Abstract
OBJECTIVE: To evaluate the effect of hypothalamic/pituitary radiation (HPT RT) dose on the occurrence of first pregnancy. DESIGN: Retrospective cohort study of childhood cancer 5-year survivors (CCS) diagnosed between 1970 and 1986 before 21 years of age at one of 26 North American pediatric cancer treatment centers. SETTING: Self-administered questionnaire. PATIENT(S): A total of 3,619 female CCS who participated in the Childhood Cancer Survivor Study and received no or scatter (≤0.1 Gy) radiation to the ovaries and 2,081 female siblings (Sibs) of the participants. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Self-reported pregnancy events. RESULT(S): As a group, CCS were as likely to report being pregnant as Sibs (hazard ratio 1.07, 95% confidence interval 0.97-1.19). Multivariable models showed a significant decrease in the risk of pregnancy with HPT RT doses≥22 Gy compared with those CCS receiving no HPT RT. CONCLUSION(S): These results support the hypothesis that exposures of 22-27 Gy HPT RT may be a contributing factor to infertility among female CCS.