Radiation-induced myelomatosis.

It is well known that radiation can cause myeloid leukemia. However, no excess of chronic lymphocytic leukemia has been observed. Myelomatosis, like chronic lymphocytic leukemia, is a tumor of B lymphocytes. To determine whether this disease has a radiogenic origin, we surveyed all cohorts of persons exposed to radiation for which data on cancer-related mortality are available. An excess of myeloma was found in most cohorts. However, a striking deficit was found in two groups irradiated intensely for uterine neoplasms (three cases observed, 10.71 expected; P = 0.012). All other groups combined had a highly significant excess (50 observed, 22.21 expected; P = 2 X 10(-7)). The largest relative risk appeared among persons receiving internal doses of alpha-particles (14 observed, 3.24 expected; P = 2 X 10(-5)), but a significant excess (13 observed, 6.33 expected; P = 0.026) was also found in patients receiving only therapeutic or diagnostic gamma-rays or x-rays. Most cases occurred 15 to 25 years after exposure.