Between November 2000 and February 2002, five cases of retinoblastoma were diagnosed in children conceived by IVF in the Netherlands, says a report in Jan. 25 issue of The Lancet, and an analysis indicates that the risk of the cancer among IVF children might be five to seven times higher than in children conceived in the usual way.
But the finding "should be treated with caution," says a statement by the European Society of Human Reproduction and Embryology.
"I do agree," adds Dr. Annette C. Moll, an epidemiologist at Vrije Universiteit Medical Center in Amsterdam who is the lead author of the journal report.
Moll says she would tell a couple considering IVF that "the small risk of retinoblastoma is increased, but it still remains a small risk."
IVF is used by couples who cannot have children because of conditions such as blocked fallopian tubes in a woman or very low sperm count in a man. One egg or several eggs are taken from the woman and are fertilized in a laboratory dish. The fertilized eggs are then implanted in the uterus. The success rate for the procedure is about 20 percent.
Retinoblastoma is a cancer of the retina whose usual rate of occurrence is 1 in 20,000. It is easily treated, with a success rate of 90 percent; the affected eye can be saved in four out of five cases. Treatment of all five of the affected children, who were between the ages of 8.5 months and 38 months, was successful, the journal report says.
The European Society of Human Reproduction and Embryology statement quotes Dr. Christina Bergh of Sahlgrenska Hospital in Sweden as saying she has "several concerns about the study."
Three studies published between 1999 and 2000 that included almost 20,000 IVF children found no increase in cancers, the Bergh statement says, and the Scandinavian database shows not a single case of retinoblastoma in 6,000 IVF children.
The Dutch study "is small and bases several figures -- including the percentage of IVF births in the Netherlands -- on assumptions rather than real observations," the Bergh statement says.
An accompanying editorial by Dr. David BenEzra of the pediatric ophthalmology unit at Hadassah Hebrew University in Jerusalem says, "From the many published papers about the incidence of malignancies in large cohorts of children born after assisted reproduction technologies, none has reported the incidence or prevalence of retinoblastoma."
Nevertheless, the editorial adds, "there is little doubt that a heightened awareness and a multidisciplinary approach with a closer follow-up of children conceived with assisted reproduction technologies are needed."
Further studies are needed to confirm that the higher risk exists and to work out any possible cause-and-effect mechanism, Moll says.
"We have contact with IVF-involved doctors to discuss this subject," she adds.