Breast cancer patients from more deprived areas have poorer survival

New research published by the National Cancer Registry and the Boyne Research Institute shows that breast cancer patients from more deprived areas in Ireland have a substantially higher risk of dying from their cancer than those from less deprived areas. The study (published in the journal PLOS ONE) followed up almost 30,000 women with breast cancer, with particular focus on 21,000 women diagnosed during the years 1999-2008. Some of the survival disparity reflected differences in stage at presentation and other factors examined. Similar findings have been noted in other countries, for a wide range of cancers, but this is the first detailed study of such disparities for breast cancer in Ireland.

Each patient was assigned to a deprivation category based on average socioeconomic characteristics of their area of residence (electoral division). Patients from the most deprived areas (about one-quarter of all patients) were about 30% more likely to die from their cancer than patients from the least deprived areas, having allowed for differences in patients’ age. This translated into, on average, 75% survival to five years after diagnosis in the most deprived group compared with 80% in the least deprived group. Comparison with 8,000 women diagnosed in earlier years (1994-1998) showed that survival disparities did not diminish over time, although survival of all groups did improve.

Patients from more deprived backgrounds were more likely to present with advanced stage, high grade or hormone receptor-negative cancer, factors associated with poorer prognosis. They were also more likely to present with symptoms (rather than through screening) and to be smokers; and less likely to have breast-conserving surgery (rather than mastectomy), though other treatment differences were minor. However, the analysis found that the available information on patient and tumour characteristics and on treatment could explain only about half of the survival disparity seen. This suggests that factors that were unmeasured, or difficult to quantify, may have accounted for the remaining disparity. 

Dr Julianne Byrne, one of the authors, commented “Persistent survival disparities among Irish breast cancer patients, although not fully understood, suggest unequal use of or access to health services. Our study highlights the need to understand and remove the behavioural or other barriers that may be involved.”

The period covered by this study pre-dates both full national coverage by the BreastCheck screening programme (which was launched as a national programme in 2007, and completed two rounds of national screening by 2013) and the National Cancer Control Programme’s Breast Symptomatic Services in the new cancer centres (which commenced in late 2009).