Treatment patterns for cancer in Western Australia: does being Indigenous make a difference?

There is little documented research examining disparities in cancer services between the Indigenous and non-Indigenous populations of Australia. Surgical procedures for cancer have received almost no attention, although differences have been seen between Indigenous patients and other patients in utilisation of hospital procedures, including those for all neoplasms combined.1,2 Inequalities in access to cardiovascular healthcare have also been reported.3 Furthermore, living in a rural area in Australia has been shown to affect cancer treatment patterns,4,5 and being treated in a rural hospital has been shown to worsen patient outcomes.4,5 The finding of a lower total procedure rate in the Indigenous population1,2 is consistent with these findings.

Our exploratory study aimed to examine possible disparities between the Indigenous and non-Indigenous populations of Western Australia (WA) in the uptake of cancer surgery for three common cancers (breast, prostate and lung), using administrative data collected routinely over 20 years.

The Indigenous population accounted for 2% of lung cancer cases. The Indigenous patients were younger and more likely to be female than the non-Indigenous patients (Box 1). Among the lung cancer patients who received surgical intervention, age and sex distribution were similar in the Indigenous and non-Indigenous groups. There was a tendency for Indigenous cases to not receive surgery, although this only reached significance with the longer time period (1982–2001) (Box 2).

Very few Indigenous men were recorded as having prostate cancer. The mean age of the Indigenous and non-Indigenous groups was similar. A much smaller proportion of Indigenous patients received radical or non-radical prostatectomy (Box 1). As only one Indigenous person received a radical prostatectomy, logistic regression was not performed. The likelihood of receiving non-radical prostatectomy was lower for Indigenous patients than for non-Indigenous patients in the demographically adjusted model but not in the fully adjusted model (Box 2).

Among women with breast cancer there was no difference between Indigenous and non-Indigenous groups in the proportion who received breast-conserving surgery (Box 1). Likewise, the ages of the groups were similar. Logistic regression showed that Indigenous women had similar treatment patterns to non-Indigenous women (Box 2).

Age-standardised cancer incidence rates have tended to be lower in the Indigenous population than in the non-Indigenous population.14 In part, this may be attributable to known difficulties in identifying all Indigenous people in the hospital, cancer and death registries,15 which would result in the true effect of being Indigenous being underestimated. Furthermore, poor life expectancy for Indigenous people may mask cancers that are latent at the time of early death. The small numbers of diagnosed and identified cases limit the potential of the statistical analysis to illuminate treatment patterns and outcomes in the Indigenous population.

There is some evidence that Indigenous people with cancer in Australia generally have higher case fatality rates.16 This may be due to a higher relative incidence of cancers with high fatality, particularly lung cancer,14,17 later diagnosis or suboptimal treatment patterns. We found no difference in breast cancer treatment patterns, whereas there were differences in lung and prostate cancer treatment patterns.

Sociocultural and economic factors may influence treatment patterns and outcomes, as has been found with breast cancer.18 An Indigenous person may not have the financial resources, even with assistance programs, to travel for surgery and adjuvant treatment or to pay for medications;18 this may be compounded by a low rate of private health insurance.1 Cultural and religious barriers may also exist, such as sex of the healthcare provider,17 religious denomination of the hospital or a preference for traditional healing practices.19 There may also be concerns about how the immediate and extended family will cope with the illness and treatment,18 especially in areas lacking culturally sensitive aftercare services.19 Importantly, there may be concerns that treatment is ineffective and not worthwhile, especially for cancers with high case-fatality rates, such as lung cancer.

From a healthcare system perspective, plausible barriers exist at all stages of care.19 There are few Indigenous cancer specialists, and non-Indigenous specialists may have difficulty communicating effectively with patients and their families,1,20 potentially leading to paternalistic care3 and reduced compliance with treatment.2,20 Coordinated care between cancer centres, local hospitals and primary care services is essential, but service gaps are commonly reported.19 From a clinical perspective, the low rates of surgical intervention for lung cancer in this study may indicate that the cancers are more advanced and less amenable to treatment in the Indigenous population,21 or, alternatively, there may be comorbidity17 or other valid reasons why patients or surgeons have decided that surgical treatment is not the preferred option.20,22 Nevertheless, the potential for systematic unintentional treatment disparities remains.20,22

A number of policy options are available, but the primary concern must be to reduce social and health inequities for the Indigenous population.3,19 The results of this study suggest four possible policies. Firstly, research in the field to determine the reasons for treatment choice and to ensure that barriers to early treatment are minimised.17,20,22 A second policy step is to engage the Indigenous communities, and together find appropriate strategies.3 Thirdly, administrative datasets have proved useful in profiling morbidity and mortality patterns in the non-Indigenous population, but their use will remain limited in the Indigenous population unless sufficient cases are available for analysis. This could be achieved by better identification of the Indigenous population in the datasets and interstate cooperation to merge de-identified data. Finally, Indigenous issues must be embedded in cancer control strategy plans, and they must be implemented.

2 Odds ratio of receiving cancer surgery for Indigenous people versus non-Indigenous people in Western Australia

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* Odds ratios for 1982–2001 and 1991–2001 (first analysis) were adjusted demographically for patient age, Box–Tidwell transformation of age, calendar period, Charlson index and marital status. The lung cancer analyses were also adjusted for sex and histological type. † For the breast cancer analyses, the periods examined were 1982–2000 and 1991–2000, respectively, rather than 1982–2001 and 1991–2001.

‡ Odds ratios for 1991–2001 (second analysis) were adjusted demographically as above and also for disadvantage using patient Index of Relative Socioeconomic Disadvantage (IRSD),10 Accessibility Remoteness Index of Australia (ARIA),11 hospital status (public or private) and location (metropolitan or rural), and patient insurance status (public or private).