COMMENTARY

Researchers Dissect Link Between Fertility Treatment and Childhood Cancer

Peter Kovacs, MD, PhD

Disclosures

October 02, 2013

Fertility Treatment and Childhood Cancer Risk: A Systematic Meta-analysis

Hargreave M, Jensen A, Toender A, Andersen KK, Kjaer SK
Fertil Steril. 2013;100:150-161

Background

Controlled ovarian stimulation has been available since the 1960s and in vitro fertilization (IVF) since the late 1970s. It is estimated that 4-5 million children have been born following IVF. In developed countries, up to 5% of children born are conceived through IVF.[1]

Since assisted reproductive technology (ART) was introduced, its safety has been questioned and tested. There are immediate risks that are associated with the intervention itself, such as ovarian hyperstimulation; bladder, bowel, and blood vessel injury during retrieval; infections related to the vaginal procedures; and an increased risk for thrombosis.

Numerous studies have evaluated the long-term risks associated with hormone use itself. Most have been reassuring and have found no additional adverse effects with the use of hormones, though infertility itself is a known risk factor for certain gynecologic cancers.

The risk for birth defects following assisted reproduction has also been studied by several groups. While an overall increased risk was seen in ART pregnancies, it is believed that this excess is associated with infertility and the underlying problems rather than the treatment itself.[2]

Risk for cancer in the offspring conceived through ART is much less studied. In 2005, a meta-analysis found no increased risk for childhood cancer in children conceived via IVF.[3]

This study is another analysis based on the results of reports published before and after 2005.

Study Summary

Twenty-five studies were included in the analysis. They are all cohort or case-control studies that assessed the association between medically assisted reproduction (stimulation only, insemination, or IVF) and childhood cancer risk. Overall, an increased risk for cancer was seen among those exposed to ART (relative risk [RR], 1.33; 95% confidence interval [CI], 1.08-1.63). When cancer subtypes were evaluated separately, an increased risk was found for hematologic cancers (RR, 1.59; 95% CI, 1.232-1.91) and central nervous system cancers (RR, 1.88; 95% CI, 1.02-3.46). The risk for neuroblastoma, retinoblastoma, and other solid cancers was also higher among those exposed to ART, though the association was based on a small number of cancers.

In their concluding remarks, the authors discussed that while the relative risks show an increased risk, the absolute number of additional cancers is very low. They also mentioned that at this point it is unknown whether the increased risk is associated with infertility or with the technology used to treat it.

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