Study eases childhood cancer survivors’ birth defect worriesby Dagny Stuart Jan. 13, 2012, 1:03 PM
A large, retrospective study of the children of childhood cancer survivors who were treated with radiation therapy and/or some forms of chemotherapy found that the offspring do not have an increased risk for birth defects compared with children of cancer survivors who did not receive these treatments.
The findings provide reassurance that increased risks of birth defects are unlikely for the children of childhood cancers survivors and can help guide family planning choices for those survivors.
The study, led by Vanderbilt-Ingram Cancer Center investigators, was published online last month in the Journal of Clinical Oncology.
“We hope this study will become part of the arsenal of information used by the physicians of childhood cancer survivors if reproductive worries arise,” said lead author Lisa Signorello, associate professor of medicine at Vanderbilt and senior epidemiologist at the International Epidemiology Institute in Rockville, Md.
“Childhood cancer survivors face real reproductive concerns, including unknowns related to the effects of therapy. Hopefully this study will provide some reassurance that their children are unlikely to be at increased risk for genetic defects stemming from their earlier treatment.”
Childhood cancer patients frequently receive aggressive, life-saving radiation and chemotherapy treatments that can affect their ability to have children. Radiotherapy and chemotherapy with alkylating agents can damage DNA.
Previous studies have not determined whether genetic damage from a parent’s treatment could be passed down to their offspring. Genetic-based birth defects are rare in the general population (about 3 percent), and while previous research indicated little or no increased risk for birth defects among the offspring, the studies were relatively small in size and lacked detailed information about radiation and chemotherapy treatments.
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 five-year childhood cancer survivors. The survivors reported their children’s health problems through questionnaires, and investigators also examined medical records, focusing on survivors’ history of radiation to the testes or ovaries and chemotherapy with alkylating agents.
The researchers noted that a strength of the 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. The investigators determined that the prevalence of birth defects among the cancer survivors’ children was similar to what has been reported in the general population.
“The possibility of birth defects in offspring has been a lingering concern among cancer survivors because it’s hard to address,” Signorello said. “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.”