Aims Worldwide, there have now been over 3 500 000 births after Assisted Reproductive Technology (ART). In the UK ART benefit many couples and currently 1.8% of births occur after ART. Rising usage accentuates the need for investigation of potential long term health threats to children conceived after ART. Cancer is one such adverse health outcome which has been investigated in several small studies. This systematic review aims to evaluate the evidence investigating possible increased risks of cancer in children conceived by ART. Where appropriate, data has been combined into a meta-analysis.
Methods Searches of MEDLINE and EMBASE were carried out using multiple combinations and variations of keywords ‘Neoplasm’, ‘Cancer’, ‘Assisted Reproductive Technology’, ‘in vitro fertilization’. An additional hand search of bibliographies of selected studies and review articles was carried out. All relevant identified studies were reviewed independently by two authors. Studies were classified according to design and cohort study quality assessed by two reviewers prior to inclusion in the meta-analysis. Standardised Incidence ratios were calculated for combined data from selected studies, comparing observed and expected cases of childhood cancer. STATA (version 10) was used for statistical analysis.
Results From over 4000 results, 59 relevant primary articles were identified, (21 cohort studies, 12 case-control studies and 26 case reports/series). Of the 21 cohort studies, 10 contained overlapping data and were thus excluded. The remaining 11 cohort studies were included in the meta-analysis. The combined standardised incidence ratio was 1.43 (95% CI 1.14 to 1.72). When restricted to higher quality, registry based studies SIR=1.32 (95% CI 1.09 to 1.55).
Conclusion The results suggest a small increased risk of childhood cancer after assisted conception. Additional larger population based studies are warranted to confirm this and to investigate risk of specific cancers. Should further studies have similar findings, underlying mechanisms also warrant investigation. Comprehensive, reliable data in this area are essential for pretreatment counselling of couples wishing to undergo ART, for facilitating early diagnosis and for broader public health reasons.
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