Identification of molecular cell type of breast cancer on digital histopathology images using deep learning and multiplexed fluorescence imaging

ER, PR (estrogen, progesterone receptor), and HER2 (human epidermal growth factor receptor 2) status are assessed using immunohistochemistry and reported in standard clinical workflows as they provide valuable information to help treatment planning. The protein Ki67 has also been suggested as a prognostic biomarker but is not routinely evaluated clinically due to insufficient quality assurance. The routine pathological practice usually relies on small biopsies, such that the reduction in consumption is necessary to save materials for special assays. For this purpose, we developed and validated an automatic system for segmenting and identifying the (ER, PR, HER2, Ki67) positive cells from haematoxylin and eosin (H&E) stained tissue sections using multiplexed immunofluorescence (MxIF) images at cellular level as a reference standard. In this study, we used 100 tissue-microarray cores sampled from 56 cases of invasive breast cancer. For ER, we extracted cell nucleus images (HoverNet) from the H&E images and assigned each cell nucleus as ER positive vs. negative based on the corresponding MxIF signals (whole cell segmentation with DeepCSeg) upon H&E to MxIF image registration. We trained a Res-Net 18 and validated the model on a separate test-set for classifying the cells as positive vs. negative for ER, and performed the same experiment for the other three markers. We obtained area-under-the-receiver-operating-characteristic-curves (AUCs) of 0.82 (ER), 0.85 (PR), 0.75 (HER2), 0.82 (Ki67) respectively. Our study demonstrates the feasibility of using machine learning to identify molecular status at cellular level directly from the H&E slides.