title: Radiotherapy and subsequent thyroid cancer in German childhood cancer survivors: a nested case-control study.
abstract: BACKGROUND
  Radiotherapy is associated with a risk of subsequent neoplasms (SN) in childhood cancer survivors. It has been shown that children's thyroid glands are especially susceptible. The aim is to quantify the risk of a second neck neoplasm after primary cancer radiotherapy with emphasis on thyroid cancer.
  
  
  METHODS
  We performed a nested case-control study: 29 individuals, diagnosed with a solid SN in the neck region, including 17 with thyroid cancer, in 1980-2002 and 57 matched controls with single neoplasms were selected from the database of the German Childhood Cancer Registry. We investigated the risk associated with radiotherapy exposure given per body region, adjusted for chemotherapy.
  
  
  RESULTS
  16/17 (94.1 %) thyroid SN cases, 9/12 (75 %) other neck SN cases and 34/57 (59.6 %) controls received radiotherapy, with median doses of 27.8, 25 and 24 Gy, respectively. Radiotherapy exposure to the neck region increased the risk of the other neck SNs by 4.2 % (OR = 1.042/Gy (95 %-CI 0.980-1.109)) and of thyroid SN by 5.1 % (OR = 1.051/Gy (95 %-CI 0.984-1.123)), and radiotherapy to the neck or spine region increased the thyroid risk by 6.6 % (OR = 1.066/Gy (95 %-CI 1.010-1.125)). Chemotherapy was not a confounder. Exposure to other body regions was not associated with increased risk.
  
  
  CONCLUSIONS
  Radiotherapy in the neck or spine region increases the risk of thyroid cancer, while neck exposure increases the risk of any other solid SN to a similar extent. Other studies showed a decreasing risk of subsequent thyroid cancer for very high doses; we cannot confirm this.
authors.affiliation: German Childhood Cancer Registry, Institute of Medical Biostatistics, Epidemiology and Informatics, University Medical Centre of the Johannes Gutenberg University Mainz, Mainz, 55101, Germany.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Finke
authors.affiliation: Institute of Medical Biostatistics, Epidemiology and Informatics, University Medical Centre of the Johannes Gutenberg University Mainz, Mainz, 55101, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Scholz-Kreisel
authors.affiliation: University Childrens' Hospital Essen, Pediatric Haematology and Oncology, Essen, 45147, Germany.
authors.forename: Ulrike
authors.initials: U
authors.lastname: Hennewig
authors.affiliation: Institute of Medical Biostatistics, Epidemiology and Informatics, University Medical Centre of the Johannes Gutenberg University Mainz, Mainz, 55101, Germany.
authors.forename: Maria
authors.initials: M
authors.lastname: Blettner
authors.affiliation: German Childhood Cancer Registry, Institute of Medical Biostatistics, Epidemiology and Informatics, University Medical Centre of the Johannes Gutenberg University Mainz, Mainz, 55101, Germany. clauspix@uni-mainz.de.
authors.forename: Claudia
authors.initials: C
authors.lastname: Spix
mesh_terms: D000230:Adenocarcinoma / Q000453:epidemiology*; D000293:Adolescent; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D005260:Female; D005354:Fibrosarcoma / Q000453:epidemiology; D005858:Germany; D006689:Hodgkin Disease / Q000453:epidemiology; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D009333:Neck / Q000528:radiation effects; D009369:Neoplasms / Q000532:radiotherapy*; D009381:Neoplasms, Radiation-Induced / Q000453:epidemiology*; D011879:Radiotherapy Dosage; D012042:Registries; D012509:Sarcoma / Q000453:epidemiology; D017741:Survivors; D013964:Thyroid Neoplasms / Q000453:epidemiology*; D055815:Young Adult