Background: The COVID 19 pandemic has disrupted all aspects of healthcare, including the diagnosis and treatment of breast cancer. In March 2020, the Society of Surgical Oncology, the American College of Surgeons, and the American Society of Breast Surgeons issued guidelines regarding the timing of surgery for cancer patients to preserve hospital resources and minimize exposure of patients and staff to COVID 19. Recommendations included delaying breast cancer surgery if possible, and using neoadjuvant chemotherapy or neoadjuvant endocrine therapy to treat selected patients while waiting for definitive surgery. In California, the “shelter in place” (SiP) order began March 17, 2020, and both screening mammography and elective surgeries were stopped in a large, integrated health care system. We evaluated the impact of these operational changes on the presentation and treatment of breast cancer patients in our system.Methods:We performed a retrospective review of patients newly diagnosed between 3/17/20, the starting date of SiP, and 5/18/20, when elective operations resumed in our system. We compared this cohort to patients who were diagnosed between 3/17/19 and 5/18/19. Age, histology, anatomic staging features, grade, receptor status, and initial treatment were compared between the cohorts. For the patients who underwent surgery, we compared the time from biopsy to time to surgery (TTS) and the type of operation. Comparisons involving categorical variables were performed using the chi-square test. Normally-distributed continuous variables were compared using two sample-t-tests. P-values of <0.05 were considered statistically significant.Results:There were 790 patients in the 2019 cohort and 279 in the 2020 cohort. There were no significant differences in age at presentation, histologic subtypes, nodal status, or operation type between the two groups. The T-stages at presentation of the 2020 group were higher than those of the 2019 group; 29% presented with T1c tumors in 2020 vs 26% in 2019, and 37% with T2 tumors in 2020 vs 30% in 2019 (p=0.03). A higher percentage of patients presented with distant metastatic disease at the time of diagnosis in 2020 (7% in 2020 vs 2% in 2019, p<0.001), although the absolute numbers of patients were similar (19 patients in 2020 vs 17 patients in 2019). Of patients with invasive breast cancer, a higher percentage of patients presented with grade 3 tumors in 2020 (35% in 2020 vs 24% in 2019, p=0.002), and triple negative tumors (15% vs 10%, p=0.02). Fewer patients underwent surgery first in 2020 (73% in 2020 vs 85% in 2019, p<0.001) and more underwent neoadjuvant chemotherapy (13% in 2020 vs 9% in 2019, p=0.03). Only 4% of the 2020 surgery group had been placed on neoadjuvant endocrine therapy while awaiting definitive surgery. The TTS for patients with surgery as the initial treatment was significantly shorter for the 2020 group (mean 22 days in 2020 vs 31 days in 2019, p<0.001).Conclusions: Without screening mammography, newly-diagnosed patients in a large, integrated health care system during the COVID 19 pandemic presented with more advanced and aggressive breast cancers as compared to the equivalent time period in 2019. Fewer patients underwent surgery first, and more underwent neoadjuvant chemotherapy. The TTS for breast cancer patients in 2020 was significantly shorter than in 2019, which we hypothesize was due to the availability of operating rooms since elective operations had been stopped. This study demonstrates the ability of a large, integrated health care system to deliver timely breast cancer care to patients presenting with symptomatic disease during the constraints of the COVID 19 pandemic, and highlights the importance of screening in the early detection of breast cancer.

Citation Format: Sharon B. Chang, Alison C. Savitz, Brooke Vuong, Annie Tang, Margaret Mentakis, Amy M. Miller, Veronica C. Shim, Gillian E. Kuehner. Characterization of breast cancer management during the COVID 19 pandemic in a large integrated healthcare delivery system: Stage at diagnosis and timing/modality of first treatment [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr SS2-06.