Prevalence and Cause of Death in Patients with Monoclonal Gammopathy in Atomic Bomb Survivors in Hiroshima

Purpose: To examine the effect of Atomic bomb (A-bomb) radiation exposure condition on the development M-proteinemia in A-bomb survivors in Hiroshima.

Back ground: The influence of radiation exposure on the development of M-proteinemia remained unclear. The screening test for monoclonal gammopathy in A- bomb survivors in Hiroshima was started from Sep. 1988 at the Hiroshima Atomic Bomb Casualty Council Health management center to challenge this problem with the free access policy.

Materials: The peak year of the examined population was 1989, which was examined 42915 survivors. This population was designed as study population. This population consisted of five groups of irradiated conditions as follows, 60% was exposed directly in all over the Hiroshima city at A- bombing, 27% entered to center of Hiroshima city within 14 days after A-bombing, 9% helped the victims of A- bombing at the suburbs and 1% was exposed in prenatal state.

Examination study: Each participant was examined one test yearly. Routine laboratory tests, such as complete blood cell counts, serum biochemical examination and serum protein electrophoresis on cellulose acetate were performed for the first step screening. M-protein or low level of gammaglobulin was subsequently assessed in a detailed analysis by immunoelectrophoresis of serum and urine, and measurement of serum concentration of immunoglobulin andβ2-Microglobulin.

Results: One thousand and hundred eighty two cases of M-proteinemia were detected for 18 years. The over all prevalence rate was 2.75%, and 4.1% in males and 2.1% in females. Nine hundred twenty nigh cases of MGUS(78.6%), 147 cases of MM(12.4%), 80 cases of IgM Macroglobulinemia(6.8%) and 26 cases of two clone M-proteinemia(2.2%) were detected. Of these M-proteinemia, 669cases(2.6%) were developed in directly exposed population, 368cases(3.1%) were in entered population and 133 cases(3.4%) were in helper population. The prevalence rate of these M-proteinemia was increased depend on aging. Forty three cases (4.6%) of MGUS moved to overt MM for 18 years. The mean duration time from MGUS to overt MM was 8.9 years (2~18 years). Four hundred sixteen cases (35.2%) were died with MM or lymphoproliferative diseases (99cases,23.8%), cancer (93cases,22.3%), infection (50cases,12%), cardio or cerebral vascular diseases (89 cases,21.4%) and others (85cases,21%). The 101 cases (13.2%) of 766 living cases combined some cancer throughout the follow up. No significant differences in the prevalence rate of M-proteinemia and death from MM or combination with cancer were observed among any A-bomb irradiated conditions.

Conclusions: There were no clear correlations between the development or disease state of M-proteinemia and the irradiated conditions. We are now starting to analyze the individual radiation dose effects longitudinally on the development of M-proteinemia.