Ethnic differences in timely adjuvant chemotherapy and radiation therapy for breast cancer in New Zealand: a cohort study

Abstract

BackgroundIndigenous and/or minority ethnic women are known to experience longer delays for treatment of breast cancer, which has been shown to contribute to ethnic inequities in breast cancer mortality. We examined factors associated with delay in adjuvant chemotherapy and radiotherapy for breast cancer, and its impact on the mortality inequity between Indigenous Māori and European women in New Zealand.MethodsAll women with newly diagnosed invasive non-metastatic breast cancer diagnosed during 1999–2012, who underwent adjuvant chemotherapy (n = 922) or radiation therapy (n = 996) as first adjuvant therapy after surgery were identified from the Waikato breast cancer register. Factors associated with delay in adjuvant chemotherapy (60-day threshold) and radiation therapy (90-day threshold) were analysed in univariate and multivariate models. Association between delay in adjuvant therapy and breast cancer mortality were explored in Cox regression models.ResultsOverall, 32.4% and 32.3% women experienced delays longer than thresholds for chemotherapy and radiotherapy, respectively. Higher proportions of Māori compared with NZ European women experienced delays longer than thresholds for adjuvant radiation therapy (39.8% vs. 30.6%, p = 0.045) and chemotherapy (37.3% vs. 30.5%, p = 0.103). Rural compared with urban residency, requiring a surgical re-excision and treatment in public compared with private hospitals were associated with significantly longer delays (p < 0.05) for adjuvant therapy in the multivariate model. Breast cancer mortality was significantly higher for women with a delay in initiating first adjuvant therapy (hazard ratio [HR] =1.45, 95% confidence interval [CI] 1.05-2.01). Mortality risks were higher for women with delays in chemotherapy (HR = 1.34, 95% CI 0.89-2.01) or radiation therapy (HR = 1.28, 95% CI 0.68-2.40), although these were statistically non-significant.ConclusionsIndigenous Māori women appeared to experience longer delays for adjuvant breast cancer treatment, which may be contributing towards higher breast cancer mortality in Māori compared with NZ European women. Measures to reduce delay in adjuvant therapy may reduce ethnic inequities and improve breast cancer outcomes for all women with breast cancer in New Zealand.

Variations in outcomes for Indigenous women with breast cancer in Australia: A systematic review

“…Additional approaches include cancer education programmes which support the role of Indigenous Health Workers (Le et al, 2013;Murphy et al, 2015;Smith, 2012;Whop et al, 2012;Zorbas & Elston, 2016), a key source of cancer information, health promotion and support for Indigenous patients undergoing cancer treatment (Bernardes et al, 2012). Studies from other countries have consistently attributed the well-documented poorer breast cancer survival (Dachs et al, 2008;DeSantis et al, 2014;Javid et al, 2014;Lawrenson et al, 2016;Nishri et al, 2015) in Indigenous populations to greater comorbidity burden, socioeconomic disadvantage, geographic location, cultural issues and variations in the timeliness, accessibility and quality of cancer services involving early detection, diagnosis and treatment (Javid et al, 2014;Kolahdooz et al, 2014;Lawrenson et al, 2016;Seneviratne et al, 2014;Tranberg et al, 2015). For example, Maori women are more likely to be diagnosed with advanced disease and experience delays in receiving treatment than non-Maori women in New Zealand (Lawrenson et al, 2016;Seneviratne et al, 2014) while in the United States, American Indians/Alaskan Native women are less likely to receive guideline concordant care than White women (Javid et al, 2014).…”

“…Studies from other countries have consistently attributed the well-documented poorer breast cancer survival (Dachs et al, 2008;DeSantis et al, 2014;Javid et al, 2014;Lawrenson et al, 2016;Nishri et al, 2015) in Indigenous populations to greater comorbidity burden, socioeconomic disadvantage, geographic location, cultural issues and variations in the timeliness, accessibility and quality of cancer services involving early detection, diagnosis and treatment (Javid et al, 2014;Kolahdooz et al, 2014;Lawrenson et al, 2016;Seneviratne et al, 2014;Tranberg et al, 2015). For example, Maori women are more likely to be diagnosed with advanced disease and experience delays in receiving treatment than non-Maori women in New Zealand (Lawrenson et al, 2016;Seneviratne et al, 2014) while in the United States, American Indians/Alaskan Native women are less likely to receive guideline concordant care than White women (Javid et al, 2014). The persistence of these variations among diverse Indigenous populations spanning a range of geographical settings and health care systems indicates both the likely similarities of the underlying issues and challenges involved in addressing them.…”

“…For example, Indigenous women from Canada (Nishri et al, 2015) and the United States (DeSantis et al, 2014;Javid et al, 2014) have poorer survival while having lower incidence rates than their non-Indigenous counterparts while Maori women have poorer survival (and higher incidence rates) than non-Maori women in New Zealand (Lawrenson et al, 2016). International studies have also consistently reported variations along the breast cancer continuum of care (such as screening, diagnosis and treatment) between Indigenous and non-Indigenous women (Javid et al, 2014;Kolahdooz et al, 2014;Lawrenson et al, 2016;Seneviratne et al, 2014;Tranberg et al, 2015).…”

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

“…[15][16][17] For example, Māori have been reported to have a lower likelihood of undergoing surgery for operable lung cancer, 15 and to experience longer delays for surgical treatment of breast and lung cancer compared with NZ European patients. [15][16][17][18] At present, limited data are available on quality or types of surgical treatment received by women with breast cancer in New Zealand 19 or possible ethnic differences in such treatment. We investigated differences in rates of BCS, SNB, post-mastectomy breast reconstruction and definitive local therapy for breast cancer by ethnicity among a cohort of women with invasive breast cancer in New Zealand.…”

A cohort study of ethnic differences in use of adjuvant chemotherapy and radiation therapy for breast cancer in New Zealand

“…Despite that, we did not observe a significant difference between Māori and NZ European women in the use of adjuvant chemotherapy for breast cancer, either in univariate or multivariate models. However, a previous analysis based on the WBCR found that Māori women were significantly more likely to experience longer delays for initiation of chemotherapy than for NZ European women [9]. Further, we have not analysed the use of recommended regimens of chemotherapy or rates of completion of chemotherapy in the present study.…”