A large study has confirmed that modern chemotherapy regimes for childhood cancers can adversely affect both male and female fertility. However, it also indicates that the influence of chemotherapy is less pronounced on female fertility. The scientists behind the research say they hope their findings will encourage a greater focus on pre-treatment referral of young men to fertility centres.
The study, which was published in the Lancet Oncology, looked at the effect of 14 common chemotherapy drugs on more than 10,000 survivors of childhood cancer enrolled in the Childhood Cancer Survivor Study based at St Jude Children's Research Hospital in Memphis, in the USA.
The researchers recruited 4,000 of the patients' siblings as healthy controls, and found that 80 percent of these healthy men and women will have been pregnant or have got a partner pregnant by 45 years of age. For female survivors of childhood cancer, the figure is slightly reduced to 70 percent. But only 50 percent of boys who survive cancer will have fathered a child or got a partner pregnant by the age of 45.
But the 70 percent figure may hide a more worrying trend for female childhood cancer survivors, the study suggests. Pregnancy rates of survivors fell faster than the healthy siblings when subjects waited until after 30 to start a family. This may be because chemotherapy depletes the number of eggs in the ovaries, and accelerates menopause.
'We're not saying women have to have kids early but that people need to be aware that this and other studies suggest that even if overall, the impact on fertility is relatively minor, women do seem to be at higher risk of earlier menopause,' said lead author Dr Eric Chow of the Fred Hutchinson Cancer Research Centre.
The study also showed a strong association between use of the anti-cancer drug cisplatin and reduced fertility in male survivors. Dr Chow said that the link would 'need to be studied further', and added that 'all boys diagnosed [with cancer] post-puberty should be encouraged to bank their sperm to maximise their reproductive options in the future'.
Professor Richard Anderson from the University of Edinburgh, and Dr Hamish Wallace from the Royal Hospital for Sick Children, Edinburgh, both specialists who were not involved in the study, said that they hoped the results would heighten awareness of loss of fertility in male childhood cancer patients.
They added: 'For girls and young women, the data are generally more positive, but emphasise the need for accurate identification of the relatively small proportion who are at high risk, to avoid subjecting those at low risk to what might be invasive procedures.'
Radiotherapy has long been known to be damaging to young reproductive systems, and so chemotherapy is often used to treat childhood cancers instead. Childhood cancer now has an 80 percent survival rate into adulthood.