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Inter- and intra-provincial variation in screen-detected breast cancer across five Canadian provinces: a CanIMPACT study

Abstract

Objective

Breast cancer screening aims to identify cancers in early stages when prognosis is better and treatments less invasive. We describe inter- and intra-provincial variation in the percentage of screen-detected cases under publicly funded healthcare systems and factors related to having screen- vs non-screen-detected breast cancer across five Canadian provinces.

Methods

Women aged 40+ diagnosed with incident breast cancer from 2007 to 2012 in five Canadian provinces were identified from their respective provincial cancer registries. Standardized provincial datasets were created linking screening, health administrative, and claims data. Province-specific logistic regression models were used to evaluate the association of demographic and healthcare utilization factors in each province with the odds of screen-detected cancer.

Results

There was significant inter- and intra-provincial variation by age. Screen detection ranged from 42% to 52% in ages 50–69 but women aged 50–59 had approximately 4–8% lower screen detection than those aged 60–69 in all provinces. Screening associations with income quintile and rurality varied across provinces. Those least likely to be screen-detected within a province were consistently in the lowest income quintile; OR ranged from 0.62–0.89 relative to highest income quintile/urban patients aged 50–69. Lack of visits to primary care 30 months prior to diagnosis was also consistently associated with lower odds of screen detection (OR range, 0.37–0.76).

Conclusion

Breast cancer screen detection rates in the Canadian provinces examined are relatively high. Associations with income-rurality indicate a need for greater attention and/or targeted outreach to specific communities and/or provincial regions to improve access to breast cancer screening services intra-provincially.

Résumé

Objectif

Le dépistage du cancer du sein vise à repérer les cancers aux stades précoces, quand le pronostic est meilleur et les traitements moins effractifs. Nous décrivons les écarts inter- et intraprovinciaux dans le pourcentage de cas détectés par dépistage dans les systèmes de soins de santé subventionnés par l’État, ainsi que les facteurs liés au fait d’avoir un cancer du sein détecté ou non par dépistage dans cinq provinces canadiennes.

Méthode

Les femmes de 40 ans et plus ayant reçu un diagnostic de cancer du sein incident entre 2007 et 2012 dans cinq provinces canadiennes ont été identifiées grâce au registre des cancers de leur province respective. Nous avons créé des fichiers provinciaux standardisés jumelant les données de dépistage, les données administratives sur la santé et les données sur les demandes de remboursement. Des modèles de régression logistique propres à chaque province ont servi à évaluer l’association entre les facteurs démographiques et d’utilisation des soins de santé dans la province et la probabilité de cancer détecté par dépistage.

Résultats

Nous avons observé des écarts inter- et intraprovinciaux significatifs selon l’âge. La détection par dépistage se situait entre 42 et 52 % chez les femmes de 50 à 69 ans, mais chez les femmes de 50 à 59 ans, dans toutes les provinces, elle était inférieure d’environ 4 à 8 % à celle des femmes de 60 à 69 ans. Les associations entre le dépistage et le quintile de revenu et la ruralité variaient d’une province à l’autre. Les cas les moins susceptibles d’avoir été détectés par dépistage dans une province se trouvaient uniformément dans le quintile de revenu inférieur; le rapport de cotes (RC) était de 0,62–0,89 comparativement aux patientes du quintile de revenu supérieur/vivant en milieu urbain âgées de 50 à 69 ans. L’absence de rendez-vous de soins primaires 30 mois avant le diagnostic était aussi uniformément associée à une moindre probabilité de détection par dépistage (RC, 0,37–0,76).

Conclusion

Les taux de détection du cancer du sein par dépistage dans les provinces canadiennes à l’étude sont relativement élevés. Les associations avec le revenu et la ruralité sont signes qu’une plus grande attention et/ou des activités de sensibilisation ciblées sur certaines communautés et/ou certaines régions provinciales sont nécessaires pour améliorer l’accès aux services de dépistage du cancer du sein à l’intérieur des provinces.

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Acknowledgements

In addition to the authors, the membership of the CanIMPACT Administrative Health Data Group who undertook this work include: Natalie Biswanger, CancerCare Manitoba, Winnipeg, Manitoba; Dongdong Li, BC Cancer Research Centre, Vancouver, British Columbia; Aisha Lofters, University of Toronto, Toronto, Ontario; Sharon Matthias, CanIMPACT Patient Advisory Committee, Alberta; Nicole Mittmann, Cancer Care Ontario, Toronto, Ontario; Rahim Moineddin, University of Toronto, Toronto, Ontario; Geoff Porter, Dalhousie University, Halifax, Nova Scotia; Dawn Powell, CanIMPACT Patient Advisory Committee, Ontario; Donna Turner, CancerCare Manitoba, Winnipeg, Manitoba; Robin Urquhart, Dalhousie University, Halifax, Nova Scotia; Bonnie Vick, CanIMPACT Patient Advisory Committee, Saskatchewan. The authors also thank Emma Shu, Marlo Whitehead, and Yan Zhang for conducting data processing and statistical analyses.

Funding

This work was supported by the Canadian Institutes of Health Research [grant number128272]. The opinions, results and conclusions reported in this paper are those of the authors and are independent from the funder. This study is supported by ICES, which is funded by an annual grant from the Ontario Ministry of Health and Long-Term Care (MOHLTC). No endorsement by ICES or the Ontario MOHLTC is intended or should be inferred. Parts of this material are based on data and information provided by Cancer Care Ontario (CCO). The opinions, results, views, and conclusions reported in this paper are those of the authors and do not necessarily reflect those of CCO. No endorsement by CCO is intended or should be inferred. Parts of this material are based on data and information compiled and provided by the Canadian Institute for Health Information (CIHI). However, the analyses, conclusions, opinions and statements expressed herein are those of the authors, and not necessarily those of CIHI. We gratefully acknowledge CancerCare Manitoba for their ongoing support and Manitoba Health for the provision of data. The results and conclusions presented are those of the authors. No official endorsement by Manitoba Health is intended or should be inferred. Nova Scotia data were provided by Health Data Nova Scotia and the Nova Scotia Department of Health and Wellness, however, the observations and opinions expressed are those of the authors and do not represent those of either Health Data Nova Scotia or the Department of Health and Wellness. Data for this study were also provided by Population Data BC and BC Cancer. All inferences, opinions, and conclusions drawn in this study are those of the authors, and do not reflect the opinions or policies of the BC Data Steward(s).(“BC Cancer Agency Registry Data. V2, Population Data BC: BC Cancer Agency; 2011 [Available from: http://www.popdata.bc.ca/Data.],” n.d.; “Medical Services Plan (MSP) Payment Information File. V2, MOH (2011): British Columbia Ministry of Health; 2011 [Available from: http://www.popdata.bc.ca/Data.],” n.d.; “Consolidation File (MSP Registration & Premium Billing). V2, Population Data BC: British Columbia Ministry of Health (2011); 2011 [Available from: http://www.popdata.bc.ca/Data.],” n.d.)

Author information

Correspondence to Marcy Winget.

Ethics declarations

Research ethics boards and privacy committees approved the study and data stewards approved data access in each province. Data sharing across provinces was not permitted by the provincial data stewards; therefore, distributed data analyses were conducted by the respective provincial teams. Data were linked at the individual level in each province through an encrypted individual health insurance number. Quality assurance and cross checks were performed on datasets during and after data linkage to ensure accuracy and completeness. None of the databases or datasets used in the study are publicly available.

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The authors declare that they have no conflict of interest.

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Winget, M., Yuan, Y., McBride, M.L. et al. Inter- and intra-provincial variation in screen-detected breast cancer across five Canadian provinces: a CanIMPACT study. Can J Public Health (2020). https://doi.org/10.17269/s41997-019-00282-5

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Keywords

  • Breast cancer screening
  • Screen-detected cancer
  • Multi-jurisdictional
  • Administrative data linkage

Mots-clés

  • Dépistage du cancer du sein
  • Cancer détecté par dépistage
  • Plurigouvernemental
  • Jumelage de données administratives