The way children with leukaemia respond to their treatment is to be studied by comparing the effects of two of the drugs currently used to tackle the condition.

The University of Sheffield Medical School will carry out the study on youngsters suffering from acute lymphoblastic leukaemia, the most common childhood cancer.

The work has been supported by a grant of �160,000 from the Leukaemia Research Fund (LRF).

Dr David Grant, LRF scientific director, said: "This research will have a major impact on how we treat children with leukaemia.

Side effects

"The more we understand about these drugs, the more we can improve their effectiveness for the patient."

The researchers will be looking at 6-thioguanine and 6-mercaptopurine.

Dr Lynne Lennard, of the Royal Hallamshire Hospital, said: "Both these drugs form part of the long-term treatment for leukaemia and are very useful for most children.

"We want to learn why some children experience side effects whilst others do not."

She added the way in which children's bodies handle standard treatment for leukaemia has a significant impact on their survival.

Leukaemia is diagnosed in 500 children in the UK a year, most common in two to five year olds.

The survival rate is 80%.