Childhood cancer in relation to prenatal exposure to chickenpox

Childhood cancer research in Oxford I: the Oxford Survey of Childhood Cancers

BACKGROUND

Significant research on the epidemiology and natural history of childhood cancer took place in the Universities of Oxford and Birmingham over sixty years. This is the first of three papers recording this work and describes the Oxford Survey of Childhood Cancers (OSCC), the largest case-control survey of childhood cancer ever undertaken.

METHODS

The OSCC studied deaths in Britain from 1953 to 1981. Parents were interviewed and medical records from ante-natal clinics and treatment centres were followed up and abstracted. The survey left Oxford in 1975 and was run subsequently from Birmingham. The data are now being documented and archived to make them available for future study.

RESULTS

Many papers have resulted from this survey, most notably those relating to the association first reported therein between childhood cancer and ante-natal X-raying. This paper is a historical review of the OSCC.

CONCLUSIONS

In spite of many analyses of the study, this historic data set has continuing value because of the large number of examples of some very rare tumours and the detailed clinical and family history data that are available; and also because of the possibility of carrying out new analyses to investigate emerging research issues.

Epidemiological evidence of childhood leukaemia around nuclear power plants

A few reports of increased numbers of leukaemia cases (clusters) in children living in the vicinity of nuclear power plants (NPP) and other nuclear installations have triggered a heated debate over the possible causes of the disease. In this review the most important cases of childhood leukaemia clusters around NPPs are described and analyzed with special emphasis on the relationship between the environmental exposure to ionizing radiation and the risk of leukaemia. Since, as indicated, a lifetime residency in the proximity of an NPP does not pose any specific health risk to people and the emitted ionizing radiation is too small to cause cancer, a number of hypotheses have been proposed to explain the childhood leukaemia clusters. The most likely explanation for the clusters is 'population mixing', i.e., the influx of outside workers to rural regions where nuclear installations are being set up and where local people are not immune to pathogens brought along with the incomers.

Maternal use of antibiotics and cancer in the offspring: results of a case-control study in Germany

OBJECTIVE

As previous results were inconsistent, we assessed the association between maternal use of antibiotics during pregnancy or 3 months before conception and childhood cancer in the offspring in a large case-control study in Germany.

METHODS

This population-based study on potential risk factors for childhood cancer was conducted by the German Childhood Cancer Registry (GCCR) and included a total of 1,867 registered cancer cases aged 0-14, diagnosed between October 1992 and September 1994. A total of 2,057 controls were randomly drawn from population registries, matched by age, gender, and region. Conditional logistic regression models for frequency-matched datasets were used to estimate odds ratios (OR) with 95% confidence intervals (95% CI).

RESULTS

Positive statistically significant associations with self-reported maternal antibiotic use were observed for acute lymphoid leukemia (based on 59 mothers exposed to antibiotics, OR = 1.47; 95% CI: 1.06-2.04), acute myeloid leukemia (18 exposed, OR = 3.21; 95% CI: 1.83-5.62), and Burkitt lymphoma (three exposed, OR = 5.89; 95% CI: 1.47-23.69), but not other cancer types.

CONCLUSIONS

The results provide some support for the hypothesis that maternal use of antibiotics increases the risk of cancer in the offspring. Although recall bias is a concern, it is unlikely that this fully explains the observed effect. Further, the observed associations might be related to the underlying infections.

Early child-care and preschool experiences and the risk of childhood acute lymphoblastic leukemia

An infectious etiology for childhood acute lymphoblastic leukemia (ALL) has been suggested, yet few studies have focused on the role of early child care. Day-care histories were examined in a case-control study of ALL in New York State. Cases (n = 255) were diagnosed at one of four referral centers between 1980 and 1991; controls (n = 760) were randomly selected from livebirths in the 31 counties served by the referral centers. Self-administered questionnaires were mailed to the parents of cases and controls in 1995. Day-care histories were censored at the age of diagnosis for cases and at an equivalent date for controls. The odds ratio for children who stayed at home compared with those who attended day care for >36 months was 1.32 (95% confidence interval (CI): 0.70, 2.52); the odds ratios for 1-18 and 19-36 months of day care were 1.74 (95% CI: 0.89, 3.42) and 1.32 (95% CI: 0.64, 2.71), respectively. Elimination of cases with T-cell ALL enhanced the risk. Starting care at an earlier age was not associated with a decreased risk of ALL. These findings do not support the hypothesis that infrequent contact with peers during early childhood could delay exposure to infectious diseases and increase the risk of ALL.

Long term effects of exposure to viral infections in utero

An analysis was conducted of the major findings of a long term follow up study of 3076 subjects who were exposed to viral infections in utero and who at the time of analysis were up to 40 years of age. Mortality and morbidity were compared with those in a control population matched for sex and date and area of birth. An excess of cancers (16 cases against seven) appeared to be clustered among those exposed to herpes viruses (varicella or cytomegalovirus). There was evidence of an increased risk of diabetes among those exposed to mumps during the first trimester (four cases among 128 subjects against none in 148 controls). The most surprising finding was a decrease of diseases of the skin and subcutaneous tissue and of the nervous system among subjects exposed to antenatal varicella zoster infection. The mechanism for the association may include production of fetal anti-idiotype antibodies in response to transplacentally acquired maternal autoantibodies.

The effects of ionizing radiation, microwaves, and ultrasound on the developing embryo: clinical interpretations and applications of the data

The term "radiation" evokes emotional responses both from lay individuals and from professionals. Many spokespersons are unfamiliar with radiation biology or the quantitative nature of the risks. Frequently, microwave, ultrasound, and ionizing radiation risks are confused. Although it is impossible to prove no risk for any environmental hazard, it appears that exposure to microwave radiation below the maximal permissible levels present no measurable risk to the embryo. Ultrasound exposure from diagnostic ultrasonographic imaging equipment also is quite innocuous. It is true that continued surveillance and research into potential risks of these low-level exposures should continue, but at present ultrasound not only improves obstetric care but also reduces the necessity of diagnostic x-ray procedure. In the field of ionizing radiation, we have as good a comprehension of the biologic effects and the quantitative maximum risks as of any other environmental hazard. Although the animal and human data support the conclusion that no increases in the incidence of gross congenital malformations, intrauterine growth retardation, or abortion will occur with exposures below 5 rad, that does not mean that there are definitely no risks to the embryo exposed to lower doses of radiation. Whether there exists a linear or exponential dose-response relationship or a threshold exposure for genetic, carcinogenic, cell-depleting, and life-shortening effects has not been determined. In establishing maximum permissible levels for the embryo at low exposures, we use the information in Tables 2, 3, 4, 7, 10, and 14. It is obvious that the risks of 1-rad or 5-rad acute exposure are far below the spontaneous risks of the developing embryo, since 15% of human embryos abort, 2.7%-3.0% of human embryos have major malformations, 4% have intrauterine growth retardation, and 8%-10% have early- or late-onset genetic disease. The maximum risk attributed to a 1-rad exposure, approximately 0.003%, is thousands of times smaller than the spontaneous risks of malformations, abortion, or genetic disease (see Table 10). Thus, the present maximum permissible occupational exposures of 0.5 rem for pregnant women and 5 rem for medical exposure are extremely conservative. Medically indicated diagnostic roentgenograms are appropriate for pregnant women, and there is no medical justification for terminating a pregnancy in women exposed to 5 rad or less because of a radiation exposure.(ABSTRACT TRUNCATED AT 400 WORDS)