These researchers investigated the role that demographic and tumour factors play in explaining ethnic inequalities in breast cancer survival, among 2,968 breast cancer cases notified to the New Zealand Cancer Registry (NZCR) from April 2005 to April 2007 that were followed-up to April 2009. Māori, Pacific and non-Māori/non-Pacific women were categorised according to ethnicity on the NZCR and comprised 17%, 76.5% and 6.5% of the study cohort, respectively. There were 433 recorded deaths. Relative survival rates at 4 years were 91.5% for non-Māori/non-Pacific, 86.2% for Māori, and 79.6% for Pacific women. Using non-Māori/non-Pacific as the reference group, the age-adjusted hazard ratio decreased for Māori from 1.76 to 1.43 when further adjusted by deprivation (analysed as quintiles of the New Zealand area-based index of socio-economic position) and decreased for Pacific women from 2.49 to 1.94. Inequalities persisted after adjustment for subtype variables (ER/PR/HER2), but adjusting for access to care variables (extent/size) eliminated the ethnic inequalities in excess mortality.
