Onco Breast Cancer Detection System: Explainable Deep Learning Framework for Ultrasound-Based Breast Cancer Diagnosis

Breast cancer remains one of the most common and life-threatening diseases affecting women worldwide. Early detection significantly increases survival rates and improves treatment outcomes. However, manual diagnosis using ultrasound images requires experienced radiologists and may lead to diagnostic variability. This paper proposes an AI-driven breast cancer detection system that combines deep learning classification with explainable artificial intelligence techniques to assist medical professionals in early diagnosis. The proposed system utilizes a Convolutional Neural Network (CNN) trained on the BUSI Breast Ultrasound dataset to classify images into three categories: benign, malignant, and normal. To improve model transparency, Grad-CAM explainability is integrated to visualize the regions of ultrasound images that influence the model's prediction. A real-time Streamlit dashboard enables clinicians to upload ultrasound images, obtain predictions, visualize heatmaps, and generate downloadable diagnostic reports. Experimental results show that the proposed model achieves high classification accuracy and strong performance across evaluation metrics including precision, recall, and F1-score. Grad-CAM explanations provide interpretable insights that improve trust in AI-assisted diagnosis. The system demonstrates how combining deep learning with explainable AI can support clinicians in early breast cancer detection and improve healthcare decision- making.