Comparison of prognostic and socio-economic factors in screen-detected and symptomatic cases of breast cancer

Background: The relationship between breast cancer and socioeconomic deprivation is complex. Although women from more deprived areas are less likely to get breast cancer, in general they experience poorer survival. A number of reasons have been proposed, including differences in tumour stage and tumour biology, but recent studies suggest that treatment factors or host response are the most important. The introduction of a national health service breast screening programme (NHSBSP) means that an additional factor now has to be taken into account. As deprived women are less likely to attend for screening we set out to determine the nature of the relationship between prognostic factors evident at diagnosis, screening status and socio-economic deprivation, in order to assess the implications for the NHSBSP. Methods: The NHSBSP computer systems and the Thames Cancer Registry (TCR) database were used to examine breast cancers diagnosed in women aged 50-64y during the period 1988-1992. Cases had previously been classified into screen-detected, interval cancers, eligible but not yet invited, non-attenders and those not registered with the programme. A prognostic score was assigned to each case using TCR data on the morphology and extent of the disease. Socio-economic comparisons were made from the women's postcodes and census details using the Carstairs method. Results: Screen-detected cases had a significantly better prognosis at diagnosis than those presenting with symptoms, and were less deprived than those who did not comply with the screening programme (by either failure to attend or not being registered). When the relationship between presentation status, deprivation and prognosis was assessed together, screen-detected cases had a better prognosis at diagnosis irrespective of deprivation level. Conclusion: The poor survival rate of deprived women with breast cancer due to host or treatment factors is likely to be compounded by poor attendance for screening. Unless the NHSBSP increases its efforts to target these women, the socio-economic gradient in breast cancer survival is likely to increase.