Area-based disparities in breast cancer screening participation in British Columbia

Secondary prevention techniques (e.g., screening mammography) allow for early detection of cancer and reduction in mortality at the population level.[1] In Canada, the Canadian Task Force on Preventive Health Care recommends that average-risk women aged 50 to 74 years be screened for breast cancer with mammography every 2 to 3 years.[2] Despite well-documented evidence of the benefits of screening mammography, uptake often falls short of targets.[3]

During a public health emergency such as the one brought about by the COVID-19 pandemic, when preventive services are likely to see a drop in volume, any underlying disparities in screening uptake in various subpopulations may be exacerbated. Internationally, it has been reported that disproportionately low breast cancer screening participation is seen among women experiencing cultural or immigration-related barriers or in medically underserved communities in the United States.[4,5] There is also growing evidence that breast cancer screening rates in Canada vary based on geographic location,[6] demographics,[7,8] and socioeconomic status.[9,10] To provide local insights into screening service use by specific subpopulations in BC, we applied an equity lens to investigate breast cancer screening participation rates among BC women of screening age, examining the data for various geographic, demographic, and socioeconomic levels.

A collaboration of the Provincial Health Services Authority’s (PHSA’s) programs, the BCCDC’s Population and Public Health, and BC Cancer examined the 30-month breast cancer screening participation rate of BC women aged 50 to 69 years using data from the BC Cancer Breast Screening Mammography. We included all records of women aged 50 to 69 with a valid six-digit BC postal code in service provided during the 30-month period between 1 July 2009 and 31 December 2011. By means of postal code translation, we assigned a unique census dissemination area (DA), health service delivery area (HSDA), and health authority (HA) to each record. By linking screening data with DA-level demographic as well as socioeconomic data derived from Census Plus 2011,[11] we examined disparities in breast cancer screening participation among BC women aged 50 to 69 years across HSDAs, across income and education quintiles, and across quintiles of social and material deprivation [Figure]. We found that during the study period:

• The breast cancer screening participation rate for BC women aged 50 to 69 years ranged from 40% to 56% across the HSDAs. Lowest rates were observed in the Northwest, Northeast, and Kootenay Boundary, and highest rates were observed in Central Vancouver Island and Okanagan.
• Women aged 50 to 69 years in lower education and income groups had lower breast cancer screening participation rates than those of higher education and income levels. The income disparity was consistent with more current published data.[7]
• The most materially deprived groups of women (50 to 69 years) had lower breast cancer screening participation rates compared with the least deprived groups.

Our findings provide important local evidence of disparities in cancer screening participation when we consider demographic, geographic, and socioeconomic factors. This information may help to inform targeted intervention strategies to improve cancer preventive care across BC.

—Li Rita Zhang, MPH
BCCDC, PHSA
—Drona Rasali, PhD, FACE 
BCCDC, PHSA, UBC School of Population and Public Health
—Ryan Woods, PhD 
BC Cancer, PHSA, Simon Fraser University Faculty of Health Sciences
—Janette Sam, RTR
BC Cancer, PHSA
—Lisa Kan, MSc
BC Cancer, PHSA

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This article is the opinion of the BC Centre for Disease Control and has not been peer reviewed by the BCMJ Editorial Board.

References

1.    Coldman A, Phillips N, Wilson C, et al. Pan-Canadian study of mammography screening and mortality from breast cancer. J Natl Cancer Inst 2014;106:dju261.

2.    Canadian Task Force on Preventive Health Care. Published guidelines. Accessed 23 July 2020. https://canadiantaskforce.ca/guidelines/published-guidelines.

3.    BC Cancer. BC Cancer breast screening 2018 program results. Accessed 11 August 2020. www.bccancer.bc.ca/screening/Documents/082019_Breast%20Annual%20Report2019_V20191025.pdf.

4.    Miller BC, Bowers JM, Payne JB, Moyer A. Barriers to mammography screening among racial and ethnic minority women. Soc Sci Med 2019;239:112494.

5.    Vang S, Margolies LR, Jandorf L. Mobile mammography participation among medically underserved women: A systematic review. Prev Chronic Dis 2018;15:180291.

6.    Olson RA, Nichol A, Caron NR, et al. Effect of community population size on breast cancer screening, stage distribution, treatment use and outcomes. Can J Public Health 2012;103:46-52.

7.    Woods RR, McGrail KM, Kliewer EV, et al. Breast screening participation and retention among immigrants and non-immigrants in British Columbia: A population-based study. Cancer Med 2018;7:4044-4067.

8.    Vahabi M, Lofters A, Kim E, et al. Breast cancer screening utilization among women from Muslim majority countries in Ontario, Canada. Prev Med 2017;105:176-183.

9.    Chan W, Yun L, Austin PC, et al. Impact of socio-economic status on breast cancer screening in women with diabetes: A population-based study. Diabet Med 2014;31:806-812.

10.    Meshefedjian GA, Ouimet M-J, Frigault L-R, et al. Association of material deprivation status, access to health care services, and lifestyle with screening and prevention of disease, Montreal, Canada, 2012. Prev Chronic Dis 2016;13:160157.

11.    Rasali D, Kao D, Fong D, Qiyam L. Priority health equity indicators for British Columbia: Preventable and treatable mortality, 2009–2013. Vancouver, BC: BC Centre for Disease Control, Provincial Health Services Authority. Accessed 12 August 2020. www.bccdc.ca/Our-Services-Site/Documents/premature-mortality-indicator-report.pdf.