The New Zealand PIPER Project: colorectal cancer survival according to rurality, ethnicity and socioeconomic deprivation-results from a retrospective cohort study.

ABSTRACT

AIM: To investigate differences in survival after diagnosis with colorectal cancer (CRC) by rurality, ethnicity and deprivation. METHODS: In this retrospective cohort study, clinical records and National Collections data were merged for all patients diagnosed with CRC in New Zealand in 2007-2008. Prioritised ethnicity was classified using New Zealand Cancer Registry data; meshblock of residence at diagnosis was used to determine rurality and socioeconomic deprivation. RESULTS: Of the 4,950 patients included, 1,938 had died of CRC by May 2014. The five-year risks of death from CRC were Maori 47%; Pacific 59%; non-Maori-non-Pacific (nMnP) 38%. After adjustment for demographic characteristics, comorbidity and disease stage at diagnosis, compared to nMnP the relative risk (RR) for Maori was 1.1 (95%CI 0.8-1.3) and for Pacific 1.8 (95% CI 1.4-2.5). We found no differences in risk of death from CRC by rurality, but some differences by deprivation. CONCLUSIONS: Disparity in outcome following diagnosis with CRC exists in New Zealand. Much of this disparity can be explained by stage of disease at diagnosis for Maori, but for Pacific peoples and those in deprived areas other factors may influence outcome. Further analyses of the PIPER data will explore the impact of any differences in management.