Characteristics of and differences between Pasifika women and New Zealand European women diagnosed with breast cancer in New Zealand.

Aim: Breast cancer in New Zealand-based Pasifika women is a significant issue. Although Pasifika women have a lower incidence of breast cancer compared to New Zealand European women, they have higher breast cancer mortality and lower five-year survival. The aim of this study was to describe the characteristics and tumour biology of Pasifika women and to compare New Zealand European women to identify what factors impact on early (Stage 1 and 2) vs advanced stage (Stage 3 and 4) at diagnosis.

Method: Data on all Pasifika and New Zealand European women diagnosed with breast cancer (C50) during the period 1 June 2000 to 31 May 2013 was extracted from the Auckland and Waikato Breast Cancer Registries. Descriptive tables and Chi-square test were used to examine differences in characteristics and tumour biology between Pasifika and New Zealand European women. Logistic regression was used to identify factors that contributed to an increased risk of advanced stage at diagnosis.

Results: A significantly higher proportion of Pasifika women had advanced disease at diagnosis compared to New Zealand European women (33.3% and 18.3%, respectively). Cancer biology in Pasifika women was more likely to be: 1) HER2+, 2) ER/PR negative and 3) have a tumour size of ≥50mm. Pasifika women live in higher deprivation areas of 9-10 compared to New Zealand European women (55% vs 14%, respectively) and were less likely to have their cancer identified through screening. Logistic regression showed that if Pasifika women were on the screen-detected pathway they had similar odds (not sig.) of having advanced disease at diagnosis to New Zealand European women.

Conclusion: Mode of detection, deprivation, age and some biological factors contributed to the difference in odds ratio between Pasifika and New Zealand European women. For those of screening age, adherence to the screening programme and improvements in access to earlier diagnosis for Pasifika women under the current screening age have the potential to make a substantial difference in the number of Pasifika women presenting with late-stage disease.