Retrospective Survey on Medical Irradiation and Leukemogenesis in Japan

Survey cards were distributed to the leukemic patients in the departments of internal medicine and pediatrics of hospitals in Japan from 1961 to 1965, with requests for the name, sex, type and date of onset of disease, and type and frequency of prior medical irradiation. Of 1, 197 available cards collected, 49 or 4.09 per cent had a history of fluoroscopic examination and 19 or 1.59 per cent had a history of prior therapeutic irradiation. On the other hand, out of 2, 609 controls selected randomly from patients with non-malignant diseases or healthy persons, 146 or 5.60 per cent had a history of fluoroscopic examination and 13 or 0.50 per cent had a history of radiotherapy. Namely, the fluoroscopic irradiation rate was slightly higher in controls than in leukemic patients, although there was no statistically significant difference. Whereas, the therapeutic irradiation rate was significantly higher in leukemic patients than in controls. Next, the integral bone marrow dose received during fluoroscopy or radiotherapy was calculated, based on Miyakawa and Hashizume's data. The average bone marrow dose was estimated to be 2, 704 grads in leukemic patients and 762 grads in controls. Results of this survey indicated that prior radiotherapy could be related to leukemogenesis.