Case-control study of paternal occupation and social class with risk of childhood central nervous system tumours in Great Britain, 1962-2006

BACKGROUND

Paternal occupational exposures have been proposed as a risk factor for childhood central nervous system (CNS) tumours. This study investigates possible associations between paternal occupational exposure and childhood CNS tumours in Great Britain.

METHODS

The National Registry of Childhood Tumours provided all cases of childhood CNS tumours born and diagnosed in Great Britain from 1962 to 2006. Controls without cancer were matched on sex, period of birth and birth registration sub-district. Fathers' occupations were assigned to one or more of 33 exposure groups. A measure of social class was also derived from father's occupation at the time of the child's birth.

RESULTS

Of 11 119 cases of CNS tumours, 5 722 (51%) were astrocytomas or other gliomas, 2 286 (21%) were embryonal and 985 (9%) were ependymomas. There was an increased risk for CNS tumours overall with exposure to animals, odds ratio (OR) 1.40 (95% confidence intervals (CIs) 1.01, 1.94) and, after adjustment for occupational social class (OSC), with exposure to lead, OR 1.18 (1.01, 1.39). Exposure to metal-working oil mists was associated with reduced risk of CNS tumours, both before and after adjustment for OSC, OR 0.87 (0.75, 0.99).Risk of ependymomas was raised for exposure to solvents, OR 1.73 (1.02,2.92). For astrocytomas and other gliomas, risk was raised with high social contact, although this was only statistically significant before adjustment for OSC, OR 1.15 (1.01,1.31). Exposure to paints and metals appeared to reduce the risk of astrocytomas and embryonal tumours, respectively. However, as these results were the result of a number of statistical tests, it is possible they were generated by chance.Higher social class was a risk factor for all CNS tumours, OR 0.97 (0.95, 0.99). This was driven by increased risk for higher social classes within the major subtype astrocytoma, OR 0.95 (0.91, 0.98).

CONCLUSION

Our results provide little evidence that paternal occupation is a significant risk factor for childhood CNS tumours, either overall or for specific subtypes. However, these analyses suggest that OSC of the father may be associated with risk of some childhood CNS cancers.

Second and subsequent tumours among 1927 retinoblastoma patients diagnosed in Britain 1951-2004

Background:

Retinoblastoma is an eye tumour of childhood that occurs in heritable and non-heritable forms. In the heritable form, there is a predisposition to the development of non-ocular subsequent primary tumours (SPTs).

Methods:

This study included 1927 retinoblastoma patients diagnosed in Britain from 1951 to 2004. Ascertainment was through the (UK) National Registry of Childhood Tumours; cases were followed-up for the occurrence of SPTs. Standardised incidence ratios (SIRs) were calculated.

Results:

We identified 169 SPTs in 152 patients. The SIR analysis included 145 SPTs with cancer registrations from the years 1971 to 2009. These tumours occurred in 132 patients: 112 of the 781 heritable and 20 of the 1075 (presumed) non-heritable cases under surveillance at the start of this period developed at least one registered SPT. The SIRs for all tumours combined were 13.7 (95% confidence interval 11.3–16.5) in heritable cases and 1.5 (0.9–2.3) in non-heritable cases. The main types of SPT in the heritable cases were leiomyosarcoma, (31 cases; SIR 1018.7 (692.2–1446.0)), osteosarcoma (26 cases; SIR 444.6 (290.4–651.4)), and skin melanoma (12 cases; SIR 18.6 (9.6–32.4)).

Conclusion:

The risk of SPTs in heritable retinoblastoma is extremely high. This has important implications for the clinical follow-up and counselling of survivors and their families.

Paternal occupation and neuroblastoma: a case-control study based on cancer registry data for Great Britain 1962-1999

BACKGROUND

Neuroblastoma is the most common malignancy of infancy but little is known about the aetiological factors associated with the development of this tumour. A number of epidemiological studies have previously examined the risk associated with paternal occupational exposures but most have involved small numbers of cases. Here we present results from a large, population-based, case-control study of subjects diagnosed over a period of more than 30 years and recorded in the national registry of childhood tumours in Great Britain.

METHODS

A case-control study of paternal occupational data for 2920 cases of neuroblastoma, born and diagnosed in Great Britain between 1962 and 1999 and recorded in the National Registry of Childhood Tumours, and 2920 controls from the general population matched on sex, date of birth and birth registration district. Paternal occupations at birth, of the case or control child, were grouped by inferred exposure using an occupational exposure classification scheme. Conditional logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (95% CI), for each of the 32 paternal occupational exposure groups.

RESULTS

Only paternal occupational exposure to leather was statistically significantly associated with neuroblastoma, OR=5.00 (95% CI 1.07-46.93). However, this association became non-significant on correction for multiple testing.

CONCLUSION

Our findings do not support the hypothesis that paternal occupational exposure is an important aetiological factor for neuroblastoma.

Paternal occupation and retinoblastoma: a case-control study based on data for Great Britain 1962-1999

OBJECTIVES

To examine the association between paternal occupational exposures and retinoblastoma using birth registration data for cases from the National Registry of Childhood Tumours (NRCT) and controls from the general population of Great Britain.

METHODS

A case-control study of paternal occupational data for 1318 cases of retinoblastoma, born and diagnosed in Great Britain between 1962 and 1999, and 1318 controls matched on sex, date of birth and birth registration sub-district. Paternal occupations at birth were grouped according to inferred exposure using an occupational exposure classification scheme. A conditional (matched) case-control analysis was used to estimate odds ratios (OR) and 95% confidence intervals (95% CI) for each paternal occupational exposure group.

RESULTS

For non-heritable retinoblastoma, a statistically significant increased risk was found with father's definite occupational exposure to oil mists in metal working (OR = 1.85 (95% CI 1.05 to 3.36)). Together with a (non-significant) risk (OR = 1.64 (0.73 to 3.83)) amongst the heritable cases, this occupational exposure was also associated with a significant increased risk when all retinoblastoma cases were considered together (OR = 1.77 (1.12 to 2.85)). No statistically significant associations were observed for other exposure groups.

CONCLUSIONS

Our finding for exposure to oil mists in metal working (a subset of metal workers) is not directly comparable to those for metal working previously reported in the literature. Overall, our findings do not support the hypothesis that paternal occupational exposure is an important aetiological factor for retinoblastoma, however, the study has low power and other methodological limitations.

Non-ocular tumours following retinoblastoma in Great Britain 1951 to 2004

BACKGROUND

Retinoblastoma occurs in both a heritable and a non-heritable form. In the heritable form, there is a predisposition to the development of non-ocular tumours.

OBJECTIVES

To identify the types of non-ocular tumour occurring in retinoblastoma survivors and to produce estimates of risk for these tumours.

METHODS

We carried out a cohort study that included 1927 cases of retinoblastoma diagnosed in Great Britain between 1951 and 2004. Cases were ascertained through the National Registry of Childhood Tumours and followed up for the occurrence of non-ocular tumours using the routine notification system based on the National Health Service Central Registers in Britain.

RESULTS

Of the 1927 cases, 809 were known to have the heritable form of the disease and 1118 assumed to have the non-heritable form. 102 of the heritable and 13 of those classified as non-heritable developed a non-ocular tumour. The cumulative risk of developing such a tumour 50 years after retinoblastoma diagnosis was 48.3% (95% confidence interval: 38.1 to 59.7%) in the heritable and 4.9% (1.9 to 12.4%) in the non-heritable cases. The main categories of non-ocular tumours observed in the heritable cases were soft-tissue sarcomas (36 of which 21 were leiomyosarcoma), osteosarcoma (32), carcinoma (13), brain and central nervous system tumours (10), melanoma (9), leukaemia (4) and others (4). There were a total of 108 non-ocular tumours in 102 cases.

CONCLUSIONS

There is a high risk of non-ocular tumours occurring in survivors of heritable retinoblastoma. These results have important implications for the clinical follow-up and counselling of survivors.

Wilms tumour and paternal occupation: an analysis of data from the National Registry of Childhood Tumours

BACKGROUND

Wilms tumour is an embryonal malignant tumour that accounts for 90% of childhood kidney cancers. Parental occupational exposure has been hypothesised to be a cause of childhood Wilms tumour, in particular exposure to pesticides. However, the findings are inconsistent.

PROCEDURE

We have examined the association between paternal occupational exposures and Wilms tumour using birth registration data for cases (n = 2568) from the National Registry of Childhood Tumours (NRCT) and matched controls (n = 2,568) drawn from the general population of Great Britain. Paternal occupation, as recorded at the time of birth, was used to infer "occupational exposure" using a previously defined occupational exposure classification scheme. Odds ratios and 95% confidence intervals were generated using conditional logistic regression with exact methods to estimate the association between each paternal occupational exposure group and childhood Wilms tumour.

RESULTS

All odds ratios were close to 1.00 and no statistically significant associations were observed.

CONCLUSION

The results of this study failed to support any of the previously identified associations between paternal occupation and childhood Wilms tumour.

Retinoblastoma in Great Britain 1963-2002

AIM

This paper describes the epidemiology and family history status of 1601 children with retinoblastoma in Great Britain diagnosed 1963-2002 and summarises the practical consequences for diagnosis and counselling of developments in molecular genetics.

METHODS

Incidence rates were analysed according to year of diagnosis and tumour laterality. Cases were classified as heritable or non-heritable on the basis of laterality and family history of the disease.

RESULTS

There were 998 unilateral cases, 581 bilateral and 22 of unknown laterality. Bilateral cases tended to be diagnosed at a younger age than unilateral. All bilateral cases are regarded as heritable, and 35% had a family history of the disease. 7% of the unilateral cases had a family history and are therefore heritable. Thus, at least (41%) of our cases are heritable. This is an underestimate, since these data on family history are incomplete. For unilateral cases aged below 1 year, the reported incidence rate increased significantly (p<0.0001) by about 2.5% per year; for the age group 1-4 years, the average increase was about 0.5% per year (not significant).

Retinoblastoma incidence and survival in European children (1978-1997). Report from the Automated Childhood Cancer Information System project

Based on 2283 cases of retinoblastoma diagnosed in children aged 0-14 years, incidence and survival in Europe during the period 1978-1997 are described. Data were provided to the Automated Childhood Cancer Information System (ACCIS) from 60 paediatric and general cancer registries. During 1988-1997, the cumulative incidence of retinoblastoma in the ACCIS regions was found to be between 44.2 and 67.9 per million births. The highest incidence was seen in the first year of life. The age-standardised (World standard) incidence rate for the age-range 0-14 years was 4.1 per million. Approximately one-third of cases had bilateral tumours. Overall incidence increased over the period 1978-1997 by 1% per year, as derived from a model adjusted for sex, age group and type of registry (general or paediatric). The 5-year survival rate improved from 89% to 95% during the period covered by the study. This improvement was seen in both unilateral and bilateral cases but was significant only for the unilateral tumours. Survival was lower in the East region, although smaller differences were also observed between the other four regions (British Isles, North, South and West). Availability and quality of registration data on retinoblastoma need to be improved for effective evaluation of incidence and survival.

Allelic loss of IRF1 in myelodysplasia and acute myeloid leukemia: retention of IRF1 on the 5q- chromosome in some patients with the 5q- syndrome

Acquired interstitial deletions of the long arm of chromosome 5 occur frequently in the myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML). Recently IRF1, a putative tumor suppressor gene localized to the long arm of chromosome 5, has been shown to be deleted from the 5q- chromosome in a group of patients with MDS and AML. It has been suggested that the loss of IRF1 may be critical to the development of the 5q- syndrome. We have investigated the allelic loss of IRF1 in a group of 12 patients with MDS and a 5q deletion and 2 patients with AML and a 5q deletion. Gene dosage experiments demonstrated that 12 of 14 patients had loss of one allele of the IRF1 gene but no evidence of homozygous loss and that 2 patients with 5q- syndrome retained both copies of the gene. The retention of IRF1 on the 5q- chromosome in these two cases has been confirmed by fluorescent in situ hybridization localization using an IRF1 cosmid. Pulsed field gel electrophoresis was used to determine whether there was any evidence for structural rearrangement in the region encompassing the IRF1 gene in these two patients. No aberrant bands were detected with a range of rare cutter enzyme digests. We conclude that IRF1 maps outside the commonly deleted segment of the 5q- chromosome and that loss of IRF1 is not solely responsible for the development of the 5q- syndrome.

Identification of a CA repeat at the TCRA locus using yeast artificial chromosomes: a general method for generating highly polymorphic markers at chosen loci

The creation of a comprehensive genetic map in human has been limited by the lack of highly polymorphic markers spaced evenly throughout the human genome. We have utilized yeast artificial chromosomes (YAC) containing large human DNA inserts to help identify highly polymorphic (CA)n repeats at a chosen locus. The DNA of a YAC containing the locus was subcloned in M13 vectors, and the recombinants were screened at high stringency to detect preferentially long (CA)n repeats (n greater than 20). These repeats, which are the most likely to be highly polymorphic, were then studied to confirm both the level of polymorphism and their precise genetic location. This strategy has permitted the identification of a new, highly polymorphic CA repeat (77% heterozygosity) at the T cell receptor alpha chain (TCRA) locus on chromosome 14q. It provides a powerful marker for assessing the role of this locus in the susceptibility to autoimmune and infectious diseases. This approach should permit the development of highly polymorphic markers at any targeted locus and rapidly improve the current human genetic map.

Breast-milk IgA and lactoferrin survival in the gastrointestinal tract--a study in rural Gambian children

The survival of breast-milk secretory-IgA and lactoferrin has been investigated in 23 Gambian children aged 1.5, 3 and 17 months. Endogenous excretion of these immune proteins was measured in 7 weaned 34-month-old children. Defaecation rate was the prime determinant of faecal secretory-IgA and lactoferrin outputs, indicating that partial degradation occurs in the large intestine. Calculations showed that at least 30% of IgA and 2% of lactoferrin ingested from breast-milk must survive in the small intestine. Variations in faecal immune protein outputs were related to differences in intake and defaecation rate and were not affected by age or solid food consumption. The raised faecal outputs of 5 children with diarrhoea were a consequence of their high stool frequencies. IgA disappearance in the large intestine proceeded twice as fast in Gambian breast-fed children as in comparable Cambridge infants, suggesting that differences in gut flora may influence IgA survival. Thus breast-feeding, irrespective of age or additional food, can deliver significant quantities of these antimicrobial proteins to the small intestine but differences in defaecation rate and gut flora may affect their protective potential in the large intestine.

The nutritional role of breast-milk IgA and lactoferrin

The nutritional enigma concerning the extent to which breast-milk immune proteins are digested has been investigated by measuring the intakes and faecal outputs of IgA and lactoferrin over 7 days in 10 exclusively breast-fed (BF) and 9 formula-fed (FF) fullterm infants at 6 and 12 weeks post-partum. BF outputs (mg/day) greatly exceeded FF values (p less than 0.001): at 6 weeks secretory-IgA BF = 160 +/- 28, FF = 14 +/- 2, lactoferrin BF = 14 +/- 2, FF = 0.9 +/- 0.1; at 12 weeks secretory-IgA BF = 94 +/- 17, FF = 25 +/- 5, lactoferrin BF = 7 +/- 1, FF = 1 +/- 0.3. Secretory-IgA represented 42% and 27% of BF faecal protein at 6 and 12 weeks compared with 6% for FF infants at both ages. BF secretory-IgA outputs were highly correlated with intakes (r = 0.83, p less than 0.001). IgA and lactoferrin outputs and the presence of faecal secretory-IgA fragments in BF and FF infants were influenced by defaecation rate, suggesting that partial degradation occurred in the large intestine. By 6 weeks post-partum only 1% lactoferrin and 17% secretory-IgA intakes appeared in the faeces and 95% breast-milk protein could be regarded as nutritionally available. The elevated BF outputs of IgA and lactoferrin relative to endogenous excretion suggest, however, that breast-milk may still make a considerable contribution to intestinal defence mechanisms after the neonatal period despite the small proportion of daily intake which escapes digestion. The protective action of IgA and lactoferrin may also depend on their site of degradation and the nature of fragments.