Fifty years of studies of the biology and therapy of childhood leukemia.

Pearson not criticize these data? On the contrary, I agree with Prof Pearson’s other criticism. If, in fact, some patients with a particular risk are precociously excluded from a therapy protocol, the calculation of this risk for the whole population will be wrong. That was the case in the phlebotomy branch of the P.V.S.G. protocol, where the oldest and those with vascular risk factors or thrombocytosis have been excluded and treated otherwise. So, the true risk of leukemia could be under-estimated. But this is not a criticism of the method of calculation; this a criticism of the design, or of the fulfilment, of the protocol.