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. 2023 Jan;197(1):161-175.
doi: 10.1007/s10549-022-06732-y. Epub 2022 Nov 5.

Changes in breast cancer treatment during the COVID-19 pandemic: a Dutch population-based study

Anouk H Eijkelboom  1   2 , Linda de Munck  1 , C Willemien Menke-van der Houven van Oordt  3 , Mireille J M Broeders  4   5 , Desiree H J G van den Bongard  6 , Luc J A Strobbe  7 , Marc A M Mureau  8 , Marc B I Lobbes  9   10   11 , Pieter J Westenend  12 , Linetta B Koppert  13 , Agnes Jager  14 , Ester J M Siemerink  15 , Jelle Wesseling  16   17 , Helena M Verkooijen  18 , Marie-Jeanne T F D Vrancken Peeters  19   20 , Marjolein L Smidt  21 , Vivianne C G Tjan-Heijnen  22 , Sabine Siesling  23   24 ; NABON-COVID-19 Consortium; COVID and Cancer Care-NL Consortium
Collaborators, Affiliations

Changes in breast cancer treatment during the COVID-19 pandemic: a Dutch population-based study

Anouk H Eijkelboom et al. Breast Cancer Res Treat. 2023 Jan.

Abstract

Purpose: We aimed to compare (1) treatments and time intervals between treatments of breast cancer patients diagnosed during and before the COVID-19 pandemic, and (2) the number of treatments started during and before the pandemic.

Methods: Women were selected from the Netherlands Cancer Registry. For aim one, odds ratios (OR) and 95% confidence intervals (95%CI) were calculated to compare the treatment of women diagnosed within four periods of 2020: pre-COVID (weeks 1-8), transition (weeks 9-12), lockdown (weeks 13-17), and care restart (weeks 18-26), with data from 2018/2019 as reference. Wilcoxon rank-sums test was used to compare treatment intervals, using a two-sided p-value < 0.05. For aim two, number of treatments started per week in 2020 was compared with 2018/2019.

Results: We selected 34,097 women for aim one. Compared to 2018/2019, neo-adjuvant chemotherapy was less likely for stage I (OR 0.24, 95%CI 0.11-0.53), stage II (OR 0.63, 95%CI 0.47-0.86), and hormone receptor+/HER2- tumors (OR 0.55, 95%CI 0.41-0.75) diagnosed during transition. Time between diagnosis and first treatment decreased for patients diagnosed during lockdown with a stage I (p < 0.01), II (p < 0.01) or III tumor (p = 0.01). We selected 30,002 women for aim two. The number of neo-adjuvant endocrine therapies and surgeries starting in week 14, 2020, increased by 339% and 18%, respectively. The number of adjuvant chemotherapies decreased by 42% in week 15 and increased by 44% in week 22.

Conclusion: The pandemic and subsequently altered treatment recommendations affected multiple aspects of the breast cancer treatment strategy and the number of treatments started per week.

Keywords: Breast cancer; Breast cancer care; COVID-19; Treatment.

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Conflict of interest statement

Financial interests: HMV received funding by the Dutch Cancer Foundation, European Commission, ZonMw. MLS received grants from Servier Pharma and Nutricia. JW received funding from the Cancer Research UK KWF Dutch Cancer Society ZonMW and the Antoni van Leeuwenhoek Foundation. Non-financial interests: JW is a member of the Scientific Advisory Board Dutch Expert Centre for Screening. All other authors have no relevant financial or non-financial interests to disclose.

Figures

Fig. 1
Fig. 1
Dutch COVID-19 timeline of 2020, GP general practitioner
Fig. 2
Fig. 2
Flow chart of group 1 and 2
Fig. 3
Fig. 3
Time interval (median, 95% confidence interval) between a diagnosis and surgery (excluding patients with an invasive tumor receiving neo-adjuvant treatment), b diagnosis and start of neo-adjuvant treatment, c diagnosis and start of first treatment (of any kind), d end of neo-adjuvant treatment and surgery, e surgery and start of adjuvant treatment, and f surgery and start of radiotherapy, for patients diagnosed between week 1 of 2018 and week 26 of 2020 (group 1). Time intervals are stratified by period of diagnosis and tumor stage. Pre-COVID: weeks 1–8, 2020; Transition: weeks 9–12, 2020; Lockdown: weeks 13–17, 2020; Care restart: weeks 18–26, 2020. *significantly different time interval in that period of 2020 compared to 2018/2019 (p < 0.05)
Fig. 4
Fig. 4
Percentage change in the 3-week moving average of the number of patients (group 2) starting a neo-adjuvant chemotherapy, b neo-adjuvant endocrine therapy, c neo-adjuvant targeted therapy, d surgery, e breast-conserving surgery, f mastectomy, g mastectomy with immediate breast reconstruction, h adjuvant chemotherapy, i adjuvant endocrine therapy, j adjuvant targeted therapy, or k adjuvant radiotherapy. 3-week moving average was calculated over the week of interest and the two weeks preceding this week Percentage change calculated as the percentage of the corresponding three-week moving average of 2018/2019
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