Joint disease mapping using six cancers in the Yorkshire region of England

Amy Downing¹ , David Forman¹^,2 , Mark S Gilthorpe³ , Kimberley L Edwards¹ and Samuel OM Manda⁴

¹Cancer Epidemiology Group, Centre for Epidemiology & Biostatistics, University of Leeds, Room 8.49 Worsley Building, Leeds, LS2 9LN, UK

²Northern & Yorkshire Cancer Registry & Information Service, Bexley Wing, St James's University Hospital, Beckett Street, Leeds, LS9 7TF, UK

³Biostatistics Unit, Centre for Epidemiology & Biostatistics, University of Leeds, Room 8.49 Worsley Building, Leeds, LS2 9LN, UK

⁴Biostatistics Unit, South African Medical Research Council, 1 Soutpansberg Road, Pretoria, Private Bag x385, 0001, Pretoria, South Africa

author email corresponding author email

International Journal of Health Geographics 2008, 7:41doi:10.1186/1476-072X-7-41


Published:	28 July 2008

Abstract

Objectives

The aims of this study were to model jointly the incidence rates of six smoking related cancers in the Yorkshire region of England, to explore the patterns of spatial correlation amongst them, and to estimate the relative weight of smoking and other shared risk factors for the relevant disease sites, both before and after adjustment for socioeconomic background (SEB).

Methods

Data on the incidence of oesophagus, stomach, pancreas, lung, kidney, and bladder cancers between 1983 and 2003 were extracted from the Northern & Yorkshire Cancer Registry database for the 532 electoral wards in the Yorkshire region. Using postcode of residence, each case was assigned an area-based measure of SEB using the Townsend index. Standardised incidence ratios (SIRs) were calculated for each cancer site and their correlations investigated. The joint analysis of the spatial variation in incidence used a Bayesian shared-component model. Three components were included to represent differences in smoking (for all six sites), bodyweight/obesity (for oesophagus, pancreas and kidney cancers) and diet/alcohol consumption (for oesophagus and stomach cancers).

Results

The incidence of cancers of the oesophagus, pancreas, kidney, and bladder was relatively evenly distributed across the region. The incidence of stomach and lung cancers was more clustered around the urban areas in the south of the region, and these two cancers were significantly associated with higher levels of area deprivation. The incidence of lung cancer was most impacted by adjustment for SEB, with the rural/urban split becoming less apparent. The component representing smoking had a larger effect on cancer incidence in the eastern part of the region. The effects of the other two components were small and disappeared after adjustment for SEB.

Conclusion

This study demonstrates the feasibility of joint disease modelling using data from six cancer sites. Incidence estimates are more precise than those obtained without smoothing. This methodology may be an important tool to help authorities evaluate healthcare system performance and the impact of policies.