Disparities in breast screening, stage at diagnosis, cancer treatment and the subsequent risk of cancer death: a retrospective, matched cohort of aboriginal and non-aboriginal women with breast cancer

Abstract

Background Australia’s Aboriginal and Torres Strait Islander women have poorer survival and twice the disease burden from breast cancer compared to other Australian women. These disparities are influenced, but not fully explained, by more diagnoses at later stages. Incorporating breast screening, hospital and out of hospital treatment and cancer registry records into a person-linked data system can improve our understanding of breast cancer outcomes. We focussed one such system on a population-based cohort of Aboriginal women in South Australia diagnosed with breast cancer and a matched cohort of non-Aboriginal women with breast cancer. We quantify Aboriginal and non-Aboriginal women’s contact with publicly funded screening mammograms; quantify exposure to a selection of cancer treatment modalities; then assess the relationship between screening, treatment and the subsequent risk of breast cancer death. Methods Breast cancers registered among Aboriginal women in South Australia in 1990–2010 ( N = 77) were matched with a random selection of non-Aboriginal women by birth and diagnostic year, then linked to screening records, and treatment 2 months before and 13 months after diagnosis. Competing risk regression summarised associations of Aboriginality, breast screening, cancer stage and treatment with risk of breast cancer death. Results Aboriginal women were less likely to have breast screening (OR = 0.37, 95%CIs 0.19–0.73); systemic therapies (OR = 0.49, 95%CIs 0.24–0.97); and, surgical intervention (OR = 0.35, 95%CIs 0.15–0.83). Where surgery occurred, mastectomy was more common among Aboriginal women (OR = 2.58, 1.22–5.46). Each of these factors influenced the risk of cancer death, reported as sub-hazard ratios (SHR). Regional spread disease (SHR = 34.23 95%CIs 6.76–13.40) and distant spread (SHR = 49.67 95%CIs 6.79–363.51) carried more risk than localised disease (Reference SHR = 1). Breast screening reduced the risk (SHR = 0.07 95%CIs 0.01–0.83). So too did receipt of systemic therapy (SHR = 0.06 95%CIs 0.01–0.41) and surgical treatments (SHR = 0.17 95%CIs 0.04–0.74). In the presence of adjustment for these factors, Aboriginality did not further explain the risk of breast cancer death. Conclusion Under-exposure to screening and treatment of Aboriginal women with breast cancers in South Australia contributed to excess cancer deaths. Improved access, utilisation and quality of effective treatments is needed to improve survival after breast cancer diagnosis.

Choosing Wisely in radiation therapy for breast cancer: Time lag in adoption of hypofractionated radiation therapy in Victoria

“…On patient‐level analyses, Laucis et al reported that black patients were less likely to be treated with HFRT compared to white patients 14 . In Australia, the population that have been consistently reported to be disadvantaged in cancer care are the Aboriginal and Torres Straits Islander (ATSI) 22 . However, data on ATSI has been inconsistently reported and collected in the Victorian administrative dataset to allow evaluation of such disparities.…”

Cancer treatment and the risk of cancer death among Aboriginal and non-Aboriginal South Australians: analysis of a matched cohort study

“…Of those 777 cases, none were described as Torres Strait Islanders, therefore this cohort is referred to as the Aboriginal cohort. Each case in the Aboriginal cohort was matched with a cancer case involving a non-Indigenous person on the basis of: gender; birth and diagnosis year [39], and primary cancer site.…”

“…As the propensity to self-report as Aboriginal or Torres Strait Islander can vary across settings and time [44], it can be a source of misclassification bias [45]. We optimised the specificity of Aboriginal and Torres Strait Islander status by erring towards non-Indigenous status when uncertainty existed after cross-referencing SACR records against other linked datasets in the study [39], and following additional hand searching [35]. Some misclassification of Indigenous status may have resulted as a consequence of this practice, but we believe the low proportion of non-Indigenous cases that would have been misclassified would have had little effect on comparisons by Indigenous status.…”

Occurrence and timely management of problems requiring prompt intervention among Indigenous compared with non-Indigenous Australian palliative care patients: a multijurisdictional cohort study

“…Indigenous Australians experience disparities in health service provision and outcomes across their lives, and this is likely to occur within their journey with a life-limiting illness. 30 31 In the case of cancer (the principal diagnosis of the majority of patients receiving specialist palliative care), Indigenous Australians have lower uptake of screening, 32 and they commonly experience substantial delays in diagnosis. 33 34 Additionally, they have more limited access to definitive treatments, 32 35 have lower uptake of hospitalisations 36 and frequently have unmet supportive care needs.…”

“… 30 31 In the case of cancer (the principal diagnosis of the majority of patients receiving specialist palliative care), Indigenous Australians have lower uptake of screening, 32 and they commonly experience substantial delays in diagnosis. 33 34 Additionally, they have more limited access to definitive treatments, 32 35 have lower uptake of hospitalisations 36 and frequently have unmet supportive care needs. 37 A far lower proportion of Indigenous compared with non-Indigenous patients receive specialist palliative care at the end of life.…”