Prostate cancer tissue classification by multiphoton imaging, automated image analysis and machine learning.

Prostate carcinoma, a slow-growing and often indolent tumour, is the second most commonly diagnosed cancer among men worldwide. The prognosis is mainly based on the Gleason system through prostate biopsy analysis. However, new treatment and monitoring strategies depend on a more precise diagnosis. Here we present results by multiphoton imaging for prostate tumour samples from 120 patients that allow to obtain quantitative parameters leading to specific tumour aggressiveness signatures. An automated image analysis was developed to recognise and quantify stromal fibre and neoplastic cell regions in each image. The set of metrics was able to distinguish between non-neoplastic tissue and carcinoma areas by linear discriminant analysis and random forest with an accuracy of 89 ± 3%, but between Gleason groups of only 46 ± 6%. The reactive stroma analysis improved the accuracy to 65 ± 5%, clearly demonstrating that stromal parameters should be considered as additional criteria for a more accurate diagnosis.