Biomedical subjects
Pat Ansell
Publications and source records attributed to Pat Ansell.
Childhood leukaemia and socioeconomic status: fact or artefact? A report from the United Kingdom childhood cancer study (UKCCS).
BACKGROUND: It is widely believed that children of high socioeconomic status (SES) are more likely than those of low SES to develop acute lymphoblastic leukaemia (ALL). Such observations have led to wide-ranging speculations about the potential aetiological role of factors associated with affluence and modernization. METHODS: Children (0-14 years) newly diagnosed with cancer in the UK between 1991 and 1996 were ascertained via a rapid hospital-based case finding system (n = 4430, of which 1578 were ALL). Children without cancer (controls) were randomly selected from primary care population registries for comparative purposes (n = 7763). Area-based deprivation scores were assigned as markers of SES at two time points - birth and diagnosis. An individual-based marker of SES - social class - was assigned using father's occupation as recorded on the child's birth certificate. RESULTS: No differences in area-based measures of deprivation were observed between cases and controls at time of diagnosis, either for all cancers combined [n = 4430, odds ratio (OR) = 1.00 (95% confidence intervals (CI) 0.98-1.01)] or for ALL alone (n = 1578 OR = 0.99, 95%CI 0.96-1.01). Findings were similar at time of birth (all cancers, OR = 0.99 95%CI 0.98-1.01, ALL OR = 0.98, 95%CI 0.96-1.00). In addition, no case-control differences were observed when an individual-based measure of SES - social class - based on father's occupation at time of birth was used. CONCLUSIONS: The comprehensive nature of the data, coupled with complete case-ascertainment and representative population-based controls suggests that SES in the UK is not a determinant of ALL in children. We believe the small effects reported for SES in some past studies may be artefactual.
Molar pregnancy, childhood cancer and genomic imprinting - is there a link?
The United Kingdom Childhood Cancer Study (UKCCS) is a national multi-centre case-control study that was designed to evaluate the potential aetiological role of prenatal events in childhood cancer. The obstetric records of 2692 mothers of children diagnosed with cancer and 4864 mothers of children without cancer were available for analysis. Overall, 1754 (65%) case mothers and 3220 (66%) control mothers had at least one prior pregnancy before the birth of the index child. Of these, 12 (0.68%) of the former and 9 (0.28%) of the latter had a prior molar pregnancy (odds ratio 2.5, 95% confidence interval 1.1 - 6.1). Both childhood cancer and molar pregnancy are rare neoplastic events, and the numbers are small. Nonetheless, whilst the associations were strongest for common precursor B-cell acute lymphoblastic leukaemia (OR 5.2, 95% CI 1.9 - 14.7) and sarcoma (OR 6.2, 95% CI 1.3 - 30.3), the spread across the remaining diagnostic groups suggests that the relationship, if confirmed, may be of a generalized, rather than specific, type. This is the first time that an association between childhood cancer and hydatidiform mole has been reported. The UKCCS's systematic use of clinical records permitted a more precise characterization of reproductive events than is possible in investigations that rely on individuals own accounts, and we are confident that our findings cannot be explained by recall bias or other methodological limitations. Accordingly, we suggest that there may be an aetiologic connection between molar pregnancy and childhood cancer, and speculate here on the various genetic/epigenetic mechanisms that could be involved.
Ovulation induction, assisted conception and childhood cancer.
Rapid advances have been made in the treatment of infertility over the last 30 years following the introduction of in vitro fertilisation and intracytoplasmic sperm injection. Whilst effects of assisted reproductive technology (ART) on birth outcomes are well documented little is known about effects on child health after the neonatal period. Childhood cancer is one area warranting further examination. The hypothesis that cancer in children may be initiated during early fetal development means that events leading up to and around conception may be important. Whilst the few large-scale epidemiological studies that have looked at childhood cancer incidence following ART have failed to find any significant increased risk, some case-control studies have reported an increased risk of specific cancers. However, it is important not to over interpret these findings as the reason for the infertility may be the predisposing factor, rather than the procedure itself. Recent recommendations by the UK's National Health Service to offer intra-uterine insemination and one free treatment cycle for infertile couples will result in increasing numbers of children born following ART. More detailed investigations that include larger numbers plus sufficient follow-up periods and information on the underlying causes of the infertility are needed since long term outcomes for these children, in particular the risk of developing cancer, remain largely unknown.