[Long-term hematologic changes caused by radioiodine treatment of thyroid cancer. II. Bone marrow changes including leukemia].

59 post-therapeutic examinations of the bone marrow have been performed in 35 patients out of a group of 296 patients treated from 1969 through 1976 by postoperative iodine-131 irradiations for carcinoma of the thyroid gland. Seven patients had normal findings, twelve patients showed panmyelopathy as principal finding, and fourteen patients presented modifications of the three marrow systems in different degrees and combinations. Acute myeloid leukemia was demonstrated in two patients by examination of the bone marrow, in another case the same disease was diagnosed by an analysis of the peripheral blood count. Taking into account the dosimetric considerations of the authors and the three cases of leukemia observed within the total group of patients, a risk factor for leukemia of 7.0 X 10(-5) X rd-1 is calculated which is slightly higher than the leukemia induction rate communicated in literature (22/2646 patients; 1-2/100,000/rd/year).