PR of MGUS. (A) By exposure dose in grays adjusting for sex and age at exposure among each exposure category. PR at 1 Gy was 1.06 (95% CI, 0.97-1.16; P = .2) among those aged younger than 20 years at exposure, and 1.01 (95% CI, 0.88-1.16; P = .9) among those aged 20 years and older at exposure. (B) By age at exposure, adjusting for sex and exposure dose among each exposure category. PR for 10-year increase of age was 2.24 (95% CI, 1.39-3.62; P = .001) among those aged younger than 20 years at exposure, and 1.77 (95% CI, 1.03-3.03; P = .04) among those 20 years and older. The dashed line shows 95% CI in each dose.