Natural history of smouldering leukaemia.

The natural history of 45 cases of smouldering leukaemia has been studied. Males and females were equally represented, with a median age of 60.5. The median survival of the whole group was only 20 months, but rare cases lived 10 years or longer. 38% developed acute leukaemia; the remainder usually died of the results of marrow failure. Although it was possible to divide these marrow dysplasias morphologically into 3 major subgroups (refractory anaemia with excess of myeloblasts, chronic myelomonocytic leukaemia and chronic erythraemic myelosis), several displayed transitional features. Many showed refractory macrocytosis at diagnosis. The survival of the 3 groups was similar, though patients with high monocyte counts tended to present with less anaemia and fared rather better than the others. Statistical analysis suggests that increasing age, severe anaemia, thrombocytopenia and hepatomegaly are associated with a poor prognosis. Chemotherapy, when attempted, was usually unsuccessful.