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

Study objective-To assess whether in an urban population stage at breast ca ncer diagnosis is related to area of living and to what extent intra-urban differences in breast cancer mortality are related to incidence respectivel y stage at diagnosis. Design-National registries were used to identify cases. Mortality in 17 res idential areas was studied in relation to incidence and stage distribution using linear regression analysis. Areas with high and low breast cancer mor tality, incidence and proportion of stage II+ tumours at diagnosis were als o compared in terms of their sociodemographic profile. Setting-City of Malmo in southern Sweden. Patients-The 1675 incident breast cancer cases and 448 deaths that occurred in women above 45 years of age in Malmo 1986-96. Main results-Average annual age standardised breast cancer mortality ranged between residential areas, from 35/10(5) to 107/10(5), p=0.04. Mortality o f 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 an d was significantly correlated to breast cancer mortality, r=0.53, p=0.03. Areas with high proportion of stage II+ cancers and high mortality/incidenc e ratio were characterised by a high proportion of residentials receiving i ncome support, being foreigners and current smokers. Conclusions-Within this urban population there were marked differences in b reast cancer mortality between residential areas. Stage at diagnosis, but n ot incidence, contributed to the pattern of mortality. Areas with high prop ortion of stage II+ tumours differed unfavourably in several sociodemograph ic aspects from the city average.