Childhood cancer in New Zealand 1990 to 1993

The effect of race on the incidence of retinoblastoma

PURPOSE

To examine the incidence of retinoblastoma for regional variations by race.

METHODS

Age-adjusted incidence rates, rate ratios, and 95% confidence intervals were determined in 109 regions from 1993 to 1997 using compiled data from the International Agency for Research on Cancer.

RESULTS

The rate ratio was 1.12 (range: 0.35 to 4.15) between white populations in the United States and Europe/Australia, 0.98 (range: 0.37 to 2.65) between Hispanic populations in Spain and the United States, and 1.44 (range: 0.29 to 1.79) between Hispanic populations in Uruguay and the United States. The rate ratio between Hispanic and white populations within the United States was 0.94 (range: 0.33 to 2.56). No differences were significant.

CONCLUSIONS

Because retinoblastoma is a genetic disease, its incidence is similar among varied populations.

Incidence of first primary central nervous system tumors in California, 2001-2005: children, adolescents and teens

This study used data from the California Cancer Registry to comprehensively examine first primary central nervous system tumors (PCNST) by the International Classification of Childhood Cancers (ICCC) diagnostic groups and to compare their incidence by age groups, sex, race/ethnicity, socioeconomic status and tumor behavior. The study period, 2001–2005, represents the first 5 years of benign PCNST data collection in the state. The age-adjusted incidence rates were 2.1 for malignant and 1.3 for benign per 100,000. Children younger than 5 years old had the highest incidence of malignant PCNST (2.6 per 100,000). Teens aged 15–19 had the highest incidence of benign PCNST (1.8 per 100,000). Age-specific incidence rates were nearly the same for Hispanics, non-Hispanic whites, and Asian/Pacific Islanders for malignant PCNST among children younger than 5 (2.6–2.7 per 100,000); non-Hispanic whites had the highest rates in the 5–14 year-old age group (2.5 per 100,000) and Asian/Pacific Islanders the highest among the 15–19 year old age group (2.3 per 100,000). We found no statistically significant differences in the incidence of malignant PCNST by race/ethnicity in any age group. Astrocytoma had the highest incidence for both malignant and benign histology in most age groups.

Epidemiology of childhood leukemia in New Zealand: studies of infectious hypotheses

The etiology of childhood leukemia remains an enigma despite decades of research. Hypotheses of an infectious etiology have been around for a long time, and in the last 20 years there have been two main theoretical contenders. One of these involves the possibility of a specific infectious agent having a causative role, and animal leukemia viruses would be analogous to this. Another theory relates to the possible involvement of unusual patterns of infections in infancy and how they might relate to aberrant immune responses. The first of these is easier to test. In New Zealand, since the early 1990s we have embarked on a program of research on the epidemiology of childhood leukemia. One of the goals has been to test hypotheses about the role of infection in causation. A variety of study designs have been employed, including descriptive, clustering, case-control and contributions to pooled international analyses. Some of the more interesting findings include: there has been a marked increase in the incidence of acute lymphoblastic leukemia among young children in New Zealand since the mid 1960s, poorer families are at greater risk, and there is no clear support for hypotheses of an infectious cause from the New Zealand data. However because of our small total population (4 million people) we cannot produce clear results on our own. Hence our current international collaborations, for example in CLIC (the Childhood Leukemia International Consortium) represent an important step forward. As countries work together across international boundaries we have a renewed hope that the causes of the childhood leukemias will be unlocked in the foreseeable future.

Survival by ethnicity for children diagnosed with cancer in New Zealand during 1990-1993

AIM

This study aimed to assess survival by ethnicity for all New Zealand children (0-14 years) diagnosed with cancer during 1990-1993 and second, to determine the accuracy of the children's routinely collected ethnicity information.

METHODS

Four hundred and nine children were followed up using two largely independent sources. We compared survival using the Cox model.

RESULTS

Maori and Pacific Island children had the same survival as non-Maori/non-Pacific children for 'all cancers combined' (hazard ratios (HR): 0.98; 95% confidence interval (CI): 0.64-1.50 and 1.01; 95% CI: 0.53-1.89 respectively) and acute lymphoblastic leukaemia (HR: 1.09; 95% CI: 0.45-2.62 and 0.99; 95% CI: 0.24-4.16, respectively). The ethnicity data stored within the National Health Index and the New Zealand Cancer Registry showed reasonably close agreement with ethnicity data provided by the children's mothers at interview (Kappa statistics: 0.82 and 0.81 respectively) while the Mortality Collection showed only moderate agreement (Kappa statistic: 0.63).

CONCLUSION

The point estimates in this study provide no evidence of ethnic disparities in survival from childhood cancer in New Zealand. However, even in this national study there were small numbers of Maori and Pacific children leading to wide confidence intervals. We therefore recommend cautious interpretation.

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.

International Classification of Childhood Cancer, third edition

BACKGROUND

The third edition of the International Classification of Diseases for Oncology (ICD-O-3), which was published in 2000, introduced major changes in coding and classification of neoplasms, notably for leukemias and lymphomas, which are important groups of cancer types that occur in childhood. This necessitated a third revision of the 1996 International Classification of Childhood Cancer (ICCC-3).

METHODS

The tumor categories for the ICCC-3 were designed to respect several principles: agreement with current international standards, integration of the entities defined by newly developed diagnostic techniques, continuity with previous childhood classifications, and exhaustiveness.

RESULTS

The ICCC-3 classifies tumors coded according to the ICD-O-3 into 12 main groups, which are split further into 47 subgroups. These 2 levels of the ICCC-3 allow standardized comparisons of the broad categories of childhood neoplasms in continuity with the previous classifications. The 16 most heterogeneous subgroups are broken down further into 2-11 divisions to allow study of important entities or homogeneous collections of tumors characterized at the cytogenetic or molecular level. Some divisions may be combined across the higher-level categories, such as the B-cell neoplasms within leukemias and lymphomas.

CONCLUSIONS

The ICCC-3 respects currently existing international standards and was designed for use in international, population-based, epidemiological studies and cancer registries. The use of an international classification system is especially important in the field of pediatric oncology, in which the low frequency of cases requires rigorous procedures to ensure data comparability.

Acute B cell lymphoblastic leukaemia in a 12-week-old greyhound

A 12-week-old greyhound had a two-day history of lethargy, inappetence and shifting lameness. Clinical examination revealed pyrexia and hepatosplenomegaly. Haematological examination showed anaemia, thrombocytopenla, neutropenla and large numbers of atypical mononuclear leucocytes. A diagnosis of acute B cell lymphoblastic leukaemia was made following flow cytometric immunophenotyping of the leucocytes. The owner declined further evaluation and the dog was treated symptomatically with antibiotics. After a brief improvement, the dog's condition deteriorated and it was euthanased four days after initial presentation. The case was unusual because acute lymphoid leukaemia in the dog is most frequently reported in mature animals. This is in contrast to humans, where acute leukaemia is one of the most common childhood cancers.

Epidemiology and genetics of childhood cancer

Childhood cancer is rare everywhere in the world, with age-standardized annual incidence usually between 70 and 160 per million at age 0-14 years. Greater variation is seen between populations for some specific tumour types. Some of the largest variations are geographical and are attributable to environmental factors, whereas variation mainly on ethnic lines seems likely to be a marker of genetic predisposition. A wide range of familial and genetic syndromes is associated with an increased risk of childhood cancer. Virtually all the excess risk of cancer among first-degree relatives of children with cancer can be accounted for by known hereditary syndromes. Studies of weak predisposition and gene-environment interaction have so far shown limited consistency. There are very few established environmental or exogenous risk factors and most of these are infective agents. Many putative risk factors can hardly ever be investigated epidemiologically except by interview or questionnaire studies. Some recent examples illustrate the continuing problems of participation bias and recall bias.

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.