Background
In Canada, previous studies show an increase in cancer incidence in FN people compared to non-FN people, however this observed trend seems to be cancer site specific [
5‐
10]. Cancer stage at diagnosis is an important prognostic indicator, and evidence suggests FN people are more likely to be diagnosed at later stages than non-FN Canadians [
11‐
13]. Disparities in survival are equally concerning. Cancer mortality is higher among FN in Ontario than non-FN people [
7], and while trends indicate the mortality for breast and colorectal cancers are decreasing among non-FN, they are increasing among FN people. Colorectal cancer mortality in particular increased 8-fold among FN people in Manitoba between 1984 and 2008 [
11]. FN people experience significantly poorer cancer survival than non-FN in multiple Canadian provinces [
5‐
7,
12,
14‐
16], independent of stage at diagnosis [
14], income, or rural residency [
16].
Similar disparities in cancer incidence and outcomes between Indigenous peoples and their non-Indigenous counterparts are reported elsewhere. In the United States, cancer mortality rates have progressively declined among non-Indigenous Americans, yet remain unchanged among Indigenous peoples [
17‐
19]. Indigenous peoples in Australia are more likely to have advanced disease at diagnosis and less likely to receive certain cancer treatments [
8,
20‐
22]. Similarly, Indigenous peoples in New Zealand (Maori) experience significantly higher incidence of cancer than non-Indigenous New Zealanders, with evidence of disparities in stage at diagnosis, treatments received, and survival [
8,
23‐
25].
Emerging evidence demonstrates the shifting trends that are causing the widening disparity between FN people and the general population, yet epidemiological studies focused on cancer incidence and stage at diagnosis at the population level are sparse, particularly within the Canadian context. Within Manitoba, breast, colorectal and cervical cancers have been studied in the FN population, however, to date, no study has investigated general cancer trends. In this article, findings from a secondary analysis of provincial health administrative data are reported and address three objectives: a) to describe the demographics, comorbidities, site and stage of cancer at diagnosis among FN people and All Other Manitobans (AOM) who received a cancer diagnosis between April 1, 2004 and March 31, 2011; b) to compare annual crude and adjusted incidence rates for each cohort; c) to investigate mortality outcomes for each cohort. Supporting this research to address identified research gaps is an interdisciplinary team of researchers and FN community members.
Discussion
This study aimed to describe the characteristics of FN patients and AOM diagnosed with cancer between 2004 and 2011, and examine cancer incidence, site, stage at diagnosis, and mortality. Our results indicate that the FN cohort was significantly younger, and had a significantly higher Charlson Comorbidity Index compared to the AOM cohort. Although crude incidence rates among the FN cohort were half that of AOM, these differences were not sustained after adjusting for age, sex, income and area of residence. We found no significant trends in cancer incidence in either cohort over time. We did, however, find significant differences in cancer sites diagnosed between cohorts. Notably, our results show a higher proportion of FN patients diagnosed with cancer at stages III and IV than AOM, and a higher risk of all-cause mortality and cancer-specific mortality in the FN cohort.
We found that the proportion of prostate, bladder, and uterine cancers were significantly lower in the FN cohort, while the proportion of cervical, colorectal and kidney cancers were significantly higher in the FN cohort compared to AOM. Elsewhere in Canada, incidence of bladder, breast and uterine cancers and melanoma were lower among FN people in Ontario [
7], and lower incidence of breast and prostate cancers were found among FN people in British Columbia [
6]. A significantly higher incidence of colorectal and cervical cancers have been found among FN people in British Columbia and Manitoba [
6,
9,
11], and a significantly higher incidence of colorectal, kidney and cervical cancers among FN people in Ontario [
5,
7]. Differences in cancer incidence may be related to genetic risk or environmental exposures, however, we wish to draw attention to alternative factors that may explain, in part, some of these differences. Higher proportions of cervical cancer among FN women may suggest poor access to screening services, which identify pre-cancerous changes that can be treated to prevent cancer. A recent meta-analysis found increased risk of invasive cervical cancer and cervical cancer-related mortality among Indigenous women compared to non-Indigenous women, yet no increased risk of cervical dysplasia or carcinoma in situ (precursors to cervical cancer) [
30]. These results suggest “structural, social, or individual barriers to screening, rather than baseline risk factors, are influencing poor health outcomes” [30, p148].
Poor access to cervical cancer screening may be related to geographical availability of services as well as access to culturally safe services, which are particularly important within the context of historical trauma and experiences of residential school survivors, and the invasive nature of cervical cancer screening [
31‐
34]. Within Canada, research indicates Indigenous women face multiple structural barriers to accessing cervical cancer screening (including historical, political, socioeconomic, and health systems factors), many of are rooted in colonial history [
32,
33]. Within Manitoba, FN women over 40 are less likely to receive a pap test than AOM, FN women younger than 25 are more likely to receive a pap test, and there is no difference between FN and AOM in pap testing for women 25–39 [
9]. Higher incidence of cervical cancer among FN women may also indicate poor access to follow-up care after an abnormal Pap test result [
6,
33].
In our study, a higher proportion of FN people compared with AOM were diagnosed with cancer at stages III (18.7% vs. 15.4%) and IV (22.4% vs. 19.9%). Several other Canadian studies have demonstrated similar patterns of late-stage diagnosis, with FN women more likely to be diagnosed with breast cancer at later stages than non-FN women [
11‐
13]. This is particularly concerning given that cancer stage at diagnosis has a significant impact on treatment options and cancer outcomes, and is an important indicator of the quality of, and access to screening and early detection services [
35,
36]. FN people in Canada experience difficulty accessing primary care [
37,
38] and diagnostic services [
39,
40], which may be contributing to higher rates of stage III and IV diagnoses. Many FN communities are located in rural or remote areas characterized by low population density, poor transportation infrastructure, limited resources for diagnostics and high turnover of healthcare professionals. This results in limited or non-existent access to local healthcare services, poor continuity of care, and compromised quality of care [
34,
40‐
44]. As such, many FN patients must travel to access basic diagnostic services, treatment and supportive care. Lengthy travel time, coupled with transportation that is not feasible, convenient or affordable creates significant barriers to accessing cancer care [
45‐
47]. Although there are resources to support medical travel, particularly for status FN people, accessing these resources can come with challenges [
39,
42].
Accessing health care, however, requires more than service or healthcare provider availability – patients must also feel that their concerns are heard, and that care will be provided that is free of judgment and culturally safe [
48]. Cultural safety is an approach to delivering care that is based on establishing trusting and reciprocal relationships between a patient and their healthcare provider [
49]. Lack of culturally safe care has been noted to be a barrier to accessing cancer care among FN people [
34,
45,
50,
51]. Racism, discrimination, and fear of judgment have been noted to impede access to both primary care [
37,
38] and cancer care [
32,
47,
50,
52,
53], by causing patients to delay or avoid accessing care. These experiences are further exacerbated by histories of historical trauma, residential school attendance and Indian hospitals, which have been noted to increase distrust of healthcare providers. Feelings of distrust, negative experiences within institutional settings, culturally incongruous systems and experiences with marginalization and racism can result in patients delaying or avoiding seeking care [
42,
46,
47,
53]. It is unclear to what extent healthcare providers are aware of the impact of their actions on FN peoples access to healthcare, and more research is needed to understand this relationship.
Finally, our results show that FN people had a higher risk of all-cause mortality and cancer-specific mortality than AOM both before and after adjustment for age, sex, cancer stage at diagnosis, income, region of residence and comorbidities. Our results also show that FN patients had a higher risk of death from
any cause (HR 1.234, 95% CI 1.15–1.32,
p < 0.0001) and a higher risk of
cancer-related death (HR 1.099, 95% CI 1.001–1.207) at 5 years post-cancer diagnosis than AOM. These results are similar to other studies in Canada, indicating higher cancer-related mortality among FN people [
6,
7,
14‐
16].
While disparities in cancer-related survival are multifactorial, the main determinant of survival is cancer stage at diagnosis [
29]. Underlying these disparities, however, are a host of health inequities experienced by FN people in Canada, some of which are discussed above. Health inequities are the systematic and unjust differences in health between socioeconomic groups; these differences are generated by social, economic and environmental factors and contexts amenable to change, and are not a result of ‘lifestyle’ or personal choices [
54]. Within Canada, a significant body of evidence demonstrates the substantial health inequities experienced by Indigenous peoples (including FN people) [
55,
56]. Researchers, healthcare providers and policy makers must consider the context of these inequities, and how they are, at least in part, “the direct and indirect present-day symptoms of a history of loss of lands and autonomy and the results of the political, cultural, economic and social disenfranchisement that ensued” ([
57], p59). Although individual characteristics, comorbidities, tumor biology, cancer treatment impact, and access to/use of healthcare services impact survival [
6,
15,
58], an agenda to improve cancer outcomes among Indigenous peoples, including FN people, must also acknowledge and address health and social inequities. In particular, the tendency to focus on ‘lifestyle’ or behavioral risk factors (i.e., smoking, diet, alcohol) and education about risk factors, while ignoring the “drivers of these behaviors” must be disrupted ([
59], pS517]). Our intent here is to draw attention to the ‘causes of the causes’ and determinants of Indigenous health, rather than perpetuate the discourse that focuses solely on genetic and ‘lifestyle’ risk factors as potential causes of the disparities and inequities described.
Limitations
There are several limitations to this study. First, only those individuals registered under the Indian Act were included in the FN cohort, with non-registered FN people subsequently included with AOM. This may have resulted in an underrepresentation of the differences in stage at cancer diagnosis and outcomes given that non-registered FN people experience many of the same socioeconomic conditions, access to healthcare issues, and colonial history as registered FN people. At present, there is no mechanism to identify non-registered FN people in these datasets. Second, we were not able to analyze differences in mortality between the FN and AOM cohorts by disease site, and there may be significant differences in mortality and survival depending on cancer site. Further investigation is needed.
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