Connect
MJA
MJA

Comparing colorectal cancer treatment and survival for Aboriginal and non-Aboriginal people in New South Wales

Kristie Weir, Rajah Supramaniam, Alison Gibberd, Anthony Dillon, Bruce K Armstrong and Dianne L O'Connell
Med J Aust 2016; 204 (4): 156. || doi: 10.5694/mja15.01153
Published online: 7 March 2016

Abstract

Objectives: Our aim was to compare surgical treatment rates and survival rates for Aboriginal and non-Aboriginal people in New South Wales with colorectal cancer, and to describe the medical treatment received by a sample of Aboriginal people with colorectal cancer.

Design, setting and participants: All people diagnosed with colorectal cancer in NSW during 2001–2007 were identified and their cancer registry records linked to hospital admissions data and death records. A medical records audit of a sample of Aboriginal people diagnosed with colorectal cancer during 2000–2011 was also conducted.

Main outcome measures: Cause-specific survival, odds of surgical treatment, and the proportions of people receiving adjuvant treatments.

Results: Of 29 777 eligible colorectal cancer cases, 278 (0.9%) involved Aboriginal people. Similar proportions of Aboriginal (76%) and non-Aboriginal (79%) people had undergone surgical treatment. Colorectal cancer-specific survival was similar for Aboriginal and non-Aboriginal people up to 18 months after diagnosis, but 5 years post-diagnosis the risk of death for Aboriginal people who had had surgical treatment was 68% higher than for non-Aboriginal people (adjusted hazards ratio, 1.68; 95% CI, 1.32–2.09). Of 145 Aboriginal people with colorectal cancer identified by the medical records audit, 117 (81%) had undergone surgery, and 56 (48%) had also received adjuvant chemotherapy and/or radiotherapy.

Conclusions: Aboriginal people with colorectal cancer had poorer survival rates than non-Aboriginal people, although rates of surgical treatment, complications and follow-up colonoscopy were similar. More work is needed to identify and understand why outcomes for Aboriginal people with colorectal cancer are different from those of other New South Wales residents.

Previous studies of colorectal cancer survival in New South Wales,1 South Australia,2 Queensland3 and the Northern Territory4 have found that survival tended to be poorer for Aboriginal than for non-Aboriginal people. These studies identified disease factors and less access to primary and follow-up treatments as possible reasons for the survival disparities.

The recommended treatment for colorectal cancer is generally surgery combined with adjuvant chemotherapy or radiotherapy, depending on the cancer type and extent of disease.5,6 Treatment guidelines also highlight the importance of post-surgical follow-up care, as one in three people will die from disease recurrence after initial treatment.3 However, the Australian guidelines available during the study period for this article did not describe a specific protocol for follow-up care.5,6

Our main aim was to compare the treatment and survival rates for Aboriginal and non-Aboriginal people diagnosed with colorectal cancer in NSW using routinely collected, population-based linked data. We also estimated the proportions of a sample of NSW Aboriginal people with colorectal cancer who received chemotherapy or radiotherapy.

We respectfully use the descriptor “Aboriginal people” throughout this report to refer to the original people of Australia and their descendants.

Methods

We analysed two different linked datasets, both of which have been described previously:7,8 data from the NSW Population-wide Study (2001–2007) and data from the Patterns of Care study (2001–2011). The NSW Population-wide Study data comprised incident cancer cases linked with hospital separations data and death records; the Patterns of Care study data comprised information collected in an audit of medical records of Aboriginal people with colorectal cancer (diagnosed during the period 2000–2011) linked to incident cancer cases, hospital separations data and death records. People were eligible for inclusion in the study if they were NSW residents diagnosed with primary colorectal cancer (International Classification of Diseases, revision 10, topography codes C18–C20, and International Classification of Diseases for Oncology morphology codes ending /3) and 18 years or older.

NSW Population-wide Study

Data sources

Demographic and disease information for all eligible people diagnosed with colorectal cancer during the period 2001–2007 was obtained from the NSW Central Cancer Registry. Cases were matched by the Centre for Health Record Linkage (CHeReL) with inpatient records from the NSW Admitted Patient Data Collection (APDC), death records from the NSW Registry of Births, Deaths and Marriages, and coded causes of death in Australian Bureau of Statistics (ABS) data. A person was determined to be Aboriginal if they were identified as Aboriginal in any of their linked records.

Variables for analysis

Information from the Clinical Cancer Registry included month and year of diagnosis, age at diagnosis, and spread of disease at diagnosis (reported as localised, regional, distant, or unknown). Cancers were also categorised by site (colon, rectum, or rectosigmoid junction).

Using the Accessibility and Remoteness Index for Australia (ARIA+),9 the Local Government Area (LGA) of residence of participants at diagnosis was categorised as major city, inner regional or rural (“rural” comprising outer regional, remote, and very remote). The LGA of residence at diagnosis was also assigned to a quintile of socio-economic disadvantage according to the Index of Relative Socio-economic Advantage and Disadvantage.10

We restricted our analysis to surgical treatment, both planned and emergency, as other studies have shown a high concordance between surgery recorded in the APDC and clinical audits of medical records.11

Comorbidities were any non-cancer conditions described in the Charlson Comorbidity Index12 that were recorded for any hospital admission in the 12 months before and the 6 months after diagnosis with colorectal cancer. People not admitted to hospital during this period were recorded as having “no comorbidity information available”.

Statistical methods

Analyses were performed with SAS 9.2 (SAS Institute) and R 3.0.0 (R Foundation for Statistical Computing). We used Pearson χ2 tests to compare demographic data for Aboriginal and non-Aboriginal people. Logistic regression was initially used to compare the unadjusted odds of Aboriginal and non-Aboriginal people having surgery within 12 months of diagnosis. We then fitted a multivariable model by adding the variables sex, age at diagnosis, year of diagnosis, site of cancer, spread of disease, comorbidities, socio-economic disadvantage, and place of residence.

Colorectal cancer-specific survival was analysed with cumulative incidence curves and Cox regression models. Follow-up was censored at 31 December 2008 for all people whose deaths were not recorded. People who died from other causes were censored at the date of death. Variables were entered into the model described above, with the addition of surgical treatment as a variable. We included the statistically significant interaction between surgery and Aboriginal status in the final model. The proportional hazards assumption for Aboriginal status was satisfied in the final model.13

The probabilities of having a colonoscopy between 3 months and 3 years post-surgery were estimated for Aboriginal and non-Aboriginal people with localised or regional spread at diagnosis using cumulative incidence curves, with the competing risk of death without a colonoscopy included in the analysis.14

Patterns of Care (POC) study

Variables for analysis

The information collected from 23 public hospitals and three clinical cancer registries included age, sex, year of diagnosis, spread of disease, postcode of residence, and comorbidities. Postcode of residence was used to assign quintiles of socio-economic disadvantage10,15 and ARIA+ category.9 Treatment information (surgery, chemotherapy and radiotherapy) included start and end dates, and reasons for incomplete or no treatment. We merged data for people who attended several hospitals, and data were checked for appropriate ranges of responses and any anomalies.

Ethics approval

The collection of the POC data was approved by the Royal Prince Alfred Hospital Human Research Ethics Committee (reference, 08/RPAH/374) and the Aboriginal Health and Medical Research Council (AH&MRC; reference, 636/08). Local Regional Governance Offices granted site-specific approval for data collection in participating hospitals and clinical cancer registries. Linkage of the POC data to the population datasets was approved by the NSW Population and Health Services Research Ethics Committee (reference, 2011/04/319) and the AH&MRC Ethics Committee (reference, 791/11). Analysis of the NSW population data was approved by the NSW Population and Health Services Research Ethics Committee (reference, 2006/04/004) and the AH&MRC committee (reference, 550/06).

Results

NSW Population-wide Study

Characteristics

During 2001–2007, 30 448 people were diagnosed with primary colorectal cancer in NSW. We excluded 281 people notified to the Clinical Cancer Registry by death certificate only (0.9% of all cases) and 390 people (1.3%) with no matching hospital inpatient record (Box 1). This resulted in a final sample of 29 777 people, of whom 278 (0.9%) were identified as Aboriginal.

Compared with non-Aboriginal people (median age, 71 years), the Aboriginal people in our study were younger (median age, 64 years), more likely to live outside major cities and in socio-economically disadvantaged areas, and to have diabetes and chronic pulmonary disease at the time of their cancer diagnosis. Cancer site, disease spread at diagnosis, and the proportions of men and women were similar for Aboriginal and non-Aboriginal people (Box 2).

Surgical treatment

Aboriginal and non-Aboriginal people had the same median time to surgical treatment (13 days; interquartile range [IQR] for non-Aboriginal people, 1–33 days; IQR for Aboriginal people, 2–28 days), and the proportions who had received surgical treatment within 12 months of diagnosis were also similar (76% and 79% respectively) (Box 2). After accounting for differences in sex, age at diagnosis, year of diagnosis, spread of disease at diagnosis, cancer site, place of residence at diagnosis, comorbidities, and socio-economic disadvantage, there was no significant difference in the likelihood of Aboriginal and non-Aboriginal people receiving surgical treatment (odds ratio for Aboriginal people receiving surgical treatment, 0.93; 95% confidence interval [CI], 0.68–1.27).

Survival

For the first 18 months after diagnosis, mortality among people with colorectal cancer was similar for Aboriginal and non-Aboriginal people (Box 3). However, from 18 months a difference between the two groups was apparent, and by 5 years after diagnosis the cumulative mortality from colorectal cancer was 43% for Aboriginal people, compared with 33% for non-Aboriginal people (Box 4).

The unadjusted risk of death from colorectal cancer for Aboriginal people was 33% greater than for non-Aboriginal people (hazard ratio [HR], 1.33; 95% CI, 1.09–1.61; P = 0.006). For those who did not have surgical treatment, the risk of death after adjusting for sex, age at diagnosis, year of diagnosis, spread of disease, site of cancer, comorbidities, socio-economic disadvantage, and place of residence, was similar for Aboriginal and non-Aboriginal people (HR, 1.05; 95% CI, 0.70–1.50). However, the adjusted risk of death among those who had received surgical treatment was 68% greater for Aboriginal than for non-Aboriginal people (HR, 1.68; 95% CI, 1.32–2.09) (Box 4). The risk of death for those who had had surgical treatment was similar for Aboriginal and non-Aboriginal people during the first 18 months after diagnosis (Box 5).

Aboriginal and non-Aboriginal people who had received surgical treatment had similar rates of emergency surgery (Box 2) and median lengths of stay in hospital (10 days). During the admission for surgical treatment, 15% of Aboriginal and 13% of non-Aboriginal people had post-surgical complications (difference, 2%; 95% CI, −2.7% to 6.9%); 2% of Aboriginal people and 3% of non-Aboriginal people died within 30 days of surgery (difference, −1%; 95% CI, –2.9% to 1.2%).

By 18 months after surgery, 45% of Aboriginal people had had a colonoscopy, compared with 55% of non-Aboriginal people (Box 6). However, the proportions after 3 years were 59% for Aboriginal people and 65% for non-Aboriginal people.

Patterns of Care study

Characteristics

Compared with the Aboriginal people recorded in the NSW Population-wide Study data, the 145 Aboriginal people with colorectal cancer whose medical records we reviewed were, on average, younger at diagnosis (median age, 61 years), more likely to live outside major cities, and less likely to have been diagnosed with rectal cancer (Box 2, Box 7). As the two samples overlapped, formal statistical comparisons could not be made.

Surgical treatment

Overall, 117 people (81%) had received surgical treatment within 12 months of diagnosis. The proportions of people receiving surgical treatment were 82% for people with colon cancer, 77% for people with rectal cancer, and 82% for people with cancer in the rectosigmoid junction.

Adjuvant chemotherapy and radiotherapy

Of those who received surgical treatment, 48% also received adjuvant chemotherapy and/or radiotherapy. Of the 56 people with regional spread of disease, ten (18%) did not receive adjuvant treatment. Reasons for not receiving adjuvant treatment included the choice of the patient, and advice from their doctor that the associated harms would probably outweigh the benefits. Of the 42 people with localised disease who had surgery, three (7%) also received adjuvant treatment.

Discussion

We found that the 5-year survival rate was lower for Aboriginal people in NSW with colorectal cancer than for non-Aboriginal people, despite their being, on average, younger at diagnosis and having a similar spread of disease, similar surgical treatment rates, and similar times to surgery. This disparity in survival was evident from 18 months after diagnosis, and was largely confined to those who had received surgical treatment, although we found no differences in post-surgical complications or in the 3-year rates of follow-up colonoscopy. We also found that the Aboriginal people in our POC data received adjuvant chemotherapy and radiotherapy at levels similar to those reported in a previous population-based survey of colorectal cancer care in NSW16,17 and in a more recent analysis of node-positive cases.18

The survival disparity was only observable from 18 months post-surgery, suggesting that Aboriginal people may have had higher rates of disease recurrence, recurrence that was not identified because of poorer follow-up, lower rates of follow-up colonoscopies to detect new tumours, or lower rates of adjuvant therapies. However, we observed no significant differences (when compared with non-Aboriginal people) in planned or emergency post-surgical admissions, or in the receipt of adjuvant therapies, and no differences in the rates of colonoscopy up to 3 years after surgery. Alternatively, the observed difference in mortality between Aboriginal and non-Aboriginal people may be due to differences in the proportions of people with microsatellite unstable tumours or to other tumour characteristics; information in this regard, however, was not available for this study.

As we found that Aboriginal people with colorectal cancer had poorer survival outcomes than non-Aboriginal people, but no obvious differences in the treatment or follow-up they received, it is plausible that small differences and delays along the treatment pathway, perhaps caused by cultural barriers, contribute to lower survival. This has been found for Māori people accessing chemotherapy for stage III colon cancer in New Zealand.19

That Aboriginal people with cancer generally have poorer survival outcomes than non-Aboriginal people with cancer has been reported by other Australian studies, with health care access and cultural differences generally being identified as factors underlying this disparity.1-3,7 The Cancer Institute NSW recently reported that Aboriginal people had a 63% increased risk of death from bowel cancer after adjusting for age and year of diagnosis and for spread of disease;1 this report did not, however, adjust for comorbidities, surgical treatment, sex, place of residence, socio-economic disadvantage, or cancer site. Similarly, a South Australian study reported that Aboriginal people with bowel cancer had a 5-year survival rate of 34.1%, compared with 56.1% for non-Aboriginal people.2 An older study of cancer survival in the Northern Territory4 attributed the higher risk of death for Aboriginal people to their having poorer access to quality health services, perhaps because of a lack of “social proximity” to these services.

Qualitative research on the health care received by Aboriginal people with cancer20 has identified several cultural barriers that may contribute to delays in their accessing mainstream health services (such as follow-up colonoscopies), including feelings of fatalism, shame, and embarrassment about colorectal cancer. More recent studies have identified lower health literacy,21 feelings of social exclusion when in hospital,22 and health services not fully responding to cultural differences as potential barriers to optimal care for Aboriginal people.23

Our analysis of the NSW Population-wide Study data is the first to include detailed information about the influence of comorbidities on surgical treatment and survival for Aboriginal people with colorectal cancer. However, it does have some limitations. First, the identification of Aboriginal people is dependent on correct recording of their status in the source datasets. As 98% of the Australian population is non-Aboriginal, the chance of positive misclassification is low, and we attempted to minimise under-identification of Aboriginal people by accepting any record of Aboriginal status in any linked record, including admissions not related to cancer. Second, using ABS information on deaths to identify Aboriginal people may have biased our survival results. In a sensitivity analysis we found, however, that using the APDC alone to determine Aboriginal status reduced the proportion of Aboriginal people who died from colorectal cancer within 5 years of diagnosis from 43% to 37%, and the overall survival patterns were similar to those reported here. Other potential sources of error include the possibility that we did not fully account for potential confounding factors that might contribute to the observed differences in survival, and measurement errors in the recording of covariates, such as comorbidities and spread of disease at the time of diagnosis. In addition, socio-economic disadvantage and place of residence were determined at the LGA level, and may thus be a source of measurement error. Further, although the POC data included more detailed information on the medical treatment of Aboriginal people with colorectal cancer than any other published study, the representativeness of the results may be limited, as we included only people from 23 hospitals and three clinical cancer registries.

Conclusion

Aboriginal people with colorectal cancer who had received surgery had lower survival rates than non-Aboriginal people, even though we found no overall differences in time to surgery, surgical rates, post-surgical complications, or receipt of adjuvant therapies or follow-up colonoscopies. However, small differences and delays along the cancer treatment pathway, possibly caused by cultural barriers to health care, may have resulted in lower survival for Aboriginal people with colorectal cancer. To ensure that survival rates improve, further work is needed to understand and reduce potential barriers to Aboriginal people with colorectal cancer receiving the best care.

Box 1 – Inclusion and exclusion criteria for the NSW Population-wide Study of colorectal cancer diagnosed during 2001–2007 in New South Wales

Box 2 – Comparison of socio-demographic and clinical data for 29 777 Aboriginal and non-Aboriginal people diagnosed with colorectal cancer during 2001–2007 in New South Wales

Aboriginal


Non-Aboriginal


P

Number

%

Number

%


Total number

278

29 499

Sex

0.864

Men

150

54%

16 068

54%

Women

128

46%

13 431

46%

Age at diagnosis, years

< 0.001

18–49

47

17%

1901

6%

50–59

49

18%

4256

14%

60–69

81

29%

7678

26%

70–79

77

28%

9216

31%

≥ 80

24

9%

6448

22%

Place of residence at diagnosis*

< 0.001

Major cities

114

41%

20 184

68%

Inner regional

103

37%

7177

24%

Rural

61

22%

2138

7%

Site of cancer

0.555

Colon

174

63%

19 342

66%

Rectum

81

29%

7785

26%

Rectosigmoid

23

8%

2372

8%

Spread of disease at diagnosis

0.551

Localised

98

35%

9985

34%

Regional

102

37%

11 801

40%

Distant

54

19%

4977

17%

Unknown

24

9%

2736

9%

Socio-economic disadvantage*

< 0.001

Least disadvantaged

15

5%

5296

18%

Second least disadvantaged

34

12%

6324

21%

Third least disadvantaged

43

15%

4762

16%

Second most disadvantaged

67

24%

6218

21%

Most disadvantaged

119

43%

6899

23%

Comorbid conditions

Diabetes

56

21%

4321

15%

0.009

Cardiovascular disease§

52

19%

4405

15%

0.071

Chronic pulmonary disease

33

12%

2360

8%

0.016

Renal disease

14

5%

1262

4%

0.518

Liver disease

8

3%

810

3%

0.879

Other comorbid conditions

17

6%

2511

9%

0.162

Surgical treatment by 12 months post-diagnosis

0.480

Emergency presentation

36

13%

3651

12%

Planned surgical treatment

176

63%

19 641

67%

No surgical treatment

66

24%

6207

21%


* Based on Local Government Area of residence at time of diagnosis. † “Rural” includes outer regional, remote and very remote. ‡ Comorbidities were not available for 453 people, of whom six were Aboriginal and 447 were non-Aboriginal. § Myocardial infarction, congestive heart failure, peripheral vascular disease, or cerebrovascular disease.

Box 3 – Cumulative mortality from colorectal cancer for 278 Aboriginal and 29 499 non-Aboriginal people diagnosed in New South Wales during 2001–2007

Box 4 – Mortality and hazard ratios for death from colorectal cancer for 278 Aboriginal people, compared with those for 29 499 non-Aboriginal people in New South Wales during 2001–2007


Hazard ratios for death from colorectal cancer (v non-Aboriginal people)

Aboriginal (unadjusted)

1.33 (95% CI, 1.09–1.61)

Aboriginal (adjusted)*

Surgical treatment

1.68 (95% CI, 1.32–2.09)

No surgical treatment

1.05 (95% CI, 0.70–1.50)

Unadjusted mortality 5 years after diagnosis

Aboriginal

43%

Non-Aboriginal

33%


* Adjusted for sex, age at diagnosis, year of diagnosis, place or residence, site of cancer, spread of disease at diagnosis, socio-economic disadvantage, and comorbid conditions.

Box 5 – Cumulative mortality from colorectal cancer for 278 Aboriginal and 29 499 non-Aboriginal people diagnosed in New South Wales during 2001–2007, by surgical treatment received

Box 6 – Cumulative incidence of colonoscopy after surgery for colorectal cancer for 212 Aboriginal and 23 292 non-Aboriginal people diagnosed in New South Wales during 2001–2007*


* Shaded areas represent the 95% confidence intervals.

Box 7 – Characteristics of 145 Aboriginal people in the Patterns of Care Study data diagnosed with colorectal cancer in New South Wales during 2001–2010

Number

%


Sex

Men

83

57%

Women

62

43%

Age at diagnosis, years

18–49

38

26%

50–59

27

19%

60–69

50

34%

70–79

25

17%

≥ 80

5

3%

Place of residence at diagnosis*

Major cities

44

30%

Inner regional

42

29%

Rural

59

41%

Site of cancer

Colon

88

61%

Rectum

35

24%

Rectosigmoid

22

15%

Spread of disease at diagnosis

Localised

51

35%

Regional

57

39%

Distant

34

23%

Unknown

3

2%

Socio-economic disadvantage*

Least disadvantaged

3

2%

Second least disadvantaged

14

10%

Third least disadvantaged

30

21%

Second most disadvantaged

42

29%

Most disadvantaged

56

39%

Comorbidities

Diabetes

26

18%

Cardiovascular disease

25

17%

Chronic pulmonary disease

28

19%

Liver disease

6

4%

Other comorbid conditions

7

5%

Tumour size at diagnosis, mm

0–29

24

17%

30–44

28

19%

45–59

30

21%

≥ 60

29

20%

Not available

34

23%


* Based on postcode of residence at time of diagnosis. † “Rural” includes outer regional, remote and very remote. ‡ Comorbidities not available for five people.

Received 15 October 2015, accepted 22 December 2015

  • Kristie Weir1
  • Rajah Supramaniam2
  • Alison Gibberd1
  • Anthony Dillon3
  • Bruce K Armstrong4,5
  • Dianne L O'Connell2,4

  • 1 University of Sydney, Sydney, NSW
  • 2 Cancer Council NSW, Sydney, NSW
  • 3 Institute for Positive Psychology and Education, Australian Catholic University, Sydney, NSW
  • 4 Sydney School of Public Health, University of Sydney, Sydney, NSW
  • 5 Sax Institute, Sydney, NSW

Correspondence: rajahs@nswcc.org.au

Acknowledgements: 

This study was conducted as part of the Aboriginal Patterns of Cancer Care Project (APOCC), which was funded by a National Health and Medical Research Council Health Services Research grant (application 440202). Linkage of the POC data to the population datasets was funded by a Cancer Institute NSW Epidemiology Linkage grant (application 10/EPI/2-05).

Competing interests:

No relevant disclosures.

  • 1. Morrell S, You H, Baker D. Estimates of cancer incidence, mortality and survival in aboriginal people from NSW, Australia. BMC Cancer 2012; 12: 168.
  • 2. Chong A, Roder D. Exploring differences in survival from cancer among Indigenous and non-Indigenous Australians: implications for health service delivery and research. Asian Pac J Cancer Prev 2010; 11: 953-961.
  • 3. Moore SP, Green AC, Bray F, et al. Colorectal cancer among Indigenous and non-Indigenous people in Queensland, Australia: toward survival equality. Asia Pac J Clin Oncol 2014; doi: 10.1111/ajco.12164 [Epub ahead of print].
  • 4. Condon JR, Cunningham J, Barnes T, et al. Cancer diagnosis and treatment in the Northern Territory: assessing health service performance for indigenous Australians. Intern Med J 2006; 36: 498-505.
  • 5. Clinical Oncological Society of Australia; Australian Cancer Network. Guidelines for the prevention, early detection and management of colorectal cancer. Canberra: National Health and Medical Research Council, 1999. https://www.nhmrc.gov.au/_files_nhmrc/publications/attachments/cp62.pdf (accessed Dec 2015).
  • 6. Australian Cancer Network Colorectal Cancer Guidelines Revision Committee. Clinical practice guidelines for the prevention, early detection and management of colorectal cancer. Sydney: The Cancer Council Australia and Australian Cancer Network; 2005. https://www.nhmrc.gov.au/_files_nhmrc/publications/attachments/cp106_0.pdf (accessed Dec 2015).
  • 7. Supramaniam R, Gibberd A, Dillon A, et al. Increasing rates of surgical treatment and preventing comorbidities may increase breast cancer survival for Aboriginal women. BMC Cancer 2014; 14: 163.
  • 8. Rodger JC, Supramaniam R, Gibberd AJ, et al. Prostate cancer mortality outcomes and patterns of primary treatment for Aboriginal men in New South Wales, Australia. BJU Int 2015; 115 Suppl 5: 16-23.
  • 9. Department of Health and Aged Care. Measuring remoteness: Accessibility/Remoteness Index of Australia (ARIA). Revised edition. (Occasional Papers: New Series, number 14). Canberra: Department of Health and Aged Care; 2001. https://www.health.gov.au/internet/main/publishing.nsf/Content/E2EE19FE831F26BFCA257BF0001F3DFA/$File/ocpanew14.pdf (accessed Dec 2015).
  • 10. Australian Bureau of Statistics. 2033.0.55.001 — Census of population and housing: Socio-Economic Indexes for Areas (SEIFA), Australia — data cube only, 2006 [internet]. http://www.abs.gov.au/AUSSTATS/abs@.nsf/allprimarymainfeatures/356A4186CCDDC4D1CA257B3B001AC22C?opendocument (accessed Dec 2015).
  • 11. Goldsbury DE, Armstrong K, Simonella L, et al. Using administrative health data to describe colorectal and lung cancer care in New South Wales, Australia: a validation study. BMC Health Serv Res 2012; 12: 387.
  • 12. Charlson ME, Pompei P, Ales KL, et al. A new method of classifying prognostic comorbidity in longitudinal studies: development and validation. J Chronic Dis 1987; 40: 373-383.
  • 13. Grambsch PM, Therneau TM. Proportional hazards tests and diagnostics based on weighted residuals. Biometrika 1994; 81: 515-526.
  • 14. Gray RJ. A Class of K-sample tests for comparing the cumulative incidence of a competing risk. Ann Stat 1988; 16: 1141-1154.
  • 15. Australian Bureau of Statistics. 2033.0.55.001 — Census of population and housing: Socio-Economic Indexes for Areas (SEIFA), Australia — data cube only, 2001 [internet]. http://www.abs.gov.au/AUSSTATS/abs@.nsf/allprimarymainfeatures/C53F24374E92E8D3CA2573F0000DA0BE?opendocument (accessed Dec 2015).
  • 16. Armstrong K, O’Connell D, Leong D, et al. The New South Wales colorectal cancer care survey 2000. Part 2 — chemotherapy management. Sydney: Cancer Council NSW, 2005. http://www.cancercouncil.com.au/wp-content/uploads/2010/09/CCC-Chemo-Report-Final-2007.pdf (accessed Dec 2015).
  • 17. Armstrong K, Kneebone A, O’Connell DL, et al. The New South Wales colorectal cancer care survey 2000. Part 3. Radiotherapy management for rectal cancer. Sydney: Cancer Council NSW, 2007. http://www.cancercouncil.com.au/wp-content/uploads/2010/09/NSW-CC-Radio-Report-Final-2007.pdf (accessed Dec 2015).
  • 18. Jorgensen ML, Young JM, Dobbins TA, et al. Does patient age still affect receipt of adjuvant therapy for colorectal cancer in New South Wales, Australia? J Geriatr Oncol 2014; 5: 323-330.
  • 19. Hill S, Sarfati D, Robson B, Blakely T. Indigenous inequalities in cancer: what role for health care? ANZ J Surg 2013; 83: 36-41.
  • 20. Christou A, Thompson SC. Colorectal cancer screening knowledge, attitudes and behavioural intention among Indigenous Western Australians. BMC Public Health 2012; 12: 528.
  • 21. Treloar C, Gray R, Brener L, et al. Health literacy in relation to cancer: Addressing the silence about and absence of cancer discussion among Aboriginal people, communities and health services. Health Soc Care Community 2013; 21: 655-664.
  • 22. Treloar C, Gray R, Brener L, et al. “I can’t do this, it’s too much”: building social inclusion in cancer diagnosis and treatment experiences of Aboriginal people, their carers and health workers. Int J Public Health 2014; 59: 373-379.
  • 23. Newman CE, Gray R, Brener L, et al. One size fits all? The discursive framing of cultural difference in health professional accounts of providing cancer care to Aboriginal people. Ethn Health 2013; 18: 433-447.

Author

remove_circle_outline Delete Author
add_circle_outline Add Author

Comment
Do you have any competing interests to declare? *

I/we agree to assign copyright to the Medical Journal of Australia and agree to the Conditions of publication *
I/we agree to the Terms of use of the Medical Journal of Australia *
Email me when people comment on this article

access_time 10:56, 23 April 2016
Kathryn Ives

To the Editor: In the March 2016 issue of the Medical Journal of Australia,[1] the authors presented a thoughtful comparison of the surgical and survival outcomes for Indigenous and non-Indigenous Australians with colorectal cancer in NSW.
The article supports the current national statistics observing that risk of death for patients with colorectal cancer is higher for Indigenous Australians,[2] and was able to specify that it was not until 18 months post surgery that the disparity in survival emerged.[1] No discernible differences in the treatment and follow-up for Indigenous and non-Indigenous Australians were identified.[1]
A limitation of the study was the sole use of quantitative data sources (registries, inpatient health records and death records) combined with a conclusion identifying the primary health barrier to the survival disparity as ‘cultural barriers’.[1] The authors oblique definition for ‘cultural barriers’ echoes a deficit based approach to Indigenous health, focusing on negative contributing factors often associated with Indigenous Australians; health illiteracy, feelings of shame, fatalism and embarrassment.[1] The language utilised by the authors seems to place blame on Indigenous peoples rather than simply address an institutional barrier. 
If the conclusions of the authors[1] are correct and more work is required to identify the actual health care barriers for Indigenous Australians with colorectal cancer, where do we look for this information?
While the digital collection and storage of health data on an ever-growing scale is currently being heralded as the answer for future innovations in oncology,[3] it is unlikely that ‘big data’, ultimately an extension of the data methodology utilised in the article by Weir,[1] will enable better health outcomes for Indigenous Australians.
Hopefully strength based projects like CanDAD (Cancer Data and Aboriginal Disparities Project)[4] will provide the relevant information required to discover what the actual health care barriers are and assist in the reformation of cancer care for Indigenous Australians.

References
1. Weir K, Supramaniam R, Gibberd A, et al. Comparing colorectal cancer treatment and survival for Aboriginal and non-Aboriginal people in New South Wales. Med J Aust. 2016;204(4):156. doi:10.5694/mja15.01153.
2. Australian Institute of Health and Welfare & Cancer Australia 2013. Cancer in Aboriginal and Torres Strait Islander peoples of Australia: an overview. Cancer series no. 78. Cat. no. CAN 75. Canberra: AIHW.
3. Murdoch T, Detsky A. The Inevitable Application of Big Data to Health Care. JAMA. 2013;309(13):1351-1352. doi:10.1001/jama.2013.393.
4. Brown A, Roder D, Yerrell P, et al. Cancer Data and Aboriginal Disparities Project (CanDAD) - an overdue cancer control initiative. Eur J Cancer Care. 2016;25(2):208-213. doi:10.1111/ecc.12466.

Competing Interests: No relevant disclosures

Ms Kathryn Ives
Barwon Health University Hospital Geelong

Responses are now closed for this article.