On 822 cases collected from the death certificates. the suthor studied the trend of leukemia occurring in the ChugokuShikoku Distric (excluding Hiroshima Prefecture) during the period from 1951 up to June 1957, and obtained the following results. 1. Leukemia in general: a. The number of leukemia is increasing from year to year, and the cases occurring during 1956 and 1957 are three times the same during 1951 and 1952. b. The percentage of female patients was relatively small as compared with male patients; namely, 58.6 per cent male and 41.4 per ceut female, However, there is an increasing tendency in the percentage of female from year to year. c. The absolute number is greater in younger persons and it is less in older persons. As for the mortality of leukemia it is greater in infants and less in children and adolescents, but in the age over 45 years there is an incseasing tendency in the mortailty not less than that in infants. Leukemia in old age increases in absolute number and death rate from year to year, while on the contrary the death rate of leukemia in infants is decreasing. The difference in the number between male and female decreases in old age. d. It appears that there is no occupation specific to leukemia. e. Hospitalized patients occupy more than one half the total cases dying from leukemia.
f. Death from leukemia seems to have no particular relationship with seasons of the year. 2. The duration of survival in leukemia: a. The duration between the onset of leukemia and death is extremely short, that is 60.6 per cent die within three months and those surviving over three years amount to only 1.9 per cent. b. There is no difference between male and femaleas for as the survival duration is concerned. c. Infants have mostly a shorter survival duration, while the middle and old aged persons a longer duration of survival. d. The duration of survival does not seem to change according to the calender year. e. Those surviving from leukemia for longer period tend to die more in winter and less in spring. 3. Mortality and geographical considerations: The district under the present survey is divided into the Sanin, Sanyo, the Shikoku coastal region on the Inland Sea and Shikoku coastal region facing the Pacific Ocean on one hand, and city and country districts on the other. In the absolute number, cases of leukemia are greater in the densely populated coastal regions, especially in the coastal regions facing the Inland Sea. a. The average mortailty per year is 1.39 per 100, 000 population, and the rate is in the descending order of the Sanyo, Sanin, Shikoku coastal region on the Inland Sea and Shikoku coastal region facing the Pacific. As for the city and country districs, the rate is higher in the country district. In looking over the death rate there seems to be a slight correlation between the rate of the technological industrial population and the death rate, but the percentage of farming families and the commercial population percentage have no correlation at all. Likewise as for the mortality in each of the countuies and cities, there seems to be no correlation between the geographical situation and industry. b. From the standpoint of sex there is no difference between the rates in different localities or in urban and rural districts. c. No fixed tendency can be recognized in the age distribution according to different localities, but in comparing the rural district with the urban district, the age distribution is relatively high at the age under 19 years in the former while at the age over 20 years in the latter. d. The duration of survival after the onset of leukemia is shorter in the Sanin District and longer in the Sanyo Disteict; and it is shorter in the rural district and longer in the urban area.