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

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.

Fig. 1

Dutch COVID-19 timeline of 2020, GP general practitioner

Fig. 2

Flow chart of group 1 and 2

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

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