This document discusses breast cancer, including its definition, symptoms, stages, diagnosis, and breast self-examination. Breast cancer is an uncontrolled growth of cells in the breast that can spread through blood and lymph vessels. It most commonly begins in the ducts or lobules of the breast. There are 5 stages of breast cancer ranging from Stage 0 (non-invasive) to Stage 4 (metastatic cancer that has spread to other organs). Diagnosis methods include breast self-examination, cytological analysis, mammography, MRI, ultrasound, and biopsy.