Test to refine leukaemia therapy

By Matthew Hill
BBC West health correspondent

Amelia is receiving a high dose of chemotherapy

Children with a form of blood cancer are being offered genetic tests to enable chemotherapy doses to be adjusted to match the severity of their condition.

The use of the tests is already producing promising results.

Amelia Bishop looks like any three-year-old - but she is fighting a potentially fatal blood cancer, known as acute lymphatic leukaemia.

Her mother Ros, says it was a terrific shock when Amelia was diagnosed 18 months ago.

But it would have been far more difficult to deal with if Amelia had been older.

Speaking at her home in Coln St Alwyn near Cirencester, Ros said: "I feel very lucky she was the age she was at diagnosis.

"She doesn't view herself as an ill person and going to hospital is just a routine part of her life - she doesn't know anything different."

Amelia was given a high dose of chemotherapy, which meant she had to endure more side effects.

But Ros and her husband Craig are content that the high dose is necessary, because genetic testing revealed that Amelia had a severe form of the disease.

Craig said: "Of course we are devastated that she is in a higher risk category.

"But I am very happy she is on the more aggressive type of treatment, for my psychological well-being and the fact that we are doing all that science can.

"If she does not come through it then there was nothing else we could do."

Clinical trial

The Genetics Laboratory at Southmead hospital in Bristol is where the bone marrow from patients like Amelia are tested.

Dr Moppet believes the test is having a positive impact

The centre is leading a national clinical trial which started in 2003 to identify which children with the blood disease need more chemotherapy, and which ones less.

The technique looks for what is known as 'minimally residual disease'.

After a first dose of chemotherapy a tiny sample of the patient's bone marrow is taken, and the DNA analysed for tell tale patterns to find out how well the patient is responding to the treatment.

The tests are very expensive at £3,000 a time as it takes about a month to analyse each sample.

But although the results so far are preliminary, leading paediatric haematologist Dr John Moppett, from Bristol Children's Hospital, believes they have already shown that the test can improve patients' chances of survival.

He said the technique means scientists can detect tiny amounts of Leukaemic DNA that could never be seen with a microscope.

He said: "It's like looking for a needle in a haystack.

"Traditionally, the outcomes for this kind of cancer in children is about 70% -75% survival, but since this trial has been running things have improved and they are now definitely over 80%."

It will take at least six years before the results of the study are fully evaluated.

But the researchers hope the test could eventually be applied to other types of blood cancer, including those that affect adults like the bone disease myeloma.