Objectives

Our study sought to assess the impact of the COVID-19 pandemic and resultant lockdown measures on the staging of incident breast cancer diagnoses in the United States, using data from 2018-2021.

Methods

We conducted a retrospective analysis of medical chart data provided by Guardian Research Network. Adult patients were eligible for inclusion if they received an inpatient/outpatient breast cancer code [ICD-10 C50] from 01/01/2018-12/31/2020. Patients with pre-existing cancer diagnoses (C00-C96) recorded within two years were excluded.

The number of new cancer cases was descriptively analyzed, alongside cancer stage at diagnosis for a subset of patients, by triangulating TNM measurements, physician staging assessments and C77-79 codes recorded within the index/subsequent quarter.

Results

Overall, 6,639 patients (mean age: 62.75; 99.16% female) were identified. Minor fluctuations in the average number of new diagnoses per quarter were observed over time (2018: 507.25; 2019: 580.75; 2020: 571.75). A drop in new diagnoses was detected during the second quarter of 2020 (412), however relatively stable numbers were observed during all other quarters in 2020 (mean: 625; range: 586-646).

A total of 587 and 491 patients from 2019 and 2020 were included in follow-up cancer staging analyses. Differences in the distribution of new diagnoses by stage were consistent across most quarters in 2019 and 2020. Nonetheless, only 23.38% of patients received Stage 1 cancer diagnoses during the second quarter in 2020, as compared to 34.01% in 2019. The proportion of patients with stage 2/3 diagnoses was consistent across both years, while the share of stage 4 diagnoses was higher in the second quarter of 2020 (32.47% versus 22.45%).

Conclusions

The pandemic’s impact on breast cancer diagnoses was particularly pronounced during the second quarter of 2020, corresponding with fewer overall cases and more severe prognoses, with potential links to delayed care and/or constricted access to healthcare services.