The UKALL 2003 trial initially chooses your child's treatment regimen based on a series of diagnostic tools - prognosis factors based on previous experience and lab tests. Thus ... I will try to reinvent the wheel as I promised not to do previously.
If your child is under one year old, s/he will go onto another protocol trial.
If your child's ALL is effecting the White Blood B-cells (see the post on Haematology), s/he will follow a different protocol developed by the UK Childhood Cancer Study Group (sorry – I don't know any details right now). UKALL 2003 is only involved with T-cell ALL.
If the child has any of various genetic abnormalities which have been shown to put the child at a higher risk of later relapse, then s/he will automatically be put on Regimen C.
If your child is older than 10 years old, then s/he will automatically be put on Regimen B.
If your child has an initial White Blood Count (i.e. mostly malformed T-cells) greater then 50 (x 109 per litre), then s/he will go on Regimen B.
Kezia “passed” all the above (phew!) except the last one. So she went on Regimen B. I was confused at first between Regimens B and C – don't worry, in the first stage of treatment Regimens B and C are the same. They differ in later stages of treatment.
They then look at the number of lymphoblasts in your child's bone marrow at Days 8, 15 and 28 of the initial treatment.
If at Day 8 and the child is on Regimen B and the blood-producing cells of the bone marrow show more than 25% lymphoblasts, then s/he is automatically transferred to Regimen C. S/he is also thus classified a Slow Early Responder (SER). This was the case with Kezia (and by the way H.).
If your child is on Regimen A and there are more than 25% lynmphoblasts at Day 15, then s/he will go onto Regimen C.
If your child is on Regimens A or B and has less than 25% lymphoblasts at Days 8 or 15, then s/he will stay on the same Regimen (course of treatment).
If your child is older than 16 years, s/he will continue on Regimen B regardless of the Bone Marrow results.
The next bone marrow test is at Day 28 – the end of the Induction phase. If your child has already been assigned to Regimen C, this will not make any difference.
However, if your child is on either Regimens A or B, then the 28 day count can decide the future course of treatment. If your child still has between 5% and 25%, s/he will go onto the Regimen C treatment. More than 25% s/he will stop being part of the UKALL2003 trial and will be treated under another protocol.
Less than 5% of lymphoblasts, your child will be allocated randomly to Regimens A or B.
This is really one of the objectives of the trial. As I said before, Regimen A is the least intensive/aggressive and Regimen C is the most intensive/aggressive. The drugs for killing the leukaemia attack both good and bad cells. They want to see if a low-level of leukaemia, needs less amounts of drugs to kill the disease. They cannot take too many risks with our treatment, so only children with less than 25% at days 8/15 and less than 5% at Day 28 will really go on to experiment between Regimens A (less aggressive) and B (more aggressive).
I'll about the differences between the regimens in a later post.