Early diagnosis of breast cancer, the most common disease among women around the world, increases the chance of treatment and is highly important. Nuclear atypia grading in histopathological images plays an important role in the final diagnosis and grading of breast cancer. Grading images by pathologists is a time consuming and subjective task. Therefore, the existence of a computer-aided system for nuclear atypia grading is very useful and necessary. In this study, two automatic systems for grading nuclear atypia in breast cancer histopathological images based on deep learning methods are proposed. A patch-based approach is introduced due to the large size of the histopathological images and restriction of the training data. In the proposed system I, the most important patches in the image are detected first and then a three-hidden-layer convolutional neural network (CNN) is designed and trained for feature extraction and to classify the patches individually. The proposed system II is based on a combination of the CNN for feature extraction and a twolayer Long short-term memory (LSTM) network for classification. The LSTM network is utilised to consider all patches of an image simultaneously for image grading. The simulation results show the efficiency of the proposed systems for automatic nuclear atypia grading and outperform the current related studies in the literature.
K E Y W O R D S breast cancer, CNN, histopathological image, LSTM networks, nuclear atypia
| INTRODUCTIONBreast cancer is caused due to an outgrowth of abnormal cells in the breast. This disease is the second leading cause of death among women around the world [1] and is a serious problem for most human societies. Early diagnosis of this disease increases the chance of efficient treatment. After performing mammography and ultrasound imaging, if abnormal tissues are found, a biopsy examination is required. In this test, a small sample of the breast tissue is placed under a microscope to acquire histopathological images for further investigation. Histopathology refers to the visual examination of tissue [2]. Histopathological images are available in digital format which is analysed to detect the type and grade of cancer [3]. Various magnifications of histological images are available such as 10X, 20X and 40X.Traditional methods for grading breast cancer are manually performed by pathologists. Pathologists examine histologicalThis is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.