In studies to determine the optimal treatment for polycythemia vera, 431 previously untreated patients whose disease met established diagnostic criteria were entered into a prospective, randomized controlled trial between 1967 and 1974. Three treatment regimens were used: phlebotomy alone, chlorambucil supplemented by phlebotomy, or radioactive phosphorus supplemented by phlebotomy. Despite minor differences in age and sex, the three groups were comparable in initial hematocrit, white-cell and platelet counts, and disease-related symptoms. The median duration of follow-up is now more than 6 1/2 years. As of February 15, 1980, there were no statistically significant differences in survival among the groups. However, the risk of acute leukemia in patients given chlorambucil was 2.3 times that in patients given radioactive phosphorus and 13 times that in patients treated with phlebotomy alone. The increased incidence of leukemia during chlorambucil treatment is statistically significant (P less than or equal to 0.002); accordingly, the Polycythemia Vera Study Group has discontinued the use of chlorambucil in the treatment of polycythemia vera.

Platelet mean life span (MLS) and platelet production were measured in 35 patients with idiopathic thrombocytopenic purpura (ITP) and in 21 healthy subjects.The mean platelet production in ITP was 2.3 times normal : the highest values were 3-5 times normal. There was a highly significant negative correlation between platelet production and peripheral platelet count. With platelet counts above 50000 pl, platelet turnover was within the upper part of the normal range, but with lower platelet counts, turnover progressively increased. It is concluded that the bone marrow in ITP increases platelet production in response to a low platelet count and that this response does not differ from that hitherto known to occur in man and animals rendered thrombocytopenic by thrombopheresis.KARPA'I".

Platelet survival studies were performed in three groups of males: 10 healthy young students, 8 healthy middle‐aged men and 8 haematologically normal subjects with mild to moderate cardiovascular diseases. Two mathematical functions were used in order to obtain platelet mean life span. (MLS) according to the principle of Mills (1946). The two functions were equivalent for the estimation of platelet MLS. In all groups studied, the range for platelet MLS was wide, but was most pronounced in the group of subjects with cardiovascular diseases. The mean platelet MLS for young students was higher than the mean for healthy middle‐aged men, and the mean for the latter was higher than the mean platelet MLS in the group of subjects with cardiovascular diseases. The differences between these three groups were, however, not statistically significant. The means for platelet destruction rate and turnover were equal in the two groups of healthy volunteers studied. In the group of subjects with cardiovascular diseases the mean for platelet destruction rate and turnover exceeded the means for healthy volunteers but not significantly so.

This paper reports the results of cytogenetic studies in a consecutive series of 64 patients with polycythemia vera, 57 of whom could be followed prospectively. The median length of the cytogenetic observation time was 93 months (range, 24 to 224 months) after diagnosis. Clonal chromosome abnormalities were observed initially in 11 patients (17%) and later during the course of the disease in another 20 patients. An abnormal karyotype was found in 71% to 80% of the patients who were examined after the development of myeloid metaplasia, myelofibrosis, or leukemia. Patients treated with myelosuppressive agents showed a significantly greater risk of chromosome abnormalities developing than did patients who had been phlebotomized. Acute leukemia developed in eight patients, all of whom had been treated with myelosuppressive agents. A chromosome abnormality preceded the leukemia in only two of the patients. The initial presence of an abnormal karyotype did not predict a greater risk of development of leukemia. No consistent relationship was demonstrated between the occurrence of chromosome abnormalities and the development of myeloid metaplasia and/or myelofibrosis, which was observed in 42% of the patients. The chromosome abnormalities followed a nonrandom pattern, and those most frequently observed were trisomies for 1 q, 8, 9, or 9p and deletion of 20q. Deletions seem to be common and were found in 14 patients.