A cohort of 94,000 survivors of the Hiroshima and Nagasaki atomic bombings is being studied in collaboration with the Radiation Effects Research Foundation. Cohort studies are used to quantify radiation dose response and its dependence on histological subtype of tumor, age at exposure, sex, age at observation, and time following exposure. Recent achievements include an extension of an earlier assessment of hematopoietic and lymphoproliferative malignancies75 with 16 years of additional follow-up that revealed a generally declining excess risk of leukemia with time and with increasing age, although elevated risks persisted 55 years after exposure that differed by leukemia sub-types. Similarly, evaluation of long-term trends of thyroid cancer demonstrated that the excess risk decreased with time or increasing age while remaining significantly elevated 60 years after exposure among those exposed in childhood or adolescence. About 30% of the lung cancer cases in this cohort were attributable to smoking while about 7% were attributed to radiation. Radiation interacted with smoking super-multiplicatively for light/moderate smokers and additively or sub-additively for heavy smokers. Following two landmark publications of comprehensive analyses of LSS solid cancer incidence data, a new large-scale effort is in progress to update solid cancer incidence data through 2009.