Lymphoma, multiple myeloma and leukaemia incidence in regions of Belarus most heavily contaminated by the Chernobyl accident

There is little information on non-thyroid cancer risks, including haematological malignancies (HM), among the residents of most contaminated regions after the Chernobyl (Chornobyl) nuclear power plant accident. We studied the incidence of lymphoma, multiple myeloma and leukaemia in relation to the raion-average age-specific cumulative absorbed red bone marrow (RBM) dose among the residents of Gomel and Mogilev oblasts in Belarus, which were highly contaminated. The follow-up period was 40 years (1978-2018). HM cases and population size data were received from the Belarusian national cancer registry and the state department of statistics. Our ecological study included 7328 lymphoma, 9476 leukaemia and 2003 multiple myeloma incident cases and 90.8 million person-years in people who were born before the accident and have attained age <80 years old. The mean (median) RBM dose accumulated by December 31, 2018 was 14.2 (6.4) mGy. We found no evidence of increased risks of Hodgkin and non-Hodgkin lymphoma, multiple myeloma or total leukaemia associated with two-year lagged raion-average cumulative RBM dose after adjustment for sex, attained age, urban/rural status and calendar period effects. There was a suggestion of an elevated relative risk of myeloid leukaemia per 100 mGy after exclusion of Gomel and Mogilev cities. Little evidence was found on interaction between selected factors, except sex, and RBM dose for each study outcome. Studies with individually reconstructed cumulative absorbed RBM doses are warranted to provide more insight on dose-effect relationships between HM risk, specifically leukaemia, and protracted environmental exposure at a low dose range.