Epidemiological inference on induction of aplastic anemia following radiotherapy

Some epidemiological inferences on possibility of induction of aplastic anemia following radiotherapy are tried. In Japan after 1969, there are detected and reported 11 cases of radiation-related aplastic anemia after radiotherapy diagnosed by hematologists. Of 11 cases, 2 are males and 9 are females, ranging 28 to 66 years of age. All these patients were irradiated for malignant diseases. The population at risk after 1969 was estimated to be 674, 660 man-years, based on the additional survey on number and survival rate of patients irradiated. The expected value of aplastic anemia calculated from this population at risk is 10.2, against 11 cases observed above-described. There is no statistically significant difference. Namely, there is no epidemiological evidence that aplastic anemia is induced by local-body irradiation such as radiotherapy. (auth.)