A large, retrospective study shows that children of childhood cancer survivors who received prior treatment involving radiation to testes or ovaries and chemotherapy with alkylating agents do not have an increased risk for birth defects compared to children of survivors who did not have such cancer treatment.
The findings provide reassurance that increased risks of birth defects are unlikely for cancer survivors who are concerned about the potential effects of their treatment on their children, and can help guide family planning choices.
“We hope this study will become part of the arsenal of information used by the physicians of childhood cancer survivors if reproductive worries arise.” – Lisa Signorello Sc.D. associate professor of medicine Vanderbilt University i
According to Signorello, childhood cancer patients frequently receive aggressive, though life-saving, radiation and chemotherapy treatments that can affect their ability to have children. For girls, radiation to the pelvis – and the resulting damage to the uterus – has been associated with a risk for pregnancy outcomes such as miscarriage and preterm birth, and effects on the ovaries can lead to infertility.
Genetic-based birth defects are rare in the general population (about 3 percent), and while previous research results indicated little or no increased risk for birth defects among the offspring of cancer survivors, such studies were relatively small in size and lacked detailed information about radiation and chemotherapy treatments, such as specific radiation doses to the testes and ovaries.
In the current study, investigators used information from the Childhood Cancer Survivor Study, a large retrospective study of treatment and outcomes in more than 20,000 childhood cancer survivors diagnosed between 1970 and 1986. Signorello and her colleagues examined data from 4,699 children of 1,128 men and 1,627 women who were 5-year childhood cancer survivors.
Of the survivors, 63 percent (1,736) had received radiation for their cancer as children, and 44 percent of men (496) and 50 percent of women (810) had received chemotherapy with alkylating agents. Overall, 2.7 percent (129) of the survivors’ children had at least one birth defect, such as Down syndrome, achondroplasia or cleft lip.
The researchers also noted that a strength of their study is the comparison they made to the children of other cancer survivors and not to the children of people randomly sampled from the general population. Signorello said that comparing cancer survivors to individuals in the general population can be difficult because the latter may not be as thorough in reporting health problems of their children, and the children of cancer survivors may be under heightened clinical surveillance and may appear to have higher rates of birth defects as a result.
“The possibility of birth defects in offspring has been a lingering concern among cancer survivors because it’s hard to address,” Signorello said.
“We know these are rare outcomes, and a large study group was needed to address these questions. It took years to validate the parents’ self-reported outcomes, and to assemble and use the medical records of radiation and chemotherapy treatment exposures to allow us to quantify their exposure doses. These are the strongest results to date, adding greater certainty to other studies examining this common concern among survivors of childhood cancer,” she stated.
The researchers would like to continue to sequence the DNA of families of childhood cancer survivors (survivors and their children) to see if there is any evidence of radiation- or chemical-induced genetic damage, even if the children did not have birth defects. They would also like to combine data from all U.S. and international studies on this topic in order to provide even larger, more definitive results.