Figure 1.

CONSORT diagram outlining data selection process. A retrospective dataset of 1,800 WSIs from 177 breast cancer patients from Guy's Hospital (London, UK) was retrieved. All WSIs were visually inspected, and WSIs with poor quality or pen marks were removed. Based on the LN section level classification obtained from the patient's histology report and after a visual assessment of all sections pertaining to a single LN, a single LN section level for each LN was selected. WSIs from three LN‐positive breast cancer patients were removed as the histological subtypes for these carcinomas were missing. The final dataset was split into three groups based on histological breast cancer subtype, namely in triple negative (TNBC), HER2‐positive/ER‐negative, and ER‐positive (HER2‐positive and HER2‐negative) breast cancer patients.