The medical speciality in which there is statistically higher incidence of leukemia:

Radiation causes cancer by modifying DNA. The most likely mechanism is a multistep process including accumulation of radiation-induced gene mutation. These mutations are usually base substitutions, insertions and deletions of bases, rearrangements caused by breakage and abnormal rejoining of DNA strands, or changes in the copy number of DNA segments. When the mutations involve growth-regulating genes—activation of oncogenes or inactivation of tumor suppressor genes—they can deregulate cell growth or differentiation or both and ultimately lead to neoplastic development. In principle, even one radiation photon may initiate cancer formation.