Intra-urban differences in breast cancer mortality: a study from the city of Malmo in Sweden

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Abstract
STUDY OBJECTIVE To assess whether in an urban population stage at breast cancer diagnosis is related to area of living and to what extent intra-urban differences in breast cancer mortality are related to incidence respectively stage at diagnosis. DESIGN National registries were used to identify cases. Mortality in 17 residential areas was studied in relation to incidence and stage distribution using linear regression analysis. Areas with high and low breast cancer mortality, incidence and proportion of stage II+ tumours at diagnosis were also compared in terms of their sociodemographic profile. SETTING City of Malmö in southern Sweden. PATIENTS The 1675 incident breast cancer cases and 448 deaths that occurred in women above 45 years of age in Malmö 1986–96. MAIN RESULTS Average annual age standardised breast cancer mortality ranged between residential areas, from 35/105 to 107/105, p=0.04. Mortality of breast cancer was not correlated to incidence, r= 0.22, p=0.39. The ratio of stage II+/0-I cancer incidence varied between areas from 0.45 to 1.99 and was significantly correlated to breast cancer mortality, r= 0.53, p=0.03. Areas with high proportion of stage II+ cancers and high mortality/incidence ratio were characterised by a high proportion of residentials receiving income support, being foreigners and current smokers. CONCLUSIONS Within this urban population there were marked differences in breast cancer mortality between residential areas. Stage at diagnosis, but not incidence, contributed to the pattern of mortality. Areas with high proportion of stage II+ tumours differed unfavourably in several sociodemographic aspects from the city average.