Women who had survived childhood cancer were nearly 50% more likely to experience clinical infertility (more than one year of unsuccessful attempts at conception) than were their siblings, according to findings from the Childhood Cancer Survivor Study (CCSS). However, the majority of these women did eventually become pregnant.

Although previous research has shown decreased pregnancy rates and early menopause in female cancer survivors, infertility rates and reproductive interventions have not been studied, wrote a team led by Sara E. Barton, MD, of Brigham and Women’s Hospital in Boston, Massachusetts, in The Lancet Oncology. Most other studies of infertility in women who had survived cancer centered on increased rates of early menopause or ovarian failure. Barton and colleagues, however, concentrated their analysis on women who were trying to conceive.

The investigators gathered demographic, medical, and reproductive data as well as information on exposure to alkylating agents and radiation therapy for 3,531 survivors and 1,366 female sibling controls enrolled in the CCSS between November 1992 and April 2004.

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The CCSS is a cohort study that includes 5-year cancer survivors from 26 US and Canadian institutions who were younger than age 21 years at the time of cancer diagnosis and who received their diagnosis from January 1970 through December 1986. Barton and colleagues focused on women aged 18 to 39 years who had ever been sexually active.

Compared with their siblings, survivors were 48% more likely to experience clinical infertility. This was most pronounced at early reproductive ages: Infertility was nearly three times more common in survivors than in siblings in women younger than age 24 years, the youngest group studied. Far less of a gap was seen between survivors and siblings in their late 30s, likely because infertility is more common in all women at that age, regardless of cancer history.

Despite the fact that survivors had increased time to pregnancy compared with their siblings, 292 (64%) of the 455 participants with self-reported clinical infertility did ultimately become pregnant. This is similar to the rate recorded in surveys of all infertile women.

Survivors and siblings were equally likely to seek treatment for infertility, but survivors were less likely to be prescribed drug therapy for the problem. Increasing doses of uterine radiation and alkylating-agent chemotherapy were strongly associated with infertility.