Survivors of childhood cancer run particular risks when pregnant and should be closely monitored, say researchers.
It was reported at the 25th annual conference of the European Society of Human Reproduction and Embryology, (Wednesday 1 July). Dr. Sharon Lie Fong, of the Department of Obstetrics and Gynaecology, Erasmus MC University Medical Center, Rotterdam, The Netherlands, said that, although such women may have conceived spontaneously and considered themselves to be perfectly healthy, their deliveries should always take place in a hospital.
Dr. Lie Fong and colleagues studied data on the pregnancies of 40 women who had been treated for cancer during their childhood, the majority of them for leukemia, but also for solid tumors. Six had had radiation treatment directly to the abdomen. The data were compared with those from a control group of more than 9,000 women who had not had cancer treatment. All data were obtained from The Netherlands Perinatal Register, a nationwide database of pregnancy outcomes. Data were matched for age at pregnancy, year and month of delivery, and the number of times the woman had given birth.
The team did not investigate overall fertility and miscarriage rates, but they believe that it is possible that the fertility of all the cancer survivors may be compromised. "We know that radiotherapy and some chemotherapy treatments are toxic to the ovarian follicles," said Dr. Lie Fong, "and, in an earlier study, we had already found that ovarian reserve is smaller in adult survivors of childhood cancer than in age-matched controls."
The ovarian reserve, or capacity of the ovary to provide eggs capable of fertilization, is established in the fetus and decreases during a woman's reproductive lifetime. Women with a poor ovarian reserve are less likely to conceive, even with assisted reproduction therapies, than those with a normal number of eggs. They may also have an earlier menopause, as their stock of eggs is exhausted at a younger age.
Long-term, multi-disciplinary follow-up for female child cancer survivors is mandatory, the researchers say. Although at the start of treatment, future fertility may not be of great concern to care providers, it is to the patient's parents. And during follow-up, survivors should be made aware of the possible late effects of their treatment.
In addition to the deleterious effects of abdominal radiotherapy on reproductive function, radiotherapy to the head can also cause problems by causing the hypothalamus to reduce the production of follicle stimulating hormone and luteinizing hormone, both important in promoting ovulation. "We believe that it is particularly important for all female children who are treated for cancer, and their parents, to be made aware of this risk. Our research has also shown how important it is that, if they do become pregnant, childhood cancer survivors should be closely monitored throughout their pregnancy and that they are delivered in a clinical setting, rather than at home."
The researchers say that even if at first fertility seems normal for childhood cancer survivors, there may be problems later in life. "We have yet to see whether the effects of cancer treatment include an earlier menopause," said Dr. Lie Fong, "and this possibility should be borne in mind when counselling these women on their reproductive options."