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Comparison of Use of Neoadjuvant Systemic Treatment for Breast Cancer and Short-term Outcomes Before vs During the COVID-19 Era in Ontario, Canada

Educational Objective
To identify the key insights or developments described in this article
1 Credit CME
Key Points

Question  Did the use of neoadjuvant-intent systemic therapy for patients with breast cancer change after the emergence of COVID-19 in Ontario, Canada?

Findings  In this cohort study including 10 920 patients, the use of neoadjuvant-intent chemotherapy and hormonal treatment increased during the COVID-19 era, but there was substantial regional variability. Bridging hormonal therapy was a more common adaptation to cancer treatment in the COVID-19 era than neoadjuvant chemotherapy; neoadjuvant-intent systemic treatment was not associated with short-term outcomes in the COVID-19 era.

Meaning  These findings suggest that patients with breast cancer were more likely to receive neoadjuvant-intent systemic treatment in the COVID-19 era to offset delays in surgical capacity.


Importance  In response to an increase in COVID-19 infection rates in Ontario, several systemic treatment (ST) regimens delivered in the adjuvant setting for breast cancer were temporarily permitted for neoadjuvant-intent to defer nonurgent breast cancer surgical procedures.

Objective  To examine the use and compare short-term outcomes of neoadjuvant-intent vs adjuvant ST in the COVID-19 era compared with the pre–COVID-19 era.

Design, Setting, and Participants  This was a retrospective population-based cohort study in Ontario, Canada. Patients with cancer starting selected ST regimens in the COVID-19 era (March 11, 2020, to September 30, 2020) were compared to those in the pre–COVID-19 era (March 11, 2019, to March 10, 2020). Patients were diagnosed with breast cancer within 6 months of starting systemic therapy.

Main Outcomes and Measures  Estimates were calculated for the use of neoadjuvant vs adjuvant ST, the likelihood of receiving a surgical procedure, the rate of emergency department visits, hospital admissions, COVID-19 infections, and all-cause mortality between treatment groups over time.

Results  Among a total of 10 920 patients included, 7990 (73.2%) started treatment in the pre–COVID-19 era and 7344 (67.3%) received adjuvant ST; the mean (SD) age was 61.6 (13.1) years. Neoadjuvant-intent ST was more common in the COVID-19 era (1404 of 2930 patients [47.9%]) than the pre–COVID–19 era (2172 of 7990 patients [27.2%]), with an odds ratio of 2.46 (95% CI, 2.26-2.69; P < .001). This trend was consistent across a range of ST regimens, but differed according to patient age and geography. The likelihood of receiving surgery following neoadjuvant-intent chemotherapy was similar in the COVID-19 era compared with the pre–COVID-19 era (log-rank P = .06). However, patients with breast cancer receiving neoadjuvant-intent hormonal therapy were significantly more likely to receive surgery in the COVID-19 era (log-rank P < .001). After adjustment, there were no significant changes in the rate of emergency department visits over time between patients receiving neoadjuvant ST, adjuvant ST, or ST only during the ST treatment period or postoperative period. Hospital admissions decreased in the COVID-19 era for patients who received neoadjuvant ST compared with adjuvant ST or ST alone (P for interaction = .01 for both) in either setting.

Conclusions and Relevance  In this cohort study, patients were more likely to start neoadjuvant ST in the COVID-19 era, which varied across the province and by indication. There was limited evidence to suggest any substantial impact on short-term outcomes.

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Article Information

Accepted for Publication: June 13, 2022.

Published: August 2, 2022. doi:10.1001/jamanetworkopen.2022.25118

Open Access: This is an open access article distributed under the terms of the CC-BY License. © 2022 Habbous S et al. JAMA Network Open.

Corresponding Author: Steven Habbous, PhD, Ontario Health (Cancer Care Ontario), 525 University Ave, Toronto, Ontario M5G 2L3, Canada (Steven.Habbous@ontariohealth.ca).

Author Contributions: Ms Tai and Dr Habbous had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.

Concept and design: Habbous, Beca, Raphael, Crespo, Eskander, Singh, Gavura, Dai, Irish, Krzyzanowska, Naipaul, Peacock, Forbes, Chan.

Acquisition, analysis, or interpretation of data: Habbous, Tai, Beca, Arias, Raphael, Parmar, Crespo, Cheung, Eisen, Eskander, Singh, Trudeau, Krzyzanowska, Lapointe-Shaw, Peacock, Yeung, Forbes, Chan.

Drafting of the manuscript: Habbous, Raphael, Eskander, Singh, Irish.

Critical revision of the manuscript for important intellectual content: All authors.

Statistical analysis: Habbous, Tai, Eskander, Singh, Peacock.

Obtained funding: Beca, Eskander, Chan.

Administrative, technical, or material support: Habbous, Beca, Arias, Eskander, Singh, Gavura, Irish, Naipaul, Yeung.

Supervision: Habbous, Crespo, Cheung, Eskander, Singh, Irish, Peacock, Forbes.

Conflict of Interest Disclosures: Dr Krzyzanowska reported grants from EISAI, Exelixis, and Lilly; and personal fees from Ipsen Advisory Board and Lilly Advisory Board outside the submitted work. No other disclosures were reported.

Funding/Support: This work was funded by the COVID-19 Research Initiative grant from the Sunnybrook Foundation and Sunnybrook Research Institute.

Role of the Funder/Sponsor: The funder did not influence the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; or decision to submit the manuscript for publication.

Disclaimer: Parts of this material are based on data and information compiled and provided by the Canadian Institute of Health Information (CIHI). However, the analyses, conclusions, opinions, and statements expressed herein are those of the author, and not necessarily those of CIHI. All views expressed are those of the authors of this report and do not necessarily reflect those of Ontario or the Ministry.

Additional Contributions: We acknowledge support of the Ministry of Health and Long-Term Care in this report.

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