Spontaneous abortion in a Danish population-based cohort of childhood cancer survivors.
OBJECTIVE
Radiation induces germ-cell mutations in experimental animals that result in adverse pregnancy outcomes, as does uterine damage caused by high-dose radiotherapy. We assessed the risks for spontaneous abortion and stillbirths among cancer survivors who received radiotherapy and subsequently became pregnant.


METHODS
We identified 1,688 female survivors of childhood cancer in the Danish Cancer Registry. Radiation doses to the ovary and uterus were characterized as high to low. The pregnancy outcomes of survivors, 2,737 sisters, and 16,700 comparison women in the population were identified from nationwide registries. The proportions of pregnancies among survivors that resulted in a livebirth, stillbirth, or abortion were compared with the equivalent proportions among the two comparison groups, and proportion ratios (PRs) were computed with sisters as referent.


RESULTS
More than 34,000 pregnancies were evaluated, 1,479 of which were among cancer survivors. No significant differences were seen between survivors and comparison women in the proportions of livebirths, stillbirths, or all types of abortions combined. Survivors, however, had a 23% excess risk for spontaneous abortion (PR, 1.23; 95% CI, 1.0 to 1.5), related primarily to prior radiation treatments (PR, 1.58; 95% CI, 1.2 to 2.2) and especially high-dose radiotherapy to the ovaries and uterus (PR, 2.8; 95% CI, 1.7 to 4.7).


CONCLUSIONS
The pregnancy outcomes of survivors were similar to those of comparison women. A slight excess risk for spontaneous abortion may have resulted from uterine damage after high-dose pelvic radiotherapy, consistent with previous studies, although radiation-induced germinal mutations or decreased hypothalamic-pituitary-ovarian function could not be ruled out.
Winther
Jeanette F
JF
Institute of Cancer Epidemiology, Danish Cancer Society, Strandboulevarden 49, DK-2100 Copenhagen, Denmark; jeanette@cancer.dk.
Boice
John D
JD
Svendsen
Anne Louise
AL
Frederiksen
Kirsten
K
Stovall
Marilyn
M
Olsen
Jørgen H
JH
D000022:Abortion, Spontaneous / Q000453:epidemiology*; D015331:Cohort Studies; D003718:Denmark / Q000453:epidemiology; D005260:Female; D006801:Humans; D009369:Neoplasms / Q000532:radiotherapy*; D009381:Neoplasms, Radiation-Induced / Q000453:epidemiology*; D010053:Ovary / Q000528:radiation effects; D010388:Pelvis / Q000528:radiation effects; D011247:Pregnancy; D011256:Pregnancy Outcome; D017741:Survivors; D014599:Uterus / Q000528:radiation effects
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