[Chronological changes in leukemias in Hokkaido (author's transl)]

The various leukemias in Hokkaido for the past 20 years are analysed in its change of the mortality rate, the type of leukemia, and the clinical picture. The observation years are divided into 4 periods: I (1951-1957), II (1958-1962), III (1963-1967), IV (1968-1972). 1. The adjusted mortality rate of leukemia shows a rising tendency through these periods: I (1.7), II (3.0), III (3.5), IV (3.6). 2. The adjusted age-specific mortality rate of leukemia in period II, III, and IV, show a remarkable increase in all age brackets compared with period I, especially in older age brackets. The rate of the "60-69 years old" bracket gradually rises as I (3.1), II (4.8), III (5.9), IV (7.2). The rate of the "over 70 years old" bracket is I (1.3), II (1.8), III (5.0), IV (9.3). It is characteristic that these brackets has the highest mortality rate in period IV. 3. Some comparisons between period I and IV are described as follows: (1). Monocytic leukemia had decreased from 10.6% (I) to 1.4% (IV) and chronic myelogenous leukemia has slightly increased in period IV. (2). In acute type, the cases of aleukemic leukemia tends to increase in period IV and its initial symptoms changes into mild gradually. (3). In chronic type in period IV, splenomagaly is common in the initial symptom and while blood cell counts in these cases are above 10 x 10(4)/cmm.