Impact of the COVID-19 Pandemic in the United States on First-Line Treatment Trends in Metastatic Breast Cancer

2020 Year in Review - Breast Cancer

During the COVID-19 pandemic, there was a decline in the number of patients beginning first-line treatment. There was a decrease in the percentage of patients receiving CDK4/6 inhibitor combination therapy while a simultaneous increase in endocrine monotherapy was observed.

More than 18 million cases of COVID-19 and more than 300,000 deaths related to COVID-19 have been confirmed in the United States as of late December 2020.1

Healthcare providers have needed to adopt new procedures to safely interact with and manage treatment for oncology patients in light of a strained healthcare system, quarantine orders, and national social distancing guidelines. The American Society of Breast Surgeons COVID-19 Pandemic Breast Cancer Consortium recommendations have suggested some patients be considered for dose or schedule adjustments to ongoing treatment to mitigate the risk for side effects and frequency of healthcare visits while deferring invasive procedures and beginning treatments with less need for monitoring or side-effect risk. This study’s objective was to assess whether during the pandemic patients with metastatic breast cancer were facing changes in treatment in routine clinical practice in the United States.

This retrospective cohort study analyzed patients aged >18 years with a new metastatic breast cancer diagnosis receiving treatment between January 1, 2019, and April 30, 2020. Electronic health records from more than 280 cancer clinics and more than 800 sites of care, representing approximately 2.4 million patients with cancer who are actively being treated for their disease, are included.

For the study cohort, first-line treatments were assessed monthly and stratified by new and continuously treated patients in a given month. Types of first-line treatment included chemotherapy, endocrine monotherapy, CDK4/6 regimen, and other treatments (eg, targeted monotherapy).

A total of 2680 patients with metastatic breast cancer were included in the analysis, based on eligibility. Of these, 99% were female, the median age at metastatic diagnosis was 60 years, and 60% of the patients were white. De novo metastatic disease at diagnosis was reported as 34%, and most patients received treatment at a community clinic. The most common breast cancer subtype was hormone receptor–positive, human epidermal growth factor receptor 2–negative (66%).

The number of patients starting first-line therapy decreased from 121 to 100 (17%) between March and April 2020, while the number of continuing patients decreased from 837 to 817 (2%).

The percentage of newly diagnosed patients being prescribed a CDK4/6 regimen averaged 35% between January 2019 and March 2020 and decreased to 29% in April. The percentage of newly diagnosed patients being prescribed endocrine monotherapy declined from 37% in January 2019 to 22% in March 2020 (averaging 27% across this period). In April, the largest month-to-month variation was detected in the endocrine monotherapy–use group, when the percentage of new patients increased to 28%. Across the study months among continuing patients, treatment distributions appeared stable.

The investigators concluded that during the early stage of the COVID-19 pandemic, there was a decline in the number of patients beginning first-line treatment, and they observed a decrease in the percentage of patients receiving CDK4/6 inhibitor combination therapy while seeing an increase in endocrine monotherapy prescriptions between March and April 2020. Clinicians modified management of metastatic breast cancer with treatment initiation delays and shifts in prescribing patterns for patients beginning new therapies. Continuing follow-up to assess these trends through the course of the pandemic is intended to monitor whether these shifts are prolonged and persistent. In the United States, this may help to identify demographic and clinical variables associated with disparities in treatment at different stages of the COVID-19 epidemic.

Source: Kurosky K, Liu X, Meche A, et al. First-line treatment trends in metastatic breast cancer before and at the early stage of the COVID-19 pandemic in the United States. Presented at: 2020 San Antonio Breast Cancer Symposium, December 8-11, 2020. Abstract PS11-21.

1. Centers for Disease Control and Prevention. CDC COVID Data Tracker. Accessed December 23, 2020.

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