Leukaemia test 'could save lives'

It is difficult to predict who will relapse

A breakthrough in the treatment of leukaemia patients could help more people to recover from the deadly disease.

Scientists say it could reduce the delay in diagnosing a relapse of the cancer by up to six months.

At present, the only effective way to cure chronic myeloid leukaemia is to give patients a transplant of immature cells from the bone marrow of a healthy donor to replace the cancer cells.

The possibilities for faster diagnosis and better targeted treatments could be enormous

Dr Eduardo Olavarria

This process is known as allogenic stem cell transplantation (SCT).

Unfortunately, SCT cannot entirely prevent tiny traces of the disease remaining in the blood.

The number of remaining cancer cells determines what kind of further treatment a patient requires.

But the number of cells vary enormously from patient to patient, and until now it has proved very difficult to measure exactly how many cells are left behind.

Scientists have used DNA tests to detect the presence of residual disease.

However, the practical use of such tests has been limited because they are excessively sensitive.

Consequently, results from patients who have received stem cell transplantation nearly always indicate a degree of leukaemia remaining, but could not be used to predict how many patients would eventually relapse.

Sensitive

Dr Eduardo Olavarria, of Hammersmith Hospital, London, has developed a way to make the test, called competitive PCR, much more useful.

He has developed a scale which allows doctors to ascertain whether patients are at high, low or no risk at all of relapse.

Doctors can determine not only the levels of leukaemic cells present, but also the rate at which their number is increasing.

Dr Olavarria believes this information could be of great significance for doctors trying to prescribe the most suitable treatment.

Accurate judge

For instance, stopping drugs to suppress the immune system when the level of residual leukaemia is still relatively low can be vital in preventing relapse.

Results from Dr Olavarria's trial show that almost half of those patients who relapsed were taken off their immunosuppressive drugs relatively late.

The new technique allows doctors to judge accurately when patients should stop immunosuppressive therapy.

Similarly, patients who do relapse after their operation are best treated with a booster injection of white blood cells from the original donor.

This is most effective if given before the disease progresses too far.

Making sure a patient gets the right treatment following their bone marrow transplant will give them the best chance of beating the disease

Nicola Hawe, Cancer Research Campaign

However, using current techniques, diagnosis of a relapse usually takes nine months, or longer by which time the effectiveness of the booster jab may be dramatically reduced.

The new technique could reduce this delay to as little as 90 days, with potentially life saving implications.

Dr Olavarria said: "The possibilities for faster diagnosis and better targeted treatments could be enormous.

"Competitive PCR is a much more sensitive, quicker and less painful technique than the biopsy previously required to diagnose a relapse."

Nicola Hawe, science information officer for the Cancer Research Campaign, told BBC News Online: "The beauty of this technique is the speed with which the clinician can get a predictive diagnosis.

"Knowing the likelihood of whether a patient will relapse or not will help clinicians choose the best available treatment for that patient.

"Making sure a patient gets the right treatment following their bone marrow transplant will give them the best chance of beating the disease."