Factors associated with prolonged survival in chronic myeloid leukemia.

Four patients who demonstrated unusually prolonged survival with Philadelphia chromosome positive Ph' (+) chronic myeloid leukemia (CML) were analyzed for factors associated with survival. Survival duration from initial diagnosis ranged from 120 to 222 months, with a mean of 170 months. At diagnosis, age, symptoms, liver or spleen size, hematocrit, white blood cell count, absolute peripheral myeloblast plus promyelocyte count, and uric acid did not have unique prognostic significance. At diagnosis all four patients had normal or low-normal platelet counts, (range: 170,000 to 248,000/mm3). Thrombocytopenia occurred during treatment in three patients. None of the four patients, however, developed severe marrow hypoplasia or leukopenia during treatment for the chronic phase. Cytogenic studies performed from 103 to 156 months after diagnosis did not reveal a large subpopulation of marrow cells with a normal karyotype or cells with the XO genotype in the male patients. These observations suggest that prolonged survival in CML 1) is not contingent upon intensive treatment resulting in marrow hypoplasia, and 2) does not require the persistence of a clone of karyotypically-normal bone marrow cells or a clone of marrow cells in males which has lost the Y chromosome. A normal or low-normal platelet count at diagnosis may be a favorable prognostic indicator.