HEALTH POLICY CSIRO PUBLISHING
Australian Health Review, 2014, 38, 134–141 http://dx.doi.org/10.1071/AH13080
Analysing risk factors for poorer breast cancer outcomes in residents of lower socioeconomic areas of Australia David Roder1,2,12 BDS, MPH, DDSc, Senior Population Health Advisor Helen M. Zorbas1 MBBS, FASBP, CEO James Kollias3,4,5 MBBS, FRACS, MD, Member (BQASC), Senior Consultant Surgeon (RAH), Senior Lecturer (UA)
Chris M. Pyke3,6,7 PhD, MBBS, FRACS, Member (BQASC), President (BreastSurgANZ), Breast Surgeon (MMC)
David Walters3,5,8,9 MBBS, DDU, FRACS, Member (BQASC), Clinical Director (BQA RACS), Senior Lecturer (UA), Consultant Surgeon (QEH)
Ian D. Campbell3,10 MB, ChB, FRACS, Member (BQASC) Corey Taylor8 BSc, GradDipPsych, Senior Analyst Fleur Webster11 BSc, MSc, MPH, Project Manager 1
Cancer Australia, Locked Bag 3, Strawberry Hills, NSW 2012, Australia. Email: [email protected] 2 School of Population Health, University of South Australia, Adelaide, SA 5001, Australia. Email: [email protected] 3 Breast Quality Audit Steering Committee, Breast Surgeons of Australia and New Zealand, Botany, NSW 1455, Australia. 4 Breast, Endocrine and Surgical Oncology Unit, Royal Adelaide Hospital, North Terrace, SA 5000, Australia. Email: [email protected] 5 University of Adelaide, North Terrace, SA 5005, Australia. 6 Breast Quality Audit, Breast Surgeons of Australia and New Zealand, Botany, NSW 1455, Australia. 7 Mater Medical Centre, 293 Vulture St, South Brisbane, QLD 4101, Australia. Email: [email protected] 8 Breast Quality Audit, Royal Australasian College of Surgeons, 199 Ward St, North Adelaide, SA 5006, Australia. Email: [email protected], [email protected] 9 The Queen Elizabeth Hospital, 28 Woodville Road, Woodville, SA 5011, Australia. 10 Waikato Clinical School, Faculty of Medical and Health Sciences, University of Auckland, Private Bag 3200, Hamilton, New Zealand. Email: [email protected] 11 Cancer Australia, Locked Bag 3, Strawberry Hills, NSW 2012, Australia. Email: fl[email protected] 12 Corresponding author. Email: [email protected]
Abstract Objective. To investigate patient, cancer and treatment factors associated with the residence of female breast cancer patients in lower socioeconomic areas of Australia to better understand factors that may contribute to their poorer cancer outcomes. Methods. Bivariable and multivariable analyses were performed using the Breast Quality Audit database of Breast Surgeons of Australia and New Zealand. Results. Multivariable regression indicated that patients from lower socioeconomic areas are more likely to live in more remote areas and to be treated at regional than major city centres. Although they appeared equally likely to be referred to surgeons from BreastScreen services as patients from higher socioeconomic areas, they were less likely to be referred as asymptomatic cases from other sources. In general, their cancer and treatment characteristics did not differ from those of women from higher socioeconomic areas, but ovarian ablation therapy was less common for these patients and bilateral synchronous lesions tended to be less frequent than for women from higher socioeconomic areas. Journal compilation AHHA 2014
www.publish.csiro.au/journals/ahr
Risk factors for poorer breast cancer outcomes
Australian Health Review
135
Conclusions. The results indicate that patients from lower socioeconomic areas are more likely to live in more remote districts and have their treatment in regional rather than major treatment centres. Their cancer and treatment characteristics appear to be similar to those of women from higher socioeconomic areas, although they are less likely to have ovarian ablation or to be referred as asymptomatic patients from sources other than BreastScreen. What is known about this topic? It is already known from Australian data that breast cancer outcomes are not as favourable for women from areas of socioeconomic disadvantage. The reasons for the poorer outcomes have not been understood. Studies in other countries have also found poorer outcomes in women from lower socioeconomic areas, and in some instances, have attributed this finding to more advanced stages of cancers at diagnosis and more limited treatment. The reasons are likely to vary with the country and health system characteristics. What does this paper add? The present study found that in Australia, women from lower socioeconomic areas do not have more advanced cancers at diagnosis, nor, in general, other cancer features that would predispose them to poorer outcomes. The standout differences were that they tended more to live in areas that were more remote from specialist metropolitan centres and were more likely to be treated in regional settings where prior research has indicated poorer outcomes. The reasons for these poorer outcomes are not known but may include lower levels of surgical specialisation, less access to specialised adjunctive services, and less involvement with multidisciplinary teams. Women from lower socioeconomic areas also appeared more likely to attend lower case load surgeons. Little difference was evident in the type of clinical care received, although women from lower socioeconomic areas were less likely to be asymptomatic referrals from other clinical settings (excluding BreastScreen). What are the implications for practitioners? Results suggest that poorer outcomes in women from lower socioeconomic areas in Australia may have less to do with the characteristics of their breast cancers or treatment modalities and more to do with health system features, such as access to specialist centres. This study highlights the importance of demographic and health system features as potentially key factors in service outcomes. Health system research should be strengthened in Australia to augment biomedical and clinical research, with a view to best meeting service needs of all sectors of the population. Received 6 June 2013, accepted 22 October 2013, published online 8 April 2014
Introduction Low socioeconomic status is predictive of poorer health in many populations.1–6 Australian burden of disease data indicate that 19% more disability adjusted years of life are lost by residents of areas in the lowest than highest socioeconomic quintile.4 The need to address the health needs of lower socioeconomic groups is stated in Australian health policy,7 health research priorities of the National Health and Medical Research Council8 and as a health surveillance priority.9 Socioeconomic disadvantage applies to cancer outcomes as it does to other health outcomes.10,11 For all cancers combined (excluding non-melanoma skin cancers, which are not recorded by cancer registries), the risk of cancer death in the first 5 years from diagnosis for cases diagnosed in 2006–10 was 26% higher in the lowest than highest socioeconomic quintile.10 For female breast cancer, the corresponding risk was 29% higher,10 whereas it was 50% higher for cervical cancer, 49% higher for prostate cancer, 20% higher for non-Hodgkin’s lymphoma and 16% higher for colorectal cancer. Similar trends applied for outcomes of cancers diagnosed in 2000–04, with an elevation in risk of death of 27% for all cancers combined in the lowest compared with highest quintile and a higher 39% elevation for breast cancer death.11 Similar trends for poorer cancer outcomes in lower socioeconomic groups have been reported for many countries and regions,12 including North America,13,14 Scandinavia,15,16 Europe and New Zealand.12,17,18 Differences in stage at diagnosis are often reported to have contributed to these differences,12–14,18 but additional factors have also been implicated, including higher levels of comorbidity,19 lower levels of social support,20
differences in treatment12,21 and variations in service access, size of treatment centre and other health service characteristics.12 Lower 5-year cancer survival rates have been reported among Aboriginal and Torres Strait Islander compared with other Australian women for all cancers combined in Australian studies,22–24 including studies in South Australia (SA; 40% vs 57% in 1977–2007) and New South Wales (NSW; 53% vs 65% in 1999–2007).23,24 For female breast cancer, corresponding survival rates for Aboriginal and Torres Strait Islander compared with other Australian women were 61% versus 80%, respectively, for SA and 79% versus 88%, respectively, for NSW.23,24 Meanwhile, Australian data for 2002–06 indicate lower survival rates for breast cancer cases from all causes of death for Aboriginal and Torres Strait Islander women compared with other women (65% vs 88%, respectively).25 Corresponding survival rates for 2006–10 were 69% for Aboriginal and Torres Strait Islander women and 83% for other women.26 It is likely, from these data, that poorer outcomes in Aboriginal and Torres Strait Islander patients and their elevated proportional representation in lower socioeconomic areas would have contributed to the higher case fatality rates in these areas.27,28 Poorer outcomes from breast cancer in Aboriginal and Torres Strait Islander women have been attributed to lower screening coverage, raised levels of comorbidity and poorer service access.22,23,27 In the present study we investigated the comparative distribution of socioeconomic status of residential area by those sociodemographic, cancer and treatment characteristics that have been found to relate to poorer breast cancer outcomes in Australia.29–31 Our aim was to better understand factors that underlie socioeconomic disadvantage and identify opportunities
136
Australian Health Review
to reduce disparities. The data are for women with early invasive breast cancers treated by Australian breast surgeons participating in the Breast Surgeons of Australia and New Zealand National Breast Cancer Audit. Opportunities suggested by the results for reducing disadvantage are discussed, along with research implications. Although breast cancers covered by the Audit are not selected to be representative of all early breast cancers in Australia, they comprise the majority and appear to be broadly representative in their survival outcomes.29 In addition, differences in survival rates by conventional prognostic factors, such as tumour size, grade, nodal status and oestrogen receptor status, accord with differences expected from population-based studies, indicating that the Audit data may be a credible basis for population inference.29 Methods Ethics approval for the present study was obtained from the research ethics committee of the Royal Australasian College of Surgeons. Data for early invasive female breast cancers treated by Australian breast surgeons participating in the Breast Surgeons of Australia and New Zealand Breast Quality Audit from approximately 1998 to 2010 were analysed (i.e. C50 ICD-O-3 topography code and a behaviour code of 3).29 Early breast cancer was defined as cancers not more than 5 cm centimetres in diameter without fixed nodes.32 Numbers of patients covered by the Audit have increased progressively and now represent approximately 60% of women diagnosed with early breast cancer in Australia.29 The Audit did not include residential address in its minimum dataset throughout the study period. Data were analysed for 30 299 early invasive breast cancers diagnosed in Australian women for whom residential addresses were recorded, using postcodes to infer socioeconomic status of residential area, which was the principal characteristic of interest.33 Residential areas were classified according to socioeconomic quintile of residential postcode at diagnosis using the SocioEconomic Indexes for Areas Index of Relative Socioeconomic Disadvantage.10,11,33 This was done using data from the 2006 census and categorising to gain similar numbers on an ordinal quintile scale (i.e. from high to mid-high, mid, mid-low, and low quintile). Variables investigated as predictors of socioeconomic quintile included: (1) patient factors, namely age at diagnosis (
Australian Health Review, 2014, 38, 134–141 http://dx.doi.org/10.1071/AH13080
Analysing risk factors for poorer breast cancer outcomes in residents of lower socioeconomic areas of Australia David Roder1,2,12 BDS, MPH, DDSc, Senior Population Health Advisor Helen M. Zorbas1 MBBS, FASBP, CEO James Kollias3,4,5 MBBS, FRACS, MD, Member (BQASC), Senior Consultant Surgeon (RAH), Senior Lecturer (UA)
Chris M. Pyke3,6,7 PhD, MBBS, FRACS, Member (BQASC), President (BreastSurgANZ), Breast Surgeon (MMC)
David Walters3,5,8,9 MBBS, DDU, FRACS, Member (BQASC), Clinical Director (BQA RACS), Senior Lecturer (UA), Consultant Surgeon (QEH)
Ian D. Campbell3,10 MB, ChB, FRACS, Member (BQASC) Corey Taylor8 BSc, GradDipPsych, Senior Analyst Fleur Webster11 BSc, MSc, MPH, Project Manager 1
Cancer Australia, Locked Bag 3, Strawberry Hills, NSW 2012, Australia. Email: [email protected] 2 School of Population Health, University of South Australia, Adelaide, SA 5001, Australia. Email: [email protected] 3 Breast Quality Audit Steering Committee, Breast Surgeons of Australia and New Zealand, Botany, NSW 1455, Australia. 4 Breast, Endocrine and Surgical Oncology Unit, Royal Adelaide Hospital, North Terrace, SA 5000, Australia. Email: [email protected] 5 University of Adelaide, North Terrace, SA 5005, Australia. 6 Breast Quality Audit, Breast Surgeons of Australia and New Zealand, Botany, NSW 1455, Australia. 7 Mater Medical Centre, 293 Vulture St, South Brisbane, QLD 4101, Australia. Email: [email protected] 8 Breast Quality Audit, Royal Australasian College of Surgeons, 199 Ward St, North Adelaide, SA 5006, Australia. Email: [email protected], [email protected] 9 The Queen Elizabeth Hospital, 28 Woodville Road, Woodville, SA 5011, Australia. 10 Waikato Clinical School, Faculty of Medical and Health Sciences, University of Auckland, Private Bag 3200, Hamilton, New Zealand. Email: [email protected] 11 Cancer Australia, Locked Bag 3, Strawberry Hills, NSW 2012, Australia. Email: fl[email protected] 12 Corresponding author. Email: [email protected]
Abstract Objective. To investigate patient, cancer and treatment factors associated with the residence of female breast cancer patients in lower socioeconomic areas of Australia to better understand factors that may contribute to their poorer cancer outcomes. Methods. Bivariable and multivariable analyses were performed using the Breast Quality Audit database of Breast Surgeons of Australia and New Zealand. Results. Multivariable regression indicated that patients from lower socioeconomic areas are more likely to live in more remote areas and to be treated at regional than major city centres. Although they appeared equally likely to be referred to surgeons from BreastScreen services as patients from higher socioeconomic areas, they were less likely to be referred as asymptomatic cases from other sources. In general, their cancer and treatment characteristics did not differ from those of women from higher socioeconomic areas, but ovarian ablation therapy was less common for these patients and bilateral synchronous lesions tended to be less frequent than for women from higher socioeconomic areas. Journal compilation AHHA 2014
www.publish.csiro.au/journals/ahr
Risk factors for poorer breast cancer outcomes
Australian Health Review
135
Conclusions. The results indicate that patients from lower socioeconomic areas are more likely to live in more remote districts and have their treatment in regional rather than major treatment centres. Their cancer and treatment characteristics appear to be similar to those of women from higher socioeconomic areas, although they are less likely to have ovarian ablation or to be referred as asymptomatic patients from sources other than BreastScreen. What is known about this topic? It is already known from Australian data that breast cancer outcomes are not as favourable for women from areas of socioeconomic disadvantage. The reasons for the poorer outcomes have not been understood. Studies in other countries have also found poorer outcomes in women from lower socioeconomic areas, and in some instances, have attributed this finding to more advanced stages of cancers at diagnosis and more limited treatment. The reasons are likely to vary with the country and health system characteristics. What does this paper add? The present study found that in Australia, women from lower socioeconomic areas do not have more advanced cancers at diagnosis, nor, in general, other cancer features that would predispose them to poorer outcomes. The standout differences were that they tended more to live in areas that were more remote from specialist metropolitan centres and were more likely to be treated in regional settings where prior research has indicated poorer outcomes. The reasons for these poorer outcomes are not known but may include lower levels of surgical specialisation, less access to specialised adjunctive services, and less involvement with multidisciplinary teams. Women from lower socioeconomic areas also appeared more likely to attend lower case load surgeons. Little difference was evident in the type of clinical care received, although women from lower socioeconomic areas were less likely to be asymptomatic referrals from other clinical settings (excluding BreastScreen). What are the implications for practitioners? Results suggest that poorer outcomes in women from lower socioeconomic areas in Australia may have less to do with the characteristics of their breast cancers or treatment modalities and more to do with health system features, such as access to specialist centres. This study highlights the importance of demographic and health system features as potentially key factors in service outcomes. Health system research should be strengthened in Australia to augment biomedical and clinical research, with a view to best meeting service needs of all sectors of the population. Received 6 June 2013, accepted 22 October 2013, published online 8 April 2014
Introduction Low socioeconomic status is predictive of poorer health in many populations.1–6 Australian burden of disease data indicate that 19% more disability adjusted years of life are lost by residents of areas in the lowest than highest socioeconomic quintile.4 The need to address the health needs of lower socioeconomic groups is stated in Australian health policy,7 health research priorities of the National Health and Medical Research Council8 and as a health surveillance priority.9 Socioeconomic disadvantage applies to cancer outcomes as it does to other health outcomes.10,11 For all cancers combined (excluding non-melanoma skin cancers, which are not recorded by cancer registries), the risk of cancer death in the first 5 years from diagnosis for cases diagnosed in 2006–10 was 26% higher in the lowest than highest socioeconomic quintile.10 For female breast cancer, the corresponding risk was 29% higher,10 whereas it was 50% higher for cervical cancer, 49% higher for prostate cancer, 20% higher for non-Hodgkin’s lymphoma and 16% higher for colorectal cancer. Similar trends applied for outcomes of cancers diagnosed in 2000–04, with an elevation in risk of death of 27% for all cancers combined in the lowest compared with highest quintile and a higher 39% elevation for breast cancer death.11 Similar trends for poorer cancer outcomes in lower socioeconomic groups have been reported for many countries and regions,12 including North America,13,14 Scandinavia,15,16 Europe and New Zealand.12,17,18 Differences in stage at diagnosis are often reported to have contributed to these differences,12–14,18 but additional factors have also been implicated, including higher levels of comorbidity,19 lower levels of social support,20
differences in treatment12,21 and variations in service access, size of treatment centre and other health service characteristics.12 Lower 5-year cancer survival rates have been reported among Aboriginal and Torres Strait Islander compared with other Australian women for all cancers combined in Australian studies,22–24 including studies in South Australia (SA; 40% vs 57% in 1977–2007) and New South Wales (NSW; 53% vs 65% in 1999–2007).23,24 For female breast cancer, corresponding survival rates for Aboriginal and Torres Strait Islander compared with other Australian women were 61% versus 80%, respectively, for SA and 79% versus 88%, respectively, for NSW.23,24 Meanwhile, Australian data for 2002–06 indicate lower survival rates for breast cancer cases from all causes of death for Aboriginal and Torres Strait Islander women compared with other women (65% vs 88%, respectively).25 Corresponding survival rates for 2006–10 were 69% for Aboriginal and Torres Strait Islander women and 83% for other women.26 It is likely, from these data, that poorer outcomes in Aboriginal and Torres Strait Islander patients and their elevated proportional representation in lower socioeconomic areas would have contributed to the higher case fatality rates in these areas.27,28 Poorer outcomes from breast cancer in Aboriginal and Torres Strait Islander women have been attributed to lower screening coverage, raised levels of comorbidity and poorer service access.22,23,27 In the present study we investigated the comparative distribution of socioeconomic status of residential area by those sociodemographic, cancer and treatment characteristics that have been found to relate to poorer breast cancer outcomes in Australia.29–31 Our aim was to better understand factors that underlie socioeconomic disadvantage and identify opportunities
136
Australian Health Review
to reduce disparities. The data are for women with early invasive breast cancers treated by Australian breast surgeons participating in the Breast Surgeons of Australia and New Zealand National Breast Cancer Audit. Opportunities suggested by the results for reducing disadvantage are discussed, along with research implications. Although breast cancers covered by the Audit are not selected to be representative of all early breast cancers in Australia, they comprise the majority and appear to be broadly representative in their survival outcomes.29 In addition, differences in survival rates by conventional prognostic factors, such as tumour size, grade, nodal status and oestrogen receptor status, accord with differences expected from population-based studies, indicating that the Audit data may be a credible basis for population inference.29 Methods Ethics approval for the present study was obtained from the research ethics committee of the Royal Australasian College of Surgeons. Data for early invasive female breast cancers treated by Australian breast surgeons participating in the Breast Surgeons of Australia and New Zealand Breast Quality Audit from approximately 1998 to 2010 were analysed (i.e. C50 ICD-O-3 topography code and a behaviour code of 3).29 Early breast cancer was defined as cancers not more than 5 cm centimetres in diameter without fixed nodes.32 Numbers of patients covered by the Audit have increased progressively and now represent approximately 60% of women diagnosed with early breast cancer in Australia.29 The Audit did not include residential address in its minimum dataset throughout the study period. Data were analysed for 30 299 early invasive breast cancers diagnosed in Australian women for whom residential addresses were recorded, using postcodes to infer socioeconomic status of residential area, which was the principal characteristic of interest.33 Residential areas were classified according to socioeconomic quintile of residential postcode at diagnosis using the SocioEconomic Indexes for Areas Index of Relative Socioeconomic Disadvantage.10,11,33 This was done using data from the 2006 census and categorising to gain similar numbers on an ordinal quintile scale (i.e. from high to mid-high, mid, mid-low, and low quintile). Variables investigated as predictors of socioeconomic quintile included: (1) patient factors, namely age at diagnosis (
