1 / 14

Cancer Risks Following In Utero Exposures

Cancer Risks Following In Utero Exposures. Richard Wakeford. Oxford Survey of Childhood Cancers (OSCC).

marcos
Download Presentation

Cancer Risks Following In Utero Exposures

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Cancer Risks Following In Utero Exposures Richard Wakeford

  2. Oxford Survey of Childhood Cancers (OSCC) • Almost half a century ago Stewart et al. reported the initial results of a case-control study showing a twofold elevation of the risk of leukaemia and other cancer mortality in childhood following an antenatal X-ray examination • Findings were received with scepticism

  3. Relative Risk of Cancer in Childhood Associated with an Obstetric X-ray Examination(Doll and Wakeford, 1997)

  4. Estimates of the Average Fetal Dose per X-ray Film Exposed during an Obstetric Radiographic Examination, 1945-1965

  5. Variation of the ERR of Childhood Cancer Associated with and Obstetric X-ray Examination by Year of Birth, 1940-1976. Data from the Oxford Survey of Childhood Cancers.

  6. OSCC Risk Coefficients • Bithell derived the following coefficients ERR coefficient 51 (95% CI: 28, 76) per Gy EAR coefficient 0.08 (95% CI: 0.04, 0.12) per Gy • Confidence intervals account for statistical errors only

  7. Japanese Atomic Bomb Survivors Exposed In Utero • 753 Japanese children received a dose 10 mSv while in utero (average dose ~300 mSv) • 2 childhood cancers observed against an expected number of ~0.48 • Different background rate presents difficulties for comparison with OSCC

  8. Japanese Atomic Bomb Survivors Exposed In Utero ERR Coefficients • Japanese national rates (Wakeford and Little, 2003) 11 (95% CI: -1, 44) per Sv • Internal comparison group (Delongchamp et al., 1997) 23 (90% CI: 2, 88) per Sv [OSCC ERR coefficient – 51 (95% CI: 28, 76) per Sv]

  9. Some Possible Problems • Cohort study of Court Brown et al. (1960) finds RR of 0.86 (95% CI: 0.41, 1.55) • linkage errors? • Risk of solid tumours proportionally raised to the same extent as leukaemia in OSCC but not after postnatal irradiation • childhood solid tumours principally initiated in utero?

  10. Adult Cancers The experience of the Japanese atomic bomb survivors irradiated in utero indicates that the excess risk of cancer extends into adulthood at a level comparable to that seen among the survivors irradiated as children

  11. Infant Leukaemia • Even for a study as large as the OSCC, data for sub-groups are limited • No indication from the OSCC that the risk of infant leukaemia is particularly raised after irradiation in utero • Great majority of exposures in the OSCC were late in pregnancy for obstetric reasons, so data for relevant exposure period may be limited

  12. Exposure to Radioiron • 634 children in USA exposed in utero to 59Fe • 4 childhood cancers observed against 0.65 expected • Major uncertainties in fetal dose estimates preclude the derivation of reliable risk coefficients

  13. Weapons Testing Fallout • Association between childhood leukaemia and exposure in utero to fallout from nuclear weapons testing not found in • temporal correlation study in the Nordic countries • case-control study in SW Utah • Fetal doses assessed to be <1 mSv • low power to detect effect

  14. Conclusions • Overall, strong evidence that acute fetal doses ~10 mSv increase the risk of cancer in childhood • Risk coefficients from OSCC compatible with those from the Japanese atomic bomb survivors exposed either in utero or (for leukaemia) in childhood.

More Related