title: Ionizing radiation exposures in treatments of solid neoplasms are not associated with subsequent increased risks of chronic lymphocytic leukemia.
abstract: Exposure to ionizing radiation is not thought to cause chronic lymphocytic leukemia (CLL). Challenging this notion are recent data suggesting CLL incidence may be increased by radiation exposure from the atomic bombs (after many decades), uranium mining and nuclear power facility accidents. To assess the effects of therapeutic ionizing radiation for the treatment of solid neoplasms we studied CLL risks in data from the Surveillance, Epidemiology, and End Results (SEER) Program. Specifically, we compared the risks of developing CLL in persons with a 1(st) non-hematologic cancer treated with or without ionizing radiation. We controlled for early detection effects on CLL risk induced by surveillance after 1(st) cancer diagnoses by forming all-time cumulative CLL relative risks (RR). We estimate such CLL RR to be 1.20 (95% confidence interval, 1.17, 1.23) for persons whose 1(st) cancer was not treated with ionizing radiation and 1.00 (0.96, 1.05) for persons whose 1(st) cancer was treated with ionizing radiations. These results imply that diagnosis of a solid neoplasm is associated with an increased risk of developing CLL only in persons whose 1(st) cancer was not treated with radiation therapy.
authors.affiliation: Department of Quantitative Health Sciences, Cleveland Clinic Lerner Research Institute, Cleveland, OH, United States. Electronic address: radivot@ccf.org.
authors.forename: Tomas
authors.initials: T
authors.lastname: Radivoyevitch
authors.affiliation: Department of Mathematics, University of California, Berkeley, CA, United States.
authors.forename: Rainer K
authors.initials: RK
authors.lastname: Sachs
authors.affiliation: Haematology Research Centre, Division of Experimental Medicine, Department of Medicine, Imperial College London, London, UK.
authors.forename: Robert Peter
authors.initials: RP
authors.lastname: Gale
authors.affiliation: Department of Hematology and Medical Oncology, Cleveland Clinic Taussig Cancer Institute, OH, United States.
authors.forename: Mitchell R
authors.initials: MR
authors.lastname: Smith
authors.affiliation: Department of Hematology and Medical Oncology, Cleveland Clinic Taussig Cancer Institute, OH, United States.
authors.forename: Brian T
authors.initials: BT
authors.lastname: Hill
mesh_terms: D005260:Female; D006801:Humans; D015451:Leukemia, Lymphocytic, Chronic, B-Cell / Q000453:epidemiology / Q000209:etiology; D008297:Male; D009381:Neoplasms, Radiation-Induced / Q000453:epidemiology*; D011839:Radiation, Ionizing; D011878:Radiotherapy / Q000009:adverse effects*; D012307:Risk Factors; D018426:SEER Program
keywords: 2(nd) cancer risks; Chronic lymphocytic leukemia; Ionizing radiation; SEER