Deutsch | Français | Italiano | English

 

Childhood leukaemia and lymphoma: are incidence and survival in Switzerland associated with socioeconomic status?

Summary

The research project aims to investigate the association of socio-economic status with the risk of developing childhood leukaemia or childhood lymphoma, and to explore whether the association is varying with the operational definition of socio-economic status.

Study Description 

Objectives: First, we aim to investigate the association of socio-economic status with the risk of developing childhood leukaemia or childhood lymphoma, and to explore whether the association is varying with the operational definition of socio-economic status. Second, we aim to investigate the association of socio-economic status with the five-year survival rate for cases of childhood leukaemia or childhood lymphoma.

Methods: The two main aims will be addressed by a case-control study design (for the association between SES and risk of disease) and by a prospective cohort study design of the included cases (for the differentials in mortality and survival). The study will include all cases of childhood leukaemia or lymphoma reported to the SCCR and diagnosed between 1991 and 2006 with a year of birth such that the diseased child has been recorded either in the 1990 or in the year 2000 census (approximately 700 leukaemia and 300 lymphoma cases). The restriction on being recorded in one of the censuses is needed to use the census information on profession and education of the child?s parents thus obtaining relevant information on SES. Furthermore we will be using information about the living conditions (number of rooms per person in the household, ownership of house or apartment) from the census data. Additionally, we will be using recently developed (sotomo, www.sotomo.geo.unizh.ch) area-based SES measures that are defined by the community in which a person lives. To obtain the SES information from the census records we will deploy methodologically sound probabilistic record linkage procedures that relate the cancer cases and the census records of all residents in Switzerland. For the case-control study we will select for each case 4 control children from the two census rounds. We thus anticipate 1000 case and 4000 control subjects in the case-control part of the study. Analysis will be performed by logistic regression and time-to-event analyses (life-table, Kaplan-Meier estimates and proportional hazards models).

Rationale and significance: Childhood leukaemia and childhood lymphoma comprise about half of all cancer diagnoses in children. Therefore, assessing SES as a risk factor for this subgroup is of public health importance. Using the population-based childhood cancer registry this study will hardly be hampered by biases involved in studying only selected subsets of cases.

Publications

Martin Adam, Cornelia E. Rebholz, Matthias Egger, Marcel Zwahlen, Claudia E. Kuehni.
Childhood leukemia and socioeconomic status: what is the evidence?
Radiation Protection Dosimetry, in press.

Study Team

- Adam, Martin (PM). Institute of Social and Preventive Medicine, University of Berne
- Zwahlen, Marcel (PL). Institute of Social and Preventive Medicine, University of Berne
- Kuehni, Claudia. Institute of Social and Preventive Medicine, University of Berne
- Spörri, Adrian. Institute of Social and Preventive Medicine, University of Berne
- Schmidlin, Kurt. Institute of Social and Preventive Medicine, University of Berne

Applicants

- Zwahlen, Marcel. Institute of Social and Preventive Medicine, University of Berne
- Egger, Matthias. Institute of Social and Preventive Medicine, University of Berne
- Kuehni, Claudia. Institute of Social and Preventive Medicine, University of Berne
- Von der Weid, Nicolas. Pediatric Oncology, CHUV Lausanne

Partner

- Swiss Paediatric Oncology Group (SPOG)
- Swiss National Cohort (SNC)

Funding

- Oncosuisse (Schweizerische Vereinigung gegen Krebs (USCC))
- Swiss Bridge

project duration

08.2007 - 07.2009

state

ongoing

Background: Some epidemiological studies suggested that acute lymphoblastic leukaemia (ALL) was more common among children of high socio-economic status (SES). However, more recent studies reported associations in the opposite direction. Infections have been implicated in the aetiology of lymphomas, which could, in turn, be reflected in SES differentials in lymphoma risk. The Swiss setting provides an ideal opportunity to study these questions, due to the existence of the population-based Swiss Childhood Cancer Registry (SCCR) and the availability of census records covering all inhabitants of Switzerland recorded in the years 1990 and 2000.