Frozen embryo transfer slightly increases childhood cancer risk

Marie Hargreave

The use of frozen embryo transfer in women was linked to a small but statistically significant increased risk for childhood cancer compared with children born to fertile women, according to recent findings.

“We previously showed an association between fertility treatment and childhood cancer risk,” Marie Hargreave, PhD, senior researcher at the Danish Cancer Society Research Center in Copenhagen, Denmark, told Healio Primary Care. “However, it was unclear whether the increased risk was associated with the underlying infertility of the couples, the fertility drugs used, or use of specific assisted reproduction technologies.”

Hargreave and colleagues analyzed the risk for childhood cancer based on specific maternal fertility treatments, including the use of fertility drugs — like clomiphene, gonadotropins, gonadotropin-releasing hormone analogs, human chorionic gonadotropin, progesterone and estrogen — as well as in vitro fertilization, intracytoplasmic sperm injection and frozen embryo transfer. Their analysis included more than 1 million children born in Denmark between Jan. 1, 1996, and Dec. 31, 2012.

They found that only the use of frozen embryo transfer was tied to an elevated risk for childhood cancer (HR = 2.43 [95% CI, 1.44-4.11]; incidence rate difference = 26.9 per 100,000 [95% CI, 2.8-51]) compared with children born to fertile women. The higher risk was mainly due to an increased risk for leukemia and sympathetic nervous system tumors, according to researchers.

Hargreave explained that “frozen embryo transfer differs from other types of treatment both in the use of fertility drugs, use of cryoprotectants and the freezing and thawing of embryos.”She said more “large-scale, high quality studies have to be conducted to confirm our findings. Even if our findings should be true, it is important to stress the fact that the increased risk is very small.” – by Janel Miller

Disclosures: The authors report no relevant financial disclosures.