E75: Breast Cancer in the Immediate Aftermath of COVID-19: Bigger Tumors, More Positive Nodes, Same Surgery.

The COVID-19 pandemic was associated with an unprecedented decrease in the incidence of diagnosed breast cancers in 2020 and is expected to be associated with advanced stage at presentation in the post-pandemic era. The epidemiological natural history of breast cancers diagnosed during the pandemic is still not fully understood. The primary objective of this study is to compare stage at presentation and biological tumor characteristics of breast cancers treated before and after the initial phase of the COVID pandemic.

Methods:

A multi-institution retrospective chart review was performed of patients diagnosed with ductal carcinoma in situ and invasive breast cancers within a single health care system between March-August 2019 (pre-pandemic) and March-August 2021 (post-acute phase pandemic). Differences in clinical features were compared using chi-square, Fisher’s exact tests, and odds ratios.

Results:

381 patients were identified in the 2019 pre-pandemic cohort and 558 were identified the 2021 post-pandemic cohort. Patients in 2021 had a larger mean tumor size (17.9 mm vs 14.5 mm, p=0.0002), more tumors >2 cm (OR 1.48, p=0.0476), more grade 3 tumors (OR 1.29, 0.046), and higher nodal stage with significantly fewer patients having negative nodes in the latter group (see table). There were no differences in age at diagnosis, presence of a palpable finding, tumor subtype, receptor subtype, type of surgery, and receipt of axillary dissection or neoadjuvant therapy. And despite higher nodal stage, there was no significant difference in overall pathologic stage. Of note, patients in 2021 were more likely to have >24 months since their last imaging test (p=0.0007) and less likely to have their breast cancer detected by screening breast MRI (OR 0.36, p=0.016).

Conclusions:

Breast cancer diagnosed in the immediate post-pandemic period was associated with larger tumors, a greater incidence of grade 3 tumors, and more advanced nodal disease.  Despite this, surgical treatment delivered did not significantly change, most likely related to wider adoption of performing no further axillary surgery in those with 1-2 positive nodes. Further research is warranted, including patients who did not revert back to yearly screening even after 2021 to determine the overall effect of COVID-19 on breast cancer screening, detection, and treatment.