetic pattern, we know that chemotherapy has an excellent chance of shrinking or even eliminating their tumour.

"And those patients whose tumours would not respond to chemotherapy can avoid the side-effects of those powerful drugs."

His colleague, Dr David Louis of Massachusetts General Hospital, said: "This is the first time we've been able to define which brain tumours are going to respond to chemotherapy."

Other applications

The characteristics of the tumours were uncovered using a process called molecular genetic analysis.

This has been used in a similar way for other types of tumour, most recently to identify types of breast cancer susceptible to treatment with the drug herceptin.

The new discovery does the same for a type of brain cancer called anaplastic oligodendroglioma, a cancer which occurs most often in young adults.

Oligodendrogliomas account for about 10% of all brain tumours.

Combined research

The study's findings result from separate research carried out at the two centres.

The Massachusetts team had identified a number of genetic variants in oligodendrogliomas.

The London team had discovered that oligodendrogliomas were sensitive to chemotherapy drugs, and that treatment was successful in approximately two-thirds of patients.

When the groups teamed up, they found that the patients who had been treated successfully had suffered tumours with part of a particular chromosome - "chromosome 1" - missing.

Those patients whose tumour had all of chromosome 1 were unlikely to benefit from the treatment.