Stage at diagnosis and comorbidity influence breast cancer survival in First Nations women in Ontario, Canada

Assessing Breast Cancer Screening and Outcomes Among First Nations Women in Alberta

BACKGROUND

Breast cancer (BC) incidence rates for First Nations (FN) women in Canada have been steadily increasing and are often diagnosed at a later stage. Despite efforts to expand the reach of BC screening programs for FN populations in Alberta (AB), gaps in screening and outcomes exist.

METHODS

Existing population-based administrative databases including the AB BC Screening Program, the AB Cancer Registry, and an AB-specific FN registry data were linked to evaluate BC screening participation, detection, and timeliness of outcomes in this retrospective study. Tests of proportions and trends compared the findings between FN and non-FN women, aged 50-74 years, beginning in 2008. Incorporation of FN principles of ownership, control, access, and possession (OCAP®) managed respectful sharing and utilization of FN data and findings.

RESULTS

The average age-standardized participation (2013-8) and retention rates (2015-6) for FN women compared to non-FN women in AB were 23.8% (P < .0001) and 10.3% (P = .059) lower per year, respectively. FN women were diagnosed with an invasive cancer more often in Stage II (P-value = .02). Following 90% completion of diagnostic assessments, it took 2-4 weeks longer for FN women to receive their first diagnosis as well as definitive diagnoses than non-FN women.

CONCLUSION

Collectively, these findings suggest that access to and provision of screening services for FN women may not be equitable and may contribute to higher BC incidence and mortality rates. Collaborations between FN groups and screening programs are needed to eliminate these inequities to prevent more cancers in FN women.

The effect of general practice contact on cancer stage at diagnosis in Aboriginal and non-Aboriginal residents of New South Wales

PURPOSE

Older age, risks from pre-existing health conditions and socio-economic disadvantage are negatively related to the prospects of an early-stage cancer diagnosis. With older Aboriginal Australians having an elevated prevalence of these underlying factors, this study examines the potential for the mitigating effects of more frequent contact with general practitioners (GPs) in ensuring local-stage at diagnosis.

METHODS

We compared the odds of local vs. more advanced stage at diagnosis of solid tumours according to GP contact, using linked registry and administrative data. Results were compared between Aboriginal (n = 4,084) and non-Aboriginal (n = 249,037) people aged 50 + years in New South Wales with a first diagnosis of cancer in 2003-2016.

RESULTS

Younger age, male sex, having less area-based socio-economic disadvantage, and fewer comorbid conditions in the 12 months before diagnosis (0-2 vs. 3 +), were associated with local-stage in fully-adjusted structural models. The odds of local-stage with more frequent GP contact (14 + contacts per annum) also differed by Aboriginal status, with a higher adjusted odds ratio (aOR) of local-stage for frequent GP contact among Aboriginal people (aOR = 1.29; 95% CI 1.11-1.49) but not among non-Aboriginal people (aOR = 0.97; 95% CI 0.95-0.99).

CONCLUSION

Older Aboriginal Australians diagnosed with cancer experience more comorbid conditions and more socioeconomic disadvantage than other Australians, which are negatively related to diagnosis at a local-cancer stage. More frequent GP contact may act to partly offset this among the Aboriginal population of NSW.

The fraction of life years lost after diagnosis (FLYLAD): a person-centred measure of cancer burden

BACKGROUND

Cancer control initiatives are informed by quantifying the capacity to reduce cancer burden through effective interventions. Burden measures using health administrative data are a sustainable way to support monitoring and evaluating of outcomes among patients and populations. The Fraction of Life Years Lost After Diagnosis (FLYLAD) is one such burden measure. We use data on Aboriginal and non-Aboriginal South Australians from 1990 to 2010 to show how FLYLAD quantifies disparities in cancer burden: between populations; between sub-population cohorts where stage at diagnosis is available; and when follow-up is constrained to 24-months after diagnosis.

METHOD

FLYLADcancer is the fraction of years of life expectancy lost due to cancer (YLLcancer) to life expectancy years at risk at time of cancer diagnosis (LYAR) for each person. The Global Burden of Disease standard life table provides referent life expectancies. FLYLADcancer was estimated for the population of cancer cases diagnosed in South Australia from 1990 to 2010. Cancer stage at diagnosis was also available for cancers diagnosed in Aboriginal people and a cohort of non-Aboriginal people matched by sex, year of birth, primary cancer site and year of diagnosis.

RESULTS

Cancers diagnoses (N = 144,891) included 777 among Aboriginal people. Cancer burden described by FLYLADcancer was higher among Aboriginal than non-Aboriginal (0.55, 95% CIs 0.52-0.59 versus 0.39, 95% CIs 0.39-0.40). Diagnoses at younger ages among Aboriginal people, 7 year higher LYAR (31.0, 95% CIs 30.0-32.0 versus 24.1, 95% CIs 24.1-24.2) and higher premature cancer mortality (YLLcancer = 16.3, 95% CIs 15.1-17.5 versus YLLcancer = 8.2, 95% CIs 8.2-8.3) influenced this. Disparities in cancer burden between the matched Aboriginal and non-Aboriginal cohorts manifested 24-months after diagnosis with FLYLADcancer 0.44, 95% CIs 0.40-0.47 and 0.28, 95% CIs 0.25-0.31 respectively.

CONCLUSION

FLYLAD described disproportionately higher cancer burden among Aboriginal people in comparisons involving: all people diagnosed with cancer; the matched cohorts; and, within groups diagnosed with same staged disease. The extent of disparities were evident 24-months after diagnosis. This is evidence of Aboriginal peoples' substantial capacity to benefit from cancer control initiatives, particularly those leading to earlier detection and treatment of cancers. FLYLAD's use of readily available, person-level administrative records can help evaluate health care initiatives addressing this need.

Radiation Therapy and Indigenous Peoples in Canada and Australia: Building Paths Toward Reconciliation in Cancer Care Delivery

Indigenous peoples represent approximately 5% of the world's population and reside in over 90 countries worldwide. They embody a rich diversity of cultures, traditions, languages and relationships with the land that are shared through many generations and that are distinct from those of the settler societies within which they now live. Many Indigenous peoples have a shared experience of discrimination, trauma, and violation of rights, rooted in complex sociopolitical relationships with settler societies that are still ongoing. This results in continuing social injustices and pronounced disparities in health for many Indigenous peoples around the globe. Indigenous peoples exhibit a significantly higher cancer incidence, mortality, and poorer survival compared to non-Indigenous peoples. Cancer services, including radiotherapy, have not been designed to support the specific values and needs of Indigenous populations, resulting in poorer access to cancer services for Indigenous peoples globally across the entire cancer care spectrum. Specific to radiotherapy, available evidence demonstrates disparities in radiotherapy uptake between Indigenous and non-Indigenous patients. Radiotherapy centres are also located disparately further away from Indigenous communities. Studies are limited by a lack of Indigenous-specific data to help inform effective radiotherapy delivery. Recent Indigenous-led partnerships and initiatives have helped to address existing gaps in cancer care, and radiation oncologists play an important role in supporting such efforts. In this article, we present an overview of access to radiotherapy for Indigenous peoples in Canada and Australia, with a focus on strengthening cancer care delivery through education, partnerships, and research.

Breast cancer in Indigenous women living in Canada: a scoping review protocol

OBJECTIVE

The objective of this review is to describe and synthesize the current state of knowledge pertaining to breast cancer in Indigenous women living in Canada. We will examine the continuum of breast cancer care in this population, including breast cancer screening, diagnosis, treatment, and surveillance.

INTRODUCTION

Breast cancer in Indigenous women is an evolving health care concern in Canada, with mounting evidence suggesting that these women present at later stages, and have poorer survival rates compared with the general population. A comprehensive overview of the state of knowledge of breast cancer in this population is required.

INCLUSION CRITERIA

The population of interest will include Indigenous women living in Canada aged 18 years or older who have been screened or require screening for breast cancer, or who have been diagnosed with breast cancer. "Indigenous" will include women who identify as First Nations, Métis, or Inuit. Eligible sources must report on breast cancer risk factors, tumor characteristics, health systems access, screening, diagnosis, treatment, surveillance, or breast cancer outcomes. We will include analytic studies, surveys, case series, reviews, meta-analyses, and gray literature.

METHODS

We will conduct a search of five health sciences databases for relevant studies published in English or French from database inception onward. We will utilize dual independent screening for titles, abstracts, and full-text articles, and will utilize a similar method for gray literature sources. Data will be synthesized using a narrative approach, and outcomes of interest will be compared with data from the general breast cancer population.

REGISTRATION

Open Science Framework https://osf.io/xkde5.

Understanding culturally safe cancer survivorship care with inuit in an urban community

Cancer is a leading cause of death among Inuit. A legacy of colonialism, residential schools, and systemic racism has eroded trust among Inuit and many do not receive culturally safe care. This study aimed to explore the meaning of culturally safe cancer survivorship care for Inuit, and barriers and facilitators to receiving it in an urban setting in Ontario Canada. As Inuit and Western researchers, we conducted a descriptive qualitative study. We held two focus groups (n = 27) with cancer survivors and family members, and semi-structured interviews (n = 7) with health providers. Data were analysed using thematic content analysis.Three broad themes emerged as central to culturally safe care: access to traditional ways of life, communication, and family involvement. Family support, patient navigators, and designated spaces were facilitators; lack of support for traditional ways, like country food, was a barrier. Participants were clear what constituted culturally safe care, but major barriers exist. Lack of direction at institutional and governmental levels contributes to the complexity of issues that prevent Inuit from engaging in and receiving culturally safe cancer care. To understand how to transform healthcare to be culturally safe, studies underpinned by Inuit epistemology, values, and principles are required.

The multimorbidity profile of South African women newly diagnosed with breast cancer

Multimorbidity in women with breast cancer may delay presentation, affect treatment decisions and outcomes. We described the multimorbidity profile of women with breast cancer, its determinants, associations with stage at diagnosis and treatments received. We collected self-reported data on five chronic conditions (hypertension, diabetes, cerebrovascular diseases, asthma/chronic obstructive pulmonary disease, tuberculosis), determined obesity using body mass index (BMI) and tested HIV status, in women newly diagnosed with breast cancer between January 2016 and April 2018 in five public hospitals in South Africa. We identified determinants of ≥2 of the seven above-mentioned conditions (defined as multimorbidity), multimorbidity itself with stage at diagnosis (advanced [III-IV] vs. early [0-II]) and multimorbidity with treatment modalities received. Among 2,281 women, 1,001 (44%) presented with multimorbidity. Obesity (52.8%), hypertension (41.3%), HIV (22.0%) and diabetes (13.7%) were the chronic conditions that occurred most frequently. Multimorbidity was more common with older age (OR = 1.02; 95% CI 1.01-1.03) and higher household socioeconomic status (HSES) (OR = 1.06; 95% CI 1.00-1.13). Multimorbidity was not associated with advanced-stage breast cancer at diagnosis, but for self-reported hypertension there was less likelihood of being diagnosed with advanced-stage disease in the adjusted model (OR 0.80; 95% CI 0.64-0.98). Multimorbidity was associated with first treatment received in those with early-stage disease, p = 0.003. The prevalence of multimorbidity is high among patients with breast cancer. Our findings suggest that multimorbidity had a significant impact on treatment received in those with early-stage disease. There is need to understand the impact of multimorbidity on breast cancer outcomes.

Influence of Preexisting Diabetes on Survival After a Breast Cancer Diagnosis in First Nations Women in Ontario, Canada

PURPOSE

Survival after a breast cancer diagnosis is poorer in First Nations women with a preexisting comorbidity compared with comorbidity-free First Nations women in Ontario, Canada. Given the high prevalence of diabetes in this population, it is important to determine whether preexisting diabetes is related to poorer survival after a breast cancer diagnosis.

METHODS

All First Nations women were identified from a cohort of First Nations people diagnosed with breast cancer in diagnostic periods-1995 to 1999 and 2000 to 2004-and seen at a regional cancer program (RCP) in Ontario. Preexisting diabetes status and other factors, such as age at diagnosis, body mass index, and stage at diagnosis, were collected from medical charts at the regional cancer programs. The association between preexisting diabetes and First Nations status was examined by each of the demographic, personal, tumor, and treatment factors using logistic regression models. Survival was compared between First Nations women with (n = 67) and without (n = 215) preexisting diabetes, adjusted by significant study factors using a Cox proportional hazards regression model.

RESULTS

The 5-year survival rate among First Nations women with diabetes was 59.8% versus 78.7% among those without diabetes (P < .01). Preexisting diabetes significantly increased the risk of death among First Nations women with breast cancer (hazard ratio, 1.87; 95% CI, 1.12 to 3.13) after adjustment for age group, period of diagnosis, body mass index, other comorbidities at diagnosis, and stage.

CONCLUSION

This study recommends awareness of this survival discrepancy among the treatment team for First Nations patients with breast cancer with preexisting diabetes.

In search of Pan-American indigenous health and harmony

The objective of this article is to describe the state of North, Central, South American and Caribbean (Pan-American) indigenous health. The second objective is to identify recommendations for optimal healthcare and research strategies to achieve indigenous health equity. Current health disparities continue to present between indigenous populations and general populations. Research foci of Pan-American indigenous health center on health outcomes for chronic and acute disease as well as presence of indigenous in data sets. Research is both qualitative and quantitative. Recommendations to improve indigenous health in effort of health equity are variable yet feasible. Stronger epidemiology, continued cohesive Pan-American global strategies, better research alignment with emphasis to quality and comprehensive metric analyses in healthcare delivery are all avenues to improve the health of the indigenous. Research and healthcare delivery on the Pan-American indigenous must be maximized for optimal results, must be representative of the indigenous communities, must be implemented in best practice and must introduce sustainable healthcare delivery for Pan-American indigenous health equity.

Validity of Administrative Databases in Comparison to Medical Charts for Breast Cancer Treatment Data

Objective

Medical chart abstraction is the gold standard for collecting breast cancer treatment data for monitoring and research. A less costly alternative is the use of administrative databases. This study will evaluate administrative data in comparison to medical charts for breast cancer treatment information.

Study Design and Setting

A retrospective cohort design identified 2,401 women in the Ontario Breast Screening Program diagnosed with invasive breast cancer from 2006 to 2009. Treatment data were obtained from the Activity Level Reporting and Canadian Institute of Health Information databases. Medical charts were abstracted at cancer centres. Sensitivity, specificity, positive and negative predictive value, and kappa were calculated for receipt and type of treatment, and agreement was assessed for dates. Logistic regression evaluated factors influencing agreement.

Results

Sensitivity and specificity for receipt of radiotherapy (92.0%, 99.3%), chemotherapy (77.7%, 99.2%), and surgery (95.8%, 100%) were high but decreased slightly for specific radiotherapy anatomic locations, chemotherapy protocols, and surgeries. Agreement increased by radiotherapy year (trend test, p < 0.0001). Stage II/III compared to stage I cancer decreased odds of agreement for chemotherapy (OR = 0.66, 95% CI: 0.48–0.91) and increased agreement for partial mastectomy (OR = 3.36, 95% CI: 2.27–4.99). Exact agreement in treatment dates varied from 83.0% to 96.5%.

Conclusion

Administrative data can be accurately utilized for future breast cancer treatment studies.

Risk of cancer death by comorbidity severity and use of adjuvant chemotherapy among women with locoregional breast cancer

OBJECTIVES

To examine the associations of comorbidity and chemotherapy with breast cancer- and non-breast cancer-related death.

MATERIALS AND METHODS

Included were women with invasive locoregional breast cancer diagnosed in 2004 from seven population-based cancer registries. Data were abstracted from medical records and verified with treating physicians when there were inconsistencies and missing information on cancer treatment. Comorbidity severity was quantified using the Adult Comorbidity Evaluation 27. Treatment guideline concordance was determined by comparing treatment received with the National Comprehensive Cancer Network guidelines. Kaplan-Meier method and multivariable Cox proportional hazards regressions were employed for statistical analyses.

RESULTS

Of 5852 patients, 76% were under 70years old and 69% received guideline concordant adjuvant chemotherapy. Comorbidity was more prevalent in women age 70 and older (79% vs. 51%; p<0.001). After adjusting for tumor characteristics and treatment, severe comorbidity burden was associated with significantly higher cancer-related mortality in older patients (Hazard Ratio [HR]=2.38, 95% CI 1.08-5.24), but not in younger patients (HR=1.78, 95% CI 0.87-3.64). Among patients receiving guideline adjuvant chemotherapy, cancer-related mortality was significantly higher in older patients (HR=2.35, 95% CI 1.52-3.62), and those with severe comorbidity (HR=3.79, 95% CI 1.72-8.33).

CONCLUSIONS

Findings suggest that, compared to women with no comorbidity, patients with breast cancer age 70 and older with severe comorbidity are at increased risk of dying from breast cancer, even after adjustment for adjuvant chemotherapy and other tumor and treatment differences. This information adds to risk-benefit discussions and emphasizes the need for further study of the role for adjuvant chemotherapy in these patient groups.

Cancer risk factors and screening in First Nations in Ontario

INTRODUCTION

A lack of identifiers in health administrative databases limits our understanding of the cancer burden in First Nations. This study compares cancer risk factors and screening between First Nations in Ontario (on and off reserve) and non-Aboriginal Ontarians using two unique health surveys.

METHODS

We measured age-standardized prevalence estimates using the First Nations Regional Health Survey (RHS) Phase 2, 2008/10 (for First Nations on reserve) and the Canadian Community Health Survey (CCHS), 2007-2013 (for First Nations off reserve and non-Aboriginal Ontarians). We used prevalence rate ratios (RR) and Pearson's chisquare tests for differences in proportions to compare estimates between First Nations (on and off reserve) and non-Aboriginal Ontarians.

RESULTS

A higher proportion of First Nation men, women and adolescents on reserve smoked (RR = 1.97, 2.78 and 7.21 respectively) and were obese (RR = 1.73, 2.33 and 3.29 respectively) compared to their non-Aboriginal counterparts. Similar patterns were observed for First Nations off reserve. Frequent binge drinking was also more prevalent among First Nation men and women living on reserve (RR = 1.28 and 2.22, respectively) and off reserve (RR = 1.70 and 1.45, respectively) than non-Aboriginal Ontarians. First Nation men and women on reserve were about half as likely to consume fruit at least twice per day and vegetables at least twice per day compared to non-Aboriginal men and women (RR = 0.53 and 0.54, respectively). Pap test uptake was similar across all groups, while First Nation women on reserve were less likely to have had a mammogram in the last five years than non-Aboriginal women (RR = 0.85).

CONCLUSION

First Nations, especially those living on reserve, have an increased risk for cancer and other chronic diseases compared to non-Aboriginal Ontarians. These results provide evidence to support policies and programs to reduce the future burden of cancer and other chronic diseases in First Nations in Ontario.

Comorbidities contribute to the risk of cancer death among Aboriginal and non-Aboriginal South Australians: Analysis of a matched cohort study

BACKGROUND

Aboriginal Australians have poorer cancer survival than other Australians. Diagnoses at later stages and correlates of remote area living influence, but do not fully explain, these disparities. Little is known of the prevalence and influence of comorbid conditions experienced by Aboriginal people, including their effect on cancer survival. This study quantifies hospital recorded comorbidities using the Elixhauser Comorbidity Index (ECI), examines their influence on risk of cancer death, then considers effect variation by Aboriginality.

METHODS

Cancers diagnosed among Aboriginal South Australians in 1990-2010 (N = 777) were matched with randomly selected non-Aboriginal cases by birth year, diagnostic year, sex, and primary site, then linked to administrative hospital records to the time of diagnosis. Competing risk regression summarised associations of Aboriginal status, stage, geographic attributes and comorbidities with risk of cancer death.

RESULTS

A threshold of four or more ECI conditions was associated with increased risk of cancer death (sub-hazard ratio SHR 1.66, 95%CI 1.11-2.46). Alternatively, the presence of any one of a subset of ECI conditions was associated with similarly increased risk (SHR = 1.62, 95%CI 1.23-2.14). The observed effects did not differ between Aboriginal and matched non-Aboriginal cases. However, Aboriginal cases experienced three times higher exposure than non-Aboriginal to four or more ECI conditions (14.2% versus 4.5%) and greater exposure to the subset of ECI conditions (20.7% versus 8.0%).

CONCLUSION

Comorbidities at diagnosis increased the risk of cancer death in addition to risks associated with Aboriginality, remoteness of residence and disease stage at diagnosis. The Aboriginal cohort experienced comparatively greater exposure to comorbidities which adds to disparities in cancer outcomes.

Variations in outcomes for Indigenous women with breast cancer in Australia: A systematic review

This systematic review examines variations in outcomes along the breast cancer continuum for Australian women by Indigenous status. Multiple databases were systematically searched for peer-reviewed articles published from 1 January 1990 to 1 March 2015 focussing on adult female breast cancer patients in Australia and assessing survival, patient and tumour characteristics, diagnosis and treatment by Indigenous status. Sixteen quantitative studies were included with 12 rated high, 3 moderate and 1 as low quality. No eligible studies on referral, treatment choices, completion or follow-up were retrieved. Indigenous women had poorer survival most likely reflecting geographical isolation, advanced disease, patterns of care, comorbidities and disadvantage. They were also more likely to be diagnosed when younger, have advanced disease or comorbidities, reside in disadvantaged or remote areas, and less likely to undergo mammographic screening or surgery. Despite wide heterogeneity across studies, an overall pattern of poorer survival for Indigenous women and variations along the breast cancer continuum of care was evident. The predominance of state-specific studies and small numbers of included Indigenous women made forming a national perspective difficult. The review highlighted the need to improve Indigenous identification in cancer registries and administrative databases and identified key gaps notably the lack of qualitative studies in current literature.

The impact of comorbidity on cancer and its treatment

Answer questions and earn CME/CNE Comorbidity is common among cancer patients and, with an aging population, is becoming more so. Comorbidity potentially affects the development, stage at diagnosis, treatment, and outcomes of people with cancer. Despite the intimate relationship between comorbidity and cancer, there is limited consensus on how to record, interpret, or manage comorbidity in the context of cancer, with the result that patients who have comorbidity are less likely to receive treatment with curative intent. Evidence in this area is lacking because of the frequent exclusion of patients with comorbidity from randomized controlled trials. There is evidence that some patients with comorbidity have potentially curative treatment unnecessarily modified, compromising optimal care. Patients with comorbidity have poorer survival, poorer quality of life, and higher health care costs. Strategies to address these issues include improving the evidence base for patients with comorbidity, further development of clinical tools to assist decision making, improved integration and coordination of care, and skill development for clinicians. CA Cancer J Clin 2016;66:337-350. © 2016 American Cancer Society.

A critical review of methods for assessing cancer survival disparities in indigenous population

PURPOSE

An increasing cancer burden among indigenous populations has led to a growing literature about survival disparities between indigenous and nonindigenous persons. We aim to describe and appraise methods used to measure cancer survival in indigenous persons in the United States, Canada, Australia, and New Zealand.

METHODS

We searched Medline, Web of Science, and EMBASE for articles published between 1990 and 2015 that estimated survival in populations indigenous to one of these four countries. We gathered information about data sources, analytical methods, and the extent to which threats to validity were discussed.

RESULTS

The search retrieved 83 articles. The most common approach to survival analysis was cause-specific survival (n = 49). Thirty-eight articles measured all-cause survival and 11 measured excess mortality attributable to cancer (relative survival). Three sources of information bias common to all studies (ethnic misclassification, incomplete case ascertainment, and incomplete death ascertainment) were acknowledged in a minority of articles.

CONCLUSIONS

The methodological considerations we present here are shared with studies of cancer survival across other subpopulations. We urge future researchers on this and related topics to clearly describe their data sources, to justify analytic choices, and to fully discuss the potential impact of those choices on the results and interpretation.

Breast cancer diagnosis, patterns of care and burden of disease in Queensland, Australia (1998-2004): does being Indigenous make a difference?

OBJECTIVES

We compared patterns of care, comorbidity, disability-adjusted life-years (DALYs) and survival in Indigenous and non-Indigenous women with breast cancer in Queensland, Australia (1998-2004).

METHODS

A cohort study of Indigenous (n = 110) and non-Indigenous women (n = 105), frequency matched on age and remoteness. We used Pearson's Chi-squared analysis to compare proportions, hazard models to assess survival differences and calculated disability-adjusted life years (DALYs).

RESULTS

Indigenous women were more likely to be socially disadvantaged (43 vs. 20 %, p < 0.01) have comorbidity (42 vs. 18 % p < 0.01), and have regional spread or distant metastasis (metastasis, 51 vs. 36 %, p = 0.02) than non-Indigenous women; there was no difference in treatment patterns. More Indigenous women died in the follow-up period (p = 0.01). DALY's were 469 and 665 per 100,000 for Indigenous and non-Indigenous women, respectively, with a larger proportion of the burden attributed to premature death among the former (63 vs. 59 %).

CONCLUSIONS

Indigenous women with breast cancer received comparable treatment to their non-Indigenous counterparts. The higher proportion of DALYs related to early death in Indigenous women suggests higher fatality with breast cancer in this group. Later stage at diagnosis and higher comorbidity presence among Indigenous women reinforce the need for early detection and improved management of co-existing disease.

Association of type 2 diabetes genetic variants with breast cancer survival among Chinese women

Objective

To evaluate whether the genetic susceptibility of T2D was associated with overall survival (OS) and disease-free survival (DFS) outcomes for breast cancer (BC).

Methods

Included in the study were 6346 BC patients who participated in three population-based epidemiological studies of BC and were genotyped with either GWAS or Exome-chip. We constructed a genetic risk score (GRS) for diabetes using risk variants identified from the GWAS catalog (http://genome.gov/gwastudies) that were associated with T2D risk at a minimum significance level of P ≤ 5.0E-8 among Asian population and evaluated its associations with BC outcomes with Cox proportional hazards models.

Results

During a median follow-up of 8.08 years (range, 0.01–16.95 years), 1208 deaths were documented in 6346 BC patients. Overall, the diabetes GRS was not associated with OS and DFS. Analyses stratified by estrogen receptor status (ER) showed that the diabetes GRS was inversely associated with OS among women with ER- but not in women with ER+ breast cancer; the multivariable adjusted HR was 1.38 (95% CI: 1.05–1.82) when comparing the highest to the lowest GRS quartiles. The association of diabetes GRS with OS varied by diabetes status (P for interaction <0.01). In women with history of diabetes, higher diabetes GRS was significantly associated with worse OS, with HR of 2.22 (95% CI: 1.28–3.88) for the highest vs. lowest quartile, particularly among women with an ER- breast cancer, with corresponding HR being 4.59 (95% CI: 1.04–20.28). No significant association between the diabetes GRS and OS was observed across different BMI and PR groups.

Conclusions

Our study suggested that genetic susceptibility of T2D was positively associated with total mortality among women with ER- breast cancer, particularly among subjects with a history of diabetes. Additional studies are warranted to verify the associations and elucidate the underlying biological mechanism.

A retrospective cohort study of patients with stomach and liver cancers: the impact of comorbidity and ethnicity on cancer care and outcomes

BACKGROUND

Comorbidity has an adverse impact on cancer survival partly through its negative impact on receipt of curative treatment. Comorbidity is unevenly distributed within populations, with some ethnic and socioeconomic groups having considerably higher burden. The aim of this study was to investigate the inter-relationships between comorbidity, ethnicity, receipt of treatment, and cancer survival among patients with stomach and liver cancer in New Zealand.

METHODS

Using the New Zealand Cancer Registry, Māori patients diagnosed with stomach and liver cancers were identified (n = 269), and compared with a randomly selected group of non-Māori patients (n = 255). Clinical and outcome data were collected from medical records, and the administrative hospitalisation and mortality databases. Logistic and Cox regression modelling with multivariable adjustment were used to examine the impacts of ethnicity and comorbidity on receipt of treatment, and the impact of these variables on all-cause and cancer specific survival.

RESULTS

More than 70% of patients had died by two years post-diagnosis. As comorbidity burden increased among those with Stage I-III disease, the likelihood that the patient would receive curative surgery decreased (e.g. C3 Index score 6 vs 0, adjusted OR: 0.32, 95% CI 0.13-0.78) and risk of mortality increased (e.g. C3 Index score 6 vs 0, adjusted all-cause HR: 1.44, 95% CI 0.93-2.23). Receipt of curative surgery reduced this excess mortality, in some cases substantially; but the extent to which this occurred varied by level of comorbidity. Māori patients had somewhat higher levels of comorbidity (34% in highest comorbidity category compared with 23% for non-Māori) and poorer survival that was not explained by age, sex, site, stage, comorbidity or receipt of curative surgery (adjusted cancer-specific HR: 1.36, 95% CI 0.97-1.90; adjusted all-cause HR: 1.33, 95% CI 0.97-1.82). Access to healthcare factors accounted for 25-36% of this survival difference.

CONCLUSIONS

Patients with comorbidity were substantially less likely to receive curative surgery and more likely to die than those without comorbidity. Receipt of curative surgery markedly reduced their excess mortality. Despite no discernible difference in likelihood of curative treatment receipt, Māori remained more likely to die than non-Māori even after adjusting for confounding and mediating variables.

Research in cancer care disparities in countries with universal healthcare: mapping the field and its conceptual contours

The paper reviews published studies focused on disparities in receipt of cancer treatments and supportive care services in countries where cancer care is free at the point of access. We map these studies in terms of the equity stratifiers they examined, the countries in which they took place, and the care settings and cancer populations they investigated. Based on this map, we reflect on patterns of scholarly attention to equity and disparity in cancer care. We then consider conceptual challenges and opportunities in the field, including how treatment disparities are defined, how equity stratifiers are defined and conceptualized and how disparities are explained, with special attention to the challenge of psychosocial explanations.

Cancer survival among First Nations people of Ontario, Canada (1968-2007)

We aimed to compare cancer survival in Ontario First Nations people to that in other Ontarians for five major cancer types: colorectal, lung, cervix, breast and prostate. A list of registered or "Status" Indians in Ontario was used to create a cohort of over 140,000 Ontario First Nations people. Cancers diagnosed in cohort members between 1968 and 2001 were identified from the Ontario Cancer Registry, with follow-up for death until December 31st, 2007. Flexible parametric modeling of the hazard function was used to compare the survival experience of the cohort to that of other Ontarians. We considered changes in survival from the first half of the time period (1968-1991) to the second half (1992-2001). For other Ontarians, survival had improved over time for every cancer site. For the First Nations cohort, survival improved only for breast and prostate cancers; it either declined or remained unchanged for the other cancers. For cancers diagnosed in 1992 or later, all-cause and cause-specific survival was significantly poorer for First Nations people diagnosed with breast, prostate, cervical, colorectal (male and female) and male lung cancers as compared to their non-First Nations peers. For female lung cancer, First Nations women appeared to have poorer survival; however, the result was not statistically significant. Ontario's First Nations population experiences poorer cancer survival when compared to other Ontarians and strategies to reduce these inequalities must be developed and implemented.

Inferior survival among Aboriginal children with cancer in Ontario

BACKGROUND

Pediatric cancer distribution and outcomes have not been examined in Canadian Aboriginal children. The objective of this study was to describe the distribution, event-free survival, and overall survival of Aboriginal children with malignancies who reside in Ontario compared with non-Aboriginal children.

METHODS

This population-based study included 10,520 Ontario children (aged <18 years) who were diagnosed with cancer between 1985 and 2011. Patients were identified from the Pediatric Oncology Group of Ontario Networked Information System database. Aboriginal children were identified by self-reported ethnicity or postal code on a Native reserve at diagnosis. Descriptive statistics of the patients were presented and compared using the Fisher exact test. Event-free and overall survival probabilities were calculated for Aboriginal and non-Aboriginal children, described using Kaplan-Meier curves, and compared using log-rank tests.

RESULTS

In total, 65 Aboriginal children and 10,364 non-Aboriginal children with malignancy were identified. The distribution of malignancy type was similar between the 2 groups. There were no significant differences in baseline characteristics, presence of metastatic disease, or treatment approach (clinical trial, standard of care, or individualized protocol) between the groups. The 5e-year event-free survival rate (± standard error) was 56.3% ± 6.2% among Aboriginal children versus 72.8% ± 0.4% among non-Aboriginal children (P = .0042), and the 5-year overall survival rate was 64% ± 6.0% versus 79.3 ± 0.4% (P = .0017), respectively. The cause of death did not vary according to Aboriginal ethnicity.

CONCLUSIONS

Survival was significantly inferior among Aboriginal children who had cancer compared with non-Aboriginal children who had cancer in Ontario. Future studies are required to define the etiology of this disparity, evaluate the issue nationally, and create interventions to improve outcomes for Aboriginal children.

The impact of comorbidity on cancer survival: a review

Background

A number of studies have shown poorer survival among cancer patients with comorbidity. Several mechanisms may underlie this finding. In this review we summarize the current literature on the association between patient comorbidity and cancer prognosis. Prognostic factors examined include tumor biology, diagnosis, treatment, clinical quality, and adherence.

Methods

All English-language articles published during 2002–2012 on the association between comorbidity and survival among patients with colon cancer, breast cancer, and lung cancer were identified from PubMed, MEDLINE and Embase. Titles and abstracts were reviewed to identify eligible studies and their main results were then extracted.

Results

Our search yielded more than 2,500 articles related to comorbidity and cancer, but few investigated the prognostic impact of comorbidity as a primary aim. Most studies found that cancer patients with comorbidity had poorer survival than those without comorbidity, with 5-year mortality hazard ratios ranging from 1.1 to 5.8. Few studies examined the influence of specific chronic conditions. In general, comorbidity does not appear to be associated with more aggressive types of cancer or other differences in tumor biology. Presence of specific severe comorbidities or psychiatric disorders were found to be associated with delayed cancer diagnosis in some studies, while chronic diseases requiring regular medical visits were associated with earlier cancer detection in others. Another finding was that patients with comorbidity do not receive standard cancer treatments such as surgery, chemotherapy, and radiation therapy as often as patients without comorbidity, and their chance of completing a course of cancer treatment is lower. Postoperative complications and mortality are higher in patients with comorbidity. It is unclear from the literature whether the apparent undertreatment reflects appropriate consideration of greater toxicity risk, poorer clinical quality, patient preferences, or poor adherence among patients with comorbidity.

Conclusion

Despite increasing recognition of the importance of comorbid illnesses among cancer patients, major challenges remain. Both treatment effectiveness and compliance appear compromised among cancer patients with comorbidity. Data on clinical quality is limited.

Comorbidities and breast cancer survival: a report from the Shanghai Breast Cancer Survival Study

We investigated the association of major comorbidities with breast cancer outcomes using the Shanghai Breast Cancer Survival Study, a population-based, prospective cohort study of Chinese women diagnosed with breast cancer. Analyses included 4,664 women diagnosed with stage I-III incident breast cancer aged 20-75 years (median age = 51) during 2002-2006. Women were interviewed at 3-11 months post-diagnosis (median = 6.4) and followed up by in-person interviews and linkage with the vital statistics registry. Multivariable hazard ratios (HRs) and (95 % confidence intervals (CIs)) for the associations of comorbidities with breast cancer outcomes were estimated using Cox regression models. After a median follow-up of 5.3 years (range: 0.64-8.9), 647 women died (516 from breast cancer) and 632 recurrence/metastases were documented. The main comorbidities reported included: hypertension (22.4 %), chronic gastritis (14.3 %), diabetes mellitus (6.2 %), chronic bronchitis/asthma (5.8 %), coronary heart disease (5.0 %), and stroke (2.2 %). Diabetes was associated with increased risk of total mortality (adjusted HR: 1.40 (1.06-1.85)) and non-breast cancer mortality (adjusted HR: 2.64 (1.63-4.27)), but not breast cancer-specific mortality (adjusted HR: 0.98 (0.68-1.41)), adjusting for socio-demographics, clinical characteristics, selected lifestyle factors, and other comorbidities. Women with a history of stroke had a non-significant increased risk of total mortality (adjusted HR: 1.42 (0.91-2.22)) and a significant increased risk of non-breast cancer mortality (adjusted HR: 2.52 (1.33-4.78)), but not breast cancer-specific mortality (adjusted HR: 0.78 (0.38-1.62)). Overall, none of the comorbidities investigated were significantly associated with recurrence. In this large prospective cohort of breast cancer survivors, diabetes was significantly associated with increased risk of total and non-breast cancer mortality, and history of stroke was associated with increased risk of non-breast cancer mortality.

Racial and ethnic differences in health status and health behavior among breast cancer survivors--Behavioral Risk Factor Surveillance System, 2009

PURPOSE

Differences in health status and behavioral risk factors may explain racial/ethnic breast cancer disparities. We examined racial/ethnic differences in health status and behaviors among female breast cancer survivors compared to females without breast cancer.

METHODS

Using cross-sectional data from the 2009 Behavioral Risk Factor Surveillance System, a national state-based, random sample telephone survey, we explored differences in self-rated health, obesity and selected behaviors (physical activity, smoking, alcohol use, fruit, and vegetable consumption) among females aged 18 years and older, who reported a previous breast cancer diagnosis (survivors, n = 10,035) and those who reported no breast cancer history (n = 234,375) by race/ethnicity. Adjusted prevalences of health status and behaviors, accounting for sociodemographics, comorbidities and health care access, were estimated by race/ethnicity.

RESULTS

Compared to all other racial/ethnic groups, more white females reported heavy alcohol consumption and more black females reported obesity regardless of their breast cancer status. Among breast cancer survivors, more whites (33.7 %) were former smokers compared to blacks (24.5 %), "others" (20.5 %), and Hispanics (16.2 %) (p = 0.001). Racial/ethnic differences in obesity also varied by reported time since diagnosis (p value = 0.018). Among long-term survivors (diagnosed >5 years before interview), more black survivors (34.8 %) reported obesity compared to white survivors (23.0 %). Also, among "other" race survivors, long-term survivors (22.0 %) reported more obesity than survivors diagnosed less than 5 years before interview (7.8 %).

CONCLUSIONS

These findings suggest opportunities to increase health behaviors and reduce racial disparities among breast cancer survivors.

IMPLICATIONS FOR CANCER SURVIVORS

Engaging in healthy behaviors can play a significant role in enhancing health outcomes and quality of life of breast cancer survivors. More research is needed to better understand racial differences in obesity, smoking and alcohol consumption in order to develop effective, culturally appropriate interventions to promote a healthy lifestyle after a breast cancer diagnosis.