In a breast biopsy, cells are removed from a suspicious mass in the breast. These cells are then examined to find breast cancer cells. Biospies can determine if a mass is cancerous or benign. Based on the type of mass, you may have a fine needle aspiration, core biopsy, sentinel node biopsy, or another type. Follow the links below to find WebMD's comprehensive coverage about how breast biopsies are done, what to expect, what the results mean, and more.