Extremely low-frequency magnetic fields and survival from childhood acute lymphoblastic leukemia: an international follow-up study.

A previous US study reported poorer survival in children with acute lymphoblastic leukemia (ALL) exposed to extremely low-frequency magnetic fields (ELF-MF) above 0.3 µT, but based on small numbers. Data from 3073 cases of childhood ALL were pooled from prospective studies conducted in Canada, Denmark, Germany, Japan, UK and US to determine death or relapse up to 10 years from diagnosis. Adjusting for known prognostic factors, we calculated hazard ratios (HRs) and 95% confidence intervals (CI) for overall survival and event-free survival for ELF-MF exposure categories and by 0.1 µT increases. The HRs by 0.1 µT increases were 1.00 (CI, 0.93-1.07) for event-free survival analysis and 1.04 (CI, 0.97-1.11) for overall survival. ALL cases exposed to >0.3 µT did not have a poorer event-free survival (HR=0.76; CI, 0.44-1.33) or overall survival (HR=0.96; CI, 0.49-1.89). HRs varied little by subtype of ALL. In conclusion, ELF-MF exposure has no impact on the survival probability or risk of relapse in children with ALL.

Population-based survival of children in New Zealand diagnosed with cancer during 1990-1993.

In this study, we have aimed to characterise the survival of all 0-14 year-old New Zealand children who were diagnosed with cancer during 1990-1993. Four hundred and nine children were followed up using two largely independent sources. We calculated Kaplan-Meier survival probabilities and investigated various prognostic factors using the Cox model. Five-year survival for all cancers was 66% (95% confidence interval (CI) 62-71%) and for acute lymphoblastic leukaemia it was 70% (CI 62-79%). Cancers with particularly favourable prognoses (followed by their respective 5-year survival probabilities) included: retinoblastoma 100% (CI 74-100%), Hodgkin's disease 93% (CI 79-100%), non-Hodgkin's lymphoma 87% (CI 73-100%) and osteosarcoma 91% (CI 74-100%). Cancers with poor prognoses included: neuroblastoma 35% (CI 14-56%), rhabdomyosarcoma 42% (CI 14-70%) and central nervous system tumours 49% (CI 38-60%). Girls with any cancer had a significantly lower risk of death than boys. Generally, survival for childhood cancers in New Zealand increased greatly between 1961-1965 and 1990-1993. Nevertheless, outcomes for some cancers remained poor.

Economic effects of childhood cancer on families.

OBJECTIVE: To assess the financial impact of childhood cancer on families. METHODS: This was a cross-sectional survey of parents caring for children who were diagnosed with cancer during the period 1990-1993. Self-administered questionnaires were completed by the parents of 237 children from throughout New Zealand with different types of cancer. Dollar amounts were adjusted to the equivalent of December 2000. RESULTS: Eighty-six per cent of the 192 living children were well or in remission. A further 45 children had died. The average extra amount spent, because of the child's illness, by the family of a living child in the 30 days prior to participation in the study was NZ$220 (SD NZ$330). On average, this was 13% of the family income after tax. After reported entitlement to compensation from various sources was allowed for, families were left with a mean deficit of NZ$157 (SD NZ$278) for the 30 days. Twelve families had a shortfall of more than NZ$500, including three families that had a shortfall of more than NZ$1000. Expenditure was greater for those whose children spent more time in hospital (P = 0.003). There was no significant association between the total cost and the distance travelled to the treatment centre (P = 0.96). For 24 families, after-tax income in the month prior to participation in the study was at least NZ$500 lower than it had been in the month before the child's diagnosis. Thirty-seven per cent of families reported that they needed to borrow money because of the financial effects of the child's illness. Bereaved parents spent an average of NZ$3065 (SD NZ$2168) on funeral expenses. CONCLUSION: There is a large financial burden on families who have a child with cancer.

Case-control study of parental age, parity and socioeconomic level in relation to childhood cancers.

BACKGROUND: Parental ages, parity, and social class have been found in some studies to be associated with particular childhood cancers. Further investigation is warranted because of conflicting findings, biases, and the need to test specific hypotheses. METHODS: A case-control study was conducted (England and Wales, ages 0-14 years). Cases were ascertained from the National Registry of Childhood Tumours, and were born and diagnosed during 1968-1986. Birth record controls were matched 1:1 to cases on date of birth, sex and area. Information on variables of interest for both groups came from birth records. In all, 10 162 pairs could contribute to matched analyses. RESULTS: The odds ratio (OR) for retinoblastoma resulting from assumed new germ cell mutations among children of fathers aged > or =45 years was 3.0 (95% CI : 0.2-41.7). The risk of childhood acute lymphoblastic leukaemia (ALL) was significantly higher among children of older mothers and fathers, and significant trends with increasing mothers' (P < 0.001) and fathers' (P = 0.002) ages were found. There was a strong and significant protective effect of increasing parity on risk of childhood ALL. The adjusted OR for parity of > or =5 (versus 0) was 0.5 (95% CI : 0.3-0.8). Children in more deprived communities had a lower risk of ALL; but this was not significant after confounders were allowed for. There was no significant effect of social class based on parental occupation on ALL risk, but the numbers were small in those analyses. CONCLUSIONS: The associations between ALL and parental ages did not disappear when children with Down syndrome were excluded, suggesting an additional explanation beyond known links. The strong ALL association with parity may be because of an unknown environmental risk factor.

Impact of childhood cancer on the mental health of parents.

BACKGROUND: When a child is diagnosed with cancer, the family experiences great stress and disruption to daily life. As part of a national study in New Zealand, we evaluated the mental health of mothers and fathers of children with cancer, making comparisons to parents of children from the general population. PROCEDURE: This was a cross-sectional study. All children diagnosed with cancer at ages 0-14 years in New Zealand during a defined period were ascertained from the national cancer registry and other databases. The population-based comparison children were selected using national birth records. Parents from both groups completed self-administered questionnaires containing the General Health Questionnaire (GHQ-12) and other measures. The analyses included 218 mothers and 179 fathers of children with cancer, and 266 mothers and 224 fathers of children in the comparison group. Multivariate regression was used to adjust for demographic and socioeconomic characteristics, life events, and social support. RESULTS: Mothers and fathers of children with cancer had poorer GHQ-12 and mood rating scores than those of controls. The adjusted difference in the mean total GHQ-12 score (comparing mothers of children with cancer to mothers of controls) was 2.2 (95% confidence interval 1.3-3.2). The 12 items of the GHQ were each scored 0-3, and the total score was the sum, so 2 points is a small difference. For fathers the difference was 1.5 (95% confidence interval 0.6-2.4). Some subgroups of cancer group parents had poorer emotional health scores than others, including those with poor social support and no paid employment and also those who were bereaved. CONCLUSIONS: We found statistically significant but small differences between the mental health of parents of children with cancer and controls. The small differences suggest that as a group the parents of children with cancer are relatively resilient.

Infections, vaccinations, and the risk of childhood leukaemia.

A nationwide case-control study was conducted in New Zealand, to test hypotheses about the role of infections in the aetiology of childhood leukaemia. Children aged 0-14 years with leukaemia were matched on age and sex to controls selected from birth records. Case ascertainment was virtually complete and 121 (92%) of 131 eligible case families took part. The participation rate among the 303 first-choice eligible controls was 69%. Home interviews and serological tests were conducted. Adjusted relative risks were estimated by logistic regression. There was an increased risk of leukaemia in relation to reported influenza infection of the child during the first year of life (adjusted odds ratio 6.8, 95% confidence interval 1.8-25.7). This could be a chance finding due to multiple comparisons, and it should be tested elsewhere. Some key variables relevant to Greaves' hypothesis were not associated with B-cell precursor acute lymphoblastic leukaemia (numbers of infections and vaccinations, firstborn status, attendance at preschool groups), although a small effect could not be ruled out with a study of this size. Leukaemia risk was higher among children in poorer social circumstances, and this was true for all eligible children as well as for the participants.

Childhood cancer in New Zealand 1990 to 1993.

An epidemiological study of childhood cancer in New Zealand identified 409 children aged 0 to 14 years with malignant neoplasms newly diagnosed between 1990 and 1993 inclusive. The original microscopic material on which the diagnoses were based was reviewed in 398 cases and the neoplasms were allocated into the 12 major groupings and 48 further subcategories of the International Classification of Childhood Cancer (ICCC). The pathology reviewers agreed with group and subcategory classification of the confirmed cancers in all but one case of acute leukemia and three cancers of the central nervous system. Changes were also made in the FAB classification of three cases of acute non-lymphocytic leukemia and in the further subcategorisation of three Hodgkin's lymphomas and ten astrocytomas. The results show a high level of diagnostic accuracy for confirmed childhood neoplasms in that time period. Nine of 15 cases of malignant melanoma notified to the study were not confirmed for various reasons, which included a change in the pathological diagnosis in four cases. Compared with Victoria (Australia), New Zealand has a high incidence rate of lymphomas in boys and an unusual female preponderance of Wilms' tumor cases.

An assessment of spatial clustering of leukaemias and lymphomas among young people in New Zealand.

STUDY OBJECTIVE: To assess spatial clustering of childhood leukaemias and lymphomas in New Zealand, using a national dataset from a country with no nuclear installations. DESIGN: New Zealand Map Grid coordinates, derived from the birth addresses of cases and controls were used in clustering analyses that applied Cuzick and Edwards' method. SETTING: The whole of New Zealand. PARTICIPANTS: The cases were ascertained from the New Zealand Cancer Registry. They were diagnosed with leukaemia or lymphoma at ages 0-14 years during the period 1976 to 1987. For Hodgkin's disease, the age range was extended to include those aged from 0-24 years. The cancer registrations were linked with national birth records, to obtain the birth addresses of the cases. The controls were selected at random from birth records, with matching to cases (1:1) on age and sex. The analyses included 600 cases and 600 controls. MAIN RESULTS: There was no statistically significant spatial clustering for any tumour group overall, including acute lymphoblastic leukaemia, acute nonlymphoblastic leukaemia, other leukaemias, non-Hodgkin's lymphomas, Hodgkin's disease, and all these combined. Significant clustering was found in a sub-analysis for one of three age specific subgroups of acute lymphoblastic leukaemia (ages 10-14 years, p = 0.003). CONCLUSION: The subgroup finding may have been real or a chance association, as several comparisons were made. This study found little evidence for spatial clustering of leukaemias or lymphomas in a population with no nuclear installations.

Electromagnetic field exposures and childhood leukaemia in New Zealand.

A nationwide case-control study of childhood leukaemia in New Zealand included measurements of electric and magnetic fields in children's homes. There was no significant association between leukaemia and the time-weighted average of the 50 Hz magnetic or electric fields in the bedroom and living (or daytime) room combined.

Electromagnetic field exposures and childhood cancers in New Zealand.

OBJECTIVES: To assess childhood cancer risks for electromagnetic field (EMF) exposures. METHODS: A case-control study was conducted in New Zealand. Cases (aged from zero to 14 years) were ascertained from national databases including the New Zealand Cancer Registry; 303 took part (participation rate, 88 percent). The 303 age- and gender-matched controls were selected randomly from birth records (participation, 69 percent). Mothers were interviewed about appliance exposures (all cases and controls), and 24-hour residential measurements of EMFs were made (leukemia cases and matched controls). RESULTS: For the various appliance exposures, there were some odds ratios (OR) above 1.0 and others below 1.0. For electric blanket use by the child before diagnosis, the adjusted ORs were: leukemia, 2.2 (95 percent confidence interval [CI] = 0.7-6.4); central nervous system cancers, ORs = 1.6 (CI = 0.4-7.1); and other solid cancers, OR = 2.4 (CI = 1.0-6.1). Leukemia risk was increased for the highest category of the mean measured bedroom magnetic field (> or = 0.2microT cf < 0.1 microT), with an adjusted OR of 15.5 (CI = 1.1-224). A gradient in OR with exposure was not shown (middle category: OR 1.4, CI = 0.3-7.6), and there was no association with exposure categorized into thirds based on controls' exposure. The adjusted OR for leukemia in relation to the measured daytime room magnetic field (> or = 0.2 microT cf < 0.1 microT) was 5.2 (CI = 0.9-30.8). CONCLUSIONS: This was a small study and multiple comparisons were made. The positive findings thus should be interpreted cautiously.

The accuracy and completeness of childhood cancer registration in New Zealand.

The New Zealand Cancer Registry (NZCR) is the main source of data on cancer incidence in New Zealand. The accuracy and completeness of registration of childhood cancers (ages zero to 14 years) were assessed during the conduct of a case-control study. Newly diagnosed children (1990-93) were ascertained from three sources: the NZCR; the Patient Management System (hospital admissions and discharges); and the separate Children's Cancer Registry. Pathology reviews were conducted to verify the diagnoses. Capture-recapture methods were used to assess the completeness of ascertainment. During the four-year period, 409 incident cases of childhood cancer were confirmed, giving an age-standardized incidence rate of 131 per million person-years (95 percent confidence interval = 119-144). The NZCR ascertained 395 (97 percent) of these children. In addition, the NZCR notified us of 43 other 'childhood cancer' registrations which were not confirmed as new cases of childhood cancer according to our eligibility criteria. The main reasons for these were coding errors (20 registrations), duplicates (seven), and a change in the pathological diagnosis as a result of the pathology review (seven). The capture-recapture estimate of the total number of incident cases was 410. Overall, the NZCR had good completeness for childhood cancers, but the number of unconfirmed registrations was larger than expected.

Childhood leukaemias in New Zealand: time trends and ethnic differences.

Registrations from the New Zealand Cancer Registry were used to examine time trends in the incidence of leukaemias among children aged 0-14. There was a statistically significant increase in the incidence of leukaemia among children aged 0-4 during 1953-57 to 1988-90. In this age group, the recorded incidence rate increased from 4.89 per 100,000 person-years in 1953-57 to 7.92 in 1988-90. During 1973-77 to 1988-90 (and probably in earlier years), the increase was due to an increase in acute lymphoblastic leukaemia (ALL). The trends were unlikely to be due to changes in diagnosis or case ascertainment. The childhood leukaemia trends might be related to trends in family size, maternal age, socioeconomic level or exposure to infections. However, there are uncertainties about the importance of these factors or about their trends. The incidence of acute non-lymphoblastic leukaemia (ANLL) decreased between 1968-72 and 1988-90. The time trends highlight the likely importance of environmental factors in the aetiology of childhood leukaemias in New Zealand. The risk of ALL was lower in the Maori than in the non-Maori population (relative risk Maori/non-Maori 0.74). The risk of ANLL was higher among Maori (relative risk 1.84).

New Zealand hospital records insufficient for vitamin K study.

AIMS: To assess the availability and completeness of existing hospital records, required for a proposed case-control study of vitamin K administration to neonates and childhood cancer. METHODS: We surveyed 44 hospitals, to see whether they had kept records for children born during 1962-87. Additionally, we sought the neonatal records of 44 Dunedin-born people who would be in the proposed study if it went ahead. We abstracted details of vitamin K administration from the records found. RESULTS: There were 36 responses to our survey (82%). For two-thirds of the hospitals, neonatal records were not available for all of the period 1962-87. The commonest reason for unavailability of records was that they had been destroyed. Neonatal records could be found for 34 (77%) of those born in Dunedin. Although 30 records indicated that vitamin K had been given, only 17 gave the route of administration. CONCLUSIONS: Our proposed study is not feasible because of the poor availability of records and the lack of details recorded. We support the introduction of regulations requiring hospitals to retain health information for a specified time, and we argue that the minimum period for hospitals should be longer than has been proposed.

The difficulties and costs of ethical assessment of a national research project.

In 1990 we applied to the 14 area health board ethical committees for approval of a national study of childhood cancer. All the committees approved the study, but the process was time consuming and costly. The times taken for the committees to grant approval, ranged from two to 36 weeks. The committees had differing requirements. We recommend that a single ethical committee should take responsibility for dealing with each multicentre study in New Zealand. This would ensure uniformity of approach, and minimise delays and costs.

Outpatient clinic nonarrivals and cancellations.

OBJECTIVES: outpatient clinics account for much of the work and expenditure in public hospitals. Many hospitals are trying to improve clinic efficiency. This research was conducted to assess the extent and characteristics of outpatient nonarrivals and cancellations at Dunedin Hospital, and to make suggestions for improvements. METHODS: data on 37,271 appointments scheduled during six months of 1990 were obtained. Nonarrivals and cancellations were examined in relation to characteristics of the patient, clinic and appointment. RESULTS: a large proportion (21.2%) of the appointments were not completed, comprising 8.3% nonarrivals, 7.5% patient cancellations, and 5.4% clinic cancellations or reschedulings. Nonarrivals were related to characteristics of the patient; including age, sex, ethnic group, and marital status. The proportions of nonarrivals and cancellations varied among different clinics. For new appointments, longer waiting times from referral were related to nonarrivals and patient cancellations. CONCLUSIONS: outpatient nonarrivals and cancellations pose a large problem at Dunedin Hospital. They could be reduced if some clinics provided more information for patients, arranged better cover for consultant absences, minimised clerical errors, decreased waiting times for new referrals, and used patient reminders.

Stomach cancer in New Zealand: time trends, ethnic group differences and a cancer registry-based case-control study.

Stomach cancer trends in New Zealand were examined. Age-standardized mortality and incidence rates have declined over the past four decades, as in other countries. Rates have been consistently higher for men, and for Maori. A cancer registry-based case-control study of 1016 male stomach cancer cases and 19,042 male controls with other cancers was also conducted, to evaluate the relationships between stomach cancer and specific occupations. Adjustment was made for age, ethnicity, socioeconomic level, and smoking status. When 22 occupational groups were examined, adjusted odds ratios (ORs) and 95% confidence intervals (95% Cls) were elevated above unity for only one group: forestry workers (OR 1.83, 95% Cl 1.01-3.32). When two large, heterogeneous groups were broken down into 15 subgroups, adjusted ORs and 95% Cls elevated above unity were found for three sub-groups: grain millers and related workers; brewers, wine and beverage makers; and field crop workers. These findings may be because of the multiple comparisons and subgroup analyses undertaken. Men who had ever smoked cigarettes were found to have an increased stomach cancer risk compared to those who had never smoked (adjusted OR 1.36, 95% Cl 1.15-1.60).