The study of monoclonal gammopathy which was detected at atomic bomb health examination

As part of cancer screening for A-bomb survivors, monoclonal gammopathy (M proteinemia) was examined in 52,477 A-bomb survivors from September 1988 through March 1990. This is an analysis of M proteinemia found in 344 A-bomb survivors (0.66%), focusing on transformation into myeloma. The incidence was higher in men (142/296, 0.8%) than women (202/438, 0.58%). According to the classification of M proteinemia, benign monoclonal gammopathy (BMG) was the most common (219 patients, 63.7%), followed by pre-myeloma (pre-MM)(65, 18.9%), myeloma (MM)(54, 15.7%), and macrogloblinemia (MG)(6, 1.7%). There was no correlation between the incidence of M proteinemia and the exposure distance from the hypocenter. IgG type and light chain kappa type were the most predominant (80% and 56%, respectively). M proteinemia increased in frequency with advancing age, especially in the eighth decades of life; the incidence of both BMG and pre-MM became flat after the age of 80 years or older, but MM was still increased. Follow-up of more than 3 years was available in 152 patients after the occurrence of M-spike; 87 patients were followed for more than 5 years and 14 patients for more than 10 years. In a 5 year or more follow-up study of 13 patients with M proteinemia, BMM was found to be transformed into pre-MM or MM in 3 patients and pre-MM into MM in 4 patients. Plasma cells in BMG - in contrast with those in MM - showed no production of IL-6, which acts as an autocrine growth factor of myeloma cells, at either protein or mRNA level. (N.K.)