By Lisa Rapaport
(Reuters Health) – Some rare childhood cancers may be more common in children created by in vitro fertilization (IVF), a US study suggests, but parents do not need to lose sleep over this perception. , according to the researchers.
"For the few cancers that appeared to be associated with IVF the absolute risk was still very rare," said the author of the study Logan Spector of the University of Minnesota at Minneapolis.
The increased risk of cancer can be partly responsible for at least the age of the mother and other health factors leading women to try IVF in the first place, Spector's note and colleagues in JAMA Pediatrics. Although the results suggest that it can make sense to be vigilant when monitoring IVF children for cancer, they do not mean that couples should not try to conceive like this, Spector says by e-mail.
"There was no indication that any specific IVF treatment or treatment was associated with these cancers, so there is nothing that patients or their providers should be doing differently," added Spector. "In general, these results should be encouraging for parents who have used IVF."
The Spector team examined data on 275,686 children produced with IVF and 2.27 million children created naturally from 2004 to 2013.
They tracked children for an average of four and a half years, during which 321 cancers were detected by IVF children and 2,042 cancers were detected among other children. That equates to a rate of 0.1 per cent among IVF children and 0.09 per cent among children who have created their natural.
In another way, if researchers traced a million children for a year, they would expect to see one of these rare cancers develop in around 252 children conceived by IVF and about 193 naturally born children. .
In particular, children conceived using IVF were 28 per cent more likely than other children to be diagnosed with embryonic tumors, developing from embryonic cells that remain in the body after birth. . The higher risk of embryonic tumors was driven primarily by a higher rate of younger tumors. Children conceived by IVF were more than twice as likely to have younger tumors than other children in the study.
Children born with IVF were also 41 per cent more likely to develop embryonic tumors in the central nervous system, which occurs when embryonic cells remain in the brain after birth.
Cell tumors called viruses, or malignancies in the reproductive tissue such as the testicles or ovaries, were more than twice as common as IVF.
Generally, children conceived by IVF were 17 per cent more likely to develop cancer.
The study was not a controlled experiment designed to test whether IVF could directly cause cancer. Researchers also did not compare the results of infertile couples who used IVF to other infertile couples, making it difficult to see how the causes of infertility could influence the potential for rare childhood cancers.
It is possible that cancer may be caused by chromosomal abnormalities, says Dr Norbert Gleicher, medical director of the Center for Human Reproduction in New York City.
"As eggs grow older, chromosomal instability is increasing," says Gleicher, who was not part of the study, by email. "This has been known for decades and is the cause of more pregnancy and unusual chromosomal miscarriages with age developing, but this chromosomal instability also leads to more mutations in Wales. different genes, many of which can cause cancer.
Couples considering IVF should not let the small risk of childhood cancer influence their decisions, advised Gleicher.
"Having a doctor visit is dangerous because a car can be over run by a car on the road, but again, we go to doctors through the time because the risk is very low and the potential gain is t much higher than the risk, "said Gleicher. "The same principle applies here: there are risks in IVF but they are very low (as far as we can see so far) and so are worth taking."
SOURCE: http://bit.ly/2HRyovk JAMA Pediatrics, online April 1, 2019.