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Child cancer survivors can become pregnant as adults

70% of female cancer survivors in study became pregnant

Adrain O'Dowd

Wednesday, 23 March 2016

Women who survive cancer as a child stand a good chance of becoming pregnant but men’s chances of becoming a father are smaller, according to one of the largest studies of its kind published today in The Lancet Oncology.*

The majority (80%) of children with cancer live into adulthood so their ability to become a parent is a major concern for them.

Growing awareness of the adverse effects of radiotherapy has led to the use of more intensive chemotherapy regimens for the treatment of childhood cancers and previous research has shown that fertility can be compromised by several types of chemotherapy, mainly alkylating drugs.

However, little is known about the dose effects on pregnancy from newer drugs, such as ifosfamide and cisplatin, in survivors of childhood cancer.

Therefore, Dr Eric Chow from the Fred Hutchinson Cancer Research Center, Seattle, USA and colleagues used data from the Childhood Cancer Survivor Study (CCSS) to investigate the effects of these drugs on pregnancy in male and female survivors.

The CCSS tracks people who were diagnosed with the most common types of childhood cancer before the age of 21 and treated at 27 institutions across the USA and Canada between 1970 and 1999, and who had survived at least 5 years after diagnosis.

In the new study, the researchers examined the impact of various doses of 14 commonly used chemotherapy drugs on pregnancy and livebirth in 10,938 male and female survivors, compared with 3,949 siblings.

The study focused on survivors treated with chemotherapy and who did not receive any radiotherapy to the pelvis or the brain.

Results showed that by the age of 45, 70% of female cancer survivors became pregnant, compared to over 80% of siblings. For male cancer survivors, the figure was 50% compared to 80% for siblings.

The male survivors of childhood cancer were significantly less likely to have children, especially if they had been treated with chemotherapy regimens containing high doses of commonly used alkylating drugs and cisplatin.

The findings were consistent with previous studies that have suggested that men who have undergone cancer treatment with these drugs have lower sperm count and reduced testicular volume.

In female survivors, only busulfan and high doses of lomustine were directly linked with lower likelihood of pregnancy.

Overall, female survivors were still less likely to conceive compared to siblings but the effect was much smaller compared to men.

However, in women, the difference was more pronounced for those who delayed pregnancy until they were aged 30 or older, possibly because chemotherapy exposure might accelerate the natural depletion of eggs and hasten menopause.

The authors said their study relied on self-reported pregnancy and livebirth, and did not account for other factors such as marital or cohabitation status, the intention to conceive or length of time attempting to conceive.

They acknowledge that while the total number of survivors in the study was large, the number of patients who were exposed to individual drugs varied significantly, so more research was needed to estimate the exact risk of some less commonly used drugs.

Dr Chow said: “We think these results will be encouraging for most women who were treated with chemotherapy in childhood.

“However, I think, we, as paediatric oncologists, still need to do a better job discussing fertility and fertility preservation options with patients and families upfront before starting cancer treatment.”

* Chow EJ, et al. Pregnancy after chemotherapy in male and female survivors of childhood cancer treated between 1970 and 1999: a report from the Childhood Cancer Survivor Study cohort. The Lancet Oncology, March 2016. DOI: 10.1016/S1470-2045(16)00086-3

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