title: Radiation dose to the pancreas and risk of diabetes mellitus in childhood cancer survivors: a retrospective cohort study.
abstract: BACKGROUND
  Children and young adults treated with total body or abdominal radiotherapy have an increased risk of insulin resistance and diabetes mellitus. However, little is known of the effect of pancreas irradiation on the risk of diabetes. We assessed the relation between radiation exposure and occurrence of diabetes in a large cohort of long-term childhood cancer survivors.
  
  
  METHODS
  We sent a questionnaire to 3468 survivors of a childhood cancer treated in eight centres in France and the UK between 1946 and 1985, of which 2520 were returned. Each self-declaration of diabetes was confirmed by contacting the patients' medical doctors. We estimated the radiation dose received by the tail, head, and body of the pancreas and 185 other anatomical sites during each course of radiotherapy from 1990 to 1995 for each child after reconstruction of the conditions in which irradiation was delivered. We investigated the relation between radiation dose to the pancreas and the risk of a subsequent diabetes diagnosis.
  
  
  RESULTS
  65 cases of diabetes were validated. The risk of diabetes increased strongly with radiation dose to the tail of the pancreas, where the islets of Langerhans are concentrated, up to 20-29 Gy and then reached a plateau for higher radiation doses. The estimated relative risk at 1 Gy was 1·61 (95% CI 1·21-2·68). The radiation dose to the other parts of the pancreas did not have a significant effect. Compared with patients who did not receive radiotherapy, the relative risk of diabetes was 11·5 (95% CI 3·9-34·0) in patients who received 10 Gy or more to the tail of the pancreas. Results were unchanged after adjustment for body-mass index, despite its strong independent effect (p<0·0001), and were similar between men and women. Children younger than 2 years at time of radiotherapy were more sensitive to radiation than were older patients (relative risk at 1 Gy 2·1 [95% CI 1·4-4·3] vs 1·4 [95% CI 1·1-2·2] in older patients; p=0·02 for the difference). For the 511 patients who had received more than 10 Gy to the tail of the pancreas, the cumulative incidence of diabetes was 16% (95% CI 11-24).
  
  
  CONCLUSIONS
  Our study provides evidence of a dose-response relation between radiation exposure of pancreas and subsequent risk of diabetes. Because of the risks observed and the frequency of diabetes in general population, this finding raises important public health issues. The pancreas needs to be regarded as a critical organ when planning radiation therapy, particularly in children. Follow-up of patients who received abdominal irradiation should include diabetes screening.
authors.affiliation: Radiation Epidemiology Group, INSERM U1018, Villejuif, France; Institut Gustave Roussy, Villejuif, France; Université Paris-Sud, Villejuif, France. florent.devathaire@igr.fr
authors.forename: Florent
authors.initials: F
authors.lastname: de Vathaire
authors.forename: Chiraz
authors.initials: C
authors.lastname: El-Fayech
authors.forename: Faten Fedhila
authors.initials: FF
authors.lastname: Ben Ayed
authors.forename: Nadia
authors.initials: N
authors.lastname: Haddy
authors.forename: Catherine
authors.initials: C
authors.lastname: Guibout
authors.forename: David
authors.initials: D
authors.lastname: Winter
authors.forename: Cécile
authors.initials: C
authors.lastname: Thomas-Teinturier
authors.forename: Cristina
authors.initials: C
authors.lastname: Veres
authors.forename: Angela
authors.initials: A
authors.lastname: Jackson
authors.forename: Hélène
authors.initials: H
authors.lastname: Pacquement
authors.forename: Martin
authors.initials: M
authors.lastname: Schlumberger
authors.forename: Mike
authors.initials: M
authors.lastname: Hawkins
authors.forename: Ibrahima
authors.initials: I
authors.lastname: Diallo
authors.forename: Odile
authors.initials: O
authors.lastname: Oberlin
mesh_terms: D000293:Adolescent; D015992:Body Mass Index; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D003920:Diabetes Mellitus / Q000209:etiology*; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D009369:Neoplasms / Q000532:radiotherapy*; D010179:Pancreas / Q000528:radiation effects*; D011829:Radiation Dosage; D012189:Retrospective Studies; D012306:Risk; D017741:Survivors