Ethnic, socio-demographic and socio-economic differences in surgical treatment of breast cancer in New Zealand

Background: Indigenous Maori are known to experience inferior quality cancer care compared with non-Indigenous Europeans in New Zealand. However, limited data are available on ethnic/socio-economic differences in surgical treatment of breast cancer, or reasons for such variations within the local context. We investigated ethnic/socio-economic differences in rates of mastectomy, sentinel node biopsy (SNB), post-mastectomy breast reconstruction and definitive local therapy for breast cancer in New Zealand. Methods: A retrospective review of prospective data in the Waikato Breast Cancer Register for women diagnosed during 1999-2012 was performed. Differences in rates of mastectomy (for stage I/II, T1/T2 cancers), SNB (for stage I/II, T1/T2, cN0 cancers), post-mastectomy breast reconstruction (for non-metastatic cancers in women < 70 years) and definitive local therapy (for stage I/II cancers) were analysed in univariate and multivariate regression models, adjusting for covariates. Results: Significantly lower mastectomy and higher reconstruction rates were associated with younger age, private compared with public hospital care and screen compared with non-screen detection. Compared with NZ Europeans, Maori (41% versus 33%, P = 0.025) were significantly more likely to undergo mastectomy for cancers, which were potentially amenable for breast conserving surgery, but were significantly less likely to undergo post-mastectomy breast reconstruction (12% versus 35%, P < 0.001). No significant ethnic or socio-economic differences were observed in rates of SNB or definitive local therapy. Conclusions: This study has demonstrated lower rates of breast conserving surgery and reconstructions in Maori compared with NZ European women, and highlight the need for future research to focus on understanding the reasons behind these findings.