# COVID-19 impacts on the breast cancer care pathway among systemically marginalized communities in Ontario

## TL;DR

The study found that the pandemic disrupted breast cancer screening and treatment, especially affecting marginalized communities in Ontario.

## Contribution

The study specifically examines how pandemic-related healthcare pauses impacted breast cancer care disparities among immigrant women in Ontario.

## Key findings

- Breast cancer screening rates dropped significantly during the pandemic period.
- Pandemic-era patients were more likely to undergo mastectomy rather than breast-conserving surgery.
- Caribbean women had lower odds of early-stage diagnosis despite higher screening rates before the pandemic.

## Abstract

Healthcare system pauses occurred worldwide due to COVID-19, and may have worsened pre-existing disparities in breast cancer care. In this population-based, retrospective cohort study, we investigated indicators of breast cancer care (i.e., adherence to screening guidelines, early vs. late-stage diagnosis, and mastectomy vs. breast-conserving surgery) before and after COVID-19 lockdowns in Ontario, with an emphasis on immigrant women.

We had three binary outcomes and corresponding cohorts, and each outcome/cohort was ascertained relative to two time periods: April 1, 2018-March 31, 2020 (“pre-pandemic”) and April 1, 2020-March 31, 2022 (“pandemic”): i) up to date on screening, ii) early vs late stage of breast cancer diagnosis, and iii) mastectomy vs breast-conserving surgery at any time after diagnosis for women who were diagnosed at stages I-III during each two-year time period. We conducted descriptive analyses, and used logistic regression, both unadjusted and adjusted, to determine odds ratios for our dichotomous outcomes.

Breast cancer screening rates dropped from 59.4% to 51.0%, and the number of women diagnosed dropped from 18,821 to 14,269, in the pre-pandemic vs pandemic period. In multivariable analyses, screening significantly dropped (AOR = 0.69 [95% CI (0.69–0.69)]), there was no significant difference for diagnostic stage (AOR = 0.99 [95% CI (0.92–1.05)]), and the use of mastectomy vs breast-conserving surgery was higher in the pandemic period (AOR = 1.14 [95% CI (1.08–1.20)]). Women from the Caribbean had lower odds of early-stage diagnosis in the pre-pandemic period despite a screening advantage.

Future work should further explore the reasons for these findings and potential system-level solutions.