Stillbirth more likely in female childhood cancer survivors
Lisa Signorello, Sc.D.
John Boice Jr., Sc.D.
Vanderbilt-Ingram Cancer Center
The study led by John Boice Jr., Sc.D., professor of Medicine, and Lisa Signorello, Sc.D., associate professor of Medicine, appeared online and will be published in an upcoming issue of Lancet. Boice and Signorello are members of the International Epidemiology Institute, Rockville, Md.
The authors used data from the Childhood Cancer Survivor Study (CCSS), from 25 U.S. institutions and one in Canada. All of the patients in CCSS were younger than 21 at the time of initial diagnosis of cancer and had survived for at least five years after diagnosis.
Among the 1,148 men and 1,657 women who had survived childhood cancer, there were 4,946 pregnancies. Women who had received the highest doses of uterine and ovarian irradiation during their previous cancer therapy were far more likely (up to 12 times) to experience a stillbirth or death of their baby. For girls treated before puberty, even lower radiation doses (1.0-2.5 Gy) were linked to an increased risk (up to five times) of stillbirth or neonatal death.
However, men who had received radiation of the testes and women whose pituitary glands were irradiated did not experience abnormal rates of stillbirth or neonatal death. The use of alkylating chemotherapy drugs in both sexes also was not associated with an increased risk.
The study of health risks for the offspring of cancer survivors is significant because advances in cancer management have led to a sharp increase in the number of childhood cancer survivors who reach adulthood and want to have children.
“High-dose pelvic irradiation can permanently impair growth and blood flow to the uterus and results in a reduced uterine volume, and these effects of radiation are likely to be dependent on age,” the authors say. “Whether these types of effects on the uterus increase the risk of placental or umbilical-cord anomalies or other factors already linked to stillbirth, or whether they operate through different mechanisms needs clarification.”
The authors conclude, “For men exposed to gonadal irradiation, there does not seem to be an increased risk of stillbirth or neonatal death among their offspring, which is reassuring not only for male survivors of childhood cancer but also for men exposed to ionizing radiation in occupational or other settings. For women, however, high-dose uterine or ovarian radiation does seem to have important adverse effects, which are mostly likely due to uterine damage. Therefore, careful management is warranted for pregnant women treated with high doses of pelvic irradiation before they have reached puberty.”