The application of artificial intelligence and machine learning to automate Gleason grading: Novel tools to develop next generation risk assessment assays.
170 Background: Postoperative risk assessment remains an important variable in the treatment of prostate cancer (PCA). Advances in genomic risk classifiers have aided clinical-decision making; however, clinical-pathologic variables such as Gleason grade and pathologic stage remain significant comparators for accurate prognostication. We aimed to standardize the descriptive pathology of PCA through automation of Gleason grading with artificial intelligence and image analysis feature selection Methods: Retrospective study using radical prostatectomy (RP) tissue microarrays from Henry Ford Hospital and Roswell Park Cancer Center with 8-year median follow-up. Samples were stained with a multiplex immunofluorescent assay: Androgen Receptor (AR), Ki67, Cytokeratin 18, Cytokeratin 5/6 and Alpha-methylacyl-CoA racemase); imaged with a CRI Nuance FX camera and then analyzed with proprietary software to generate a suite of morphometric - attributes that quantitatively characterize the Gleason spectrum. Derived features were univariately correlated with disease progression using the concordance index (CI) along with the hazards ratio and p-value. Results: Starting with a training cohort of 306 patients and a 15% event rate, MIF PCA images were subjected to a machine learning analysis program which incorporates a graph theory-based approach for characterization of gland / ring fusion and fragmentation of tumor architecture (TA) with biomarker quantitation (BQ) (i.e. AR and Ki67). 19 unique image features with 7 TA and 12 TA+BQ were identified, by univariate CI, all TA features were strongly associated with Gleason grading with CI’s reflecting degree of tumor differentiation (CI 0.29-.33, p-value = 0.005). Four TA+BQ features were selected in a training risk model and effectively replaced the clinical Gleason features. By comparison, dominant RP Gleason had a CI of 0.31. Conclusions: Image-based feature selection guided by principles of machine learning has the potential to automate and replace traditional Gleason grading. Such approaches provide the necessary foundation for next generation risk assessment assays.