Automatic high-grade cancer detection on prostatectomy histopathology images
Progress in Biomedical Optics and Imaging - Proceedings of SPIE
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Automatic cancer grading and high-grade cancer detection for radical prostatectomy (RP) specimens can benefit pathological assessment for prognosis and post-surgery treatment decision making. We developed and validated an automatic system which grades cancerous tissue as high-grade (Gleason grade 4 and higher) vs. low-grade (Gleason grade 3) on digital histopathology whole-slide images (WSIs). We combined this grading system with our previouslyreported cancer detection system to build a high-grade cancer detection system which automatically finds high-grade cancerous foci on WSIs. The system was tuned on a 3-patient data set and cross-validated against expert-drawn contours on a separate 68-patient data set comprising 286 mid-gland whole-slide images of RP specimens. The system uses machine learning techniques to classify each region of interest (ROI) on the slide as cancer or non-cancer and each cancerous ROI as high-grade or low-grade cancer. We used leave-one-patient-out cross-validation to measure the performance of cancer grading for classified ROIs with three different classifiers and the performance of the high-grade cancer detection system on a per tumor focus basis. The best performing (Fisher) classifier yielded an area under the receiver-operating characteristic curve of 0.87 for cancer grading. The system yielded error rates of 19.5% and 23.4% for pure high-grade (Gleason 4+4, 5+5) and high-grade (Gleason Score ≥ 7) cancer detection, respectively. The system demonstrated potential for practical computation speeds. Upon successful multi-centre validation, this system has the potential to assist the pathologist to find high-grade cancer more efficiently, which benefits the selection and guidance of adjuvant therapy and prognosis post RP.