"Young men undergoing treatment for cancer often want to know how the disease and its treatment affect their chances of fathering healthy children. Our large-scale study shows that there is a slightly higher risk of deformities, but the actual risk of having a child with deformities is nevertheless extremely low. I think this is good news!"
These words are from the cancer physician Olof Stahl, who has studied this issue in his coming dissertation from Lund University in Sweden.
It is known that undergoing radiation treatment and chemotherapy can affect male fertility. For this reason, attempts are always made nowadays to preserve and freeze sperm before cancer treatment starts. Just how fertility is affected then depends on the type of cancer and the type of treatment. The result can be anything from unaffected sperm production to complete loss of sperm production, with a middle group where production is impacted in a way that leaves fewer sperms with impaired mobility.
The question of possible connections between cancer and the risk of deformities in future children has been less thoroughly addressed. Can cancer have affected the sperms even though sperm production as such is entirely normal? And in cases requiring in vitro fertilization, IVF, is there a risk of using sperms that need help carrying out fertilization but also are bearing damaged genes? These issues have never been studied before.
Olof Stahl and his associates have now addressed the questions in a register study of 1.8 million children in Denmark and Sweden, born between 1994 and 2005. All children with deformities (chromosome disturbances, cleft palate, heart malformations, etc.) were pulled from the register and compared with data about possible cancers in their fathers and whether they were fertilized normally or via IVF. The study shows that there is a slightly elevated risk for deformity both among children born to former cancer patients and among children conceived via test-tube fertilization. The latter risk is already known, and it is regarded to be not so much due to IVF methods as to the fact that sperms that require IVF are of poorer quality. The risk elevation is small, however: from 3.2 percent - the 'natural' risk of deformity in children - to 3.7 percent and 3.8 percent respectively.
"This is such a tiny difference that it is virtually negligible. We also found that the combination of father-with-previous-cancer and IVF did not entail any further increase in risk. This is a great relief for former cancer patients who might be worried about the health of their future children," claims Olof Stahl.
The study is so new that it has not yet been published. The three other studies included in the dissertation were published in the journals Cancer, Human Reproduction, and International Journal of Andrology.