BACKGROUND: The B-MaP-C study aimed to determine alterations to breast cancer (BC) management during the peak transmission period of the UK COVID-19 pandemic and the potential impact of these treatment decisions .
METHODS: This was a national cohort study of patients with early BC undergoing multidisciplinary team (MDT) -guided treatment recommendations during the pandemic, designated 'standard' or 'COVID-altered', in the preoperative, operative and post-operative setting . FINDINGS: Of 3776 patients (from 64 UK units) in the study , 2246 (59 %) had 'COVID-altered' management . 'Bridging' endocrine therapy was used (n = 951) where theatre capacity was reduced . There was increasing access to COVID-19 low-risk theatres during the study period (59 %). In line with national guidance, immediate breast reconstruction was avoided (n = 299). Where adjuvant chemotherapy was omitted (n = 81), the median benefit was only 3% (IQR 2-9 %) using 'NHS Predict' . There was the rapid adoption of new evidence-based hypofractionated radiotherapy (n = 781, from 46 units). Only 14 patients (1 %) tested positive for SARS-CoV-2 during their treatment journey .
CONCLUSIONS: The majority of 'COVID-altered' management decisions were largely in line with pre-COVID evidence-based guidelines, implying that breast cancer survival outcomes are unlikely to be negatively impacted by the pandemic . However, in this study, the potential impact of delays to BC presentation or diagnosis remains unknown.