Definition of breast cancer: Cancer that forms in tissues of the breast. The most common type of breast cancer is ductal carcinoma, which begins in the lining of the milk ducts (thin tubes that carry milk from the lobules of the breast to the nipple). Another type of breast cancer is lobular carcinoma, which begins in the lobules (milk glands) of the breast. Invasive breast cancer is breast cancer that has spread from where it began in the breast ducts or lobules to surrounding normal tissue. Breast cancer occurs in both men and women, although male breast cancer is rare. Estimated new cases and deaths from breast cancer in the United States in 2013:
- New cases: 232,340 (female); 2,240 (male)
- Deaths: 39,620 (female); 410 (male)
About 1 in 8 women born today in the United States will get breast cancer at some point during her life. After skin cancer, breast cancer is the most common kind of cancer in women.
The third Friday in October each year is National Mammography Day, first proclaimed by President Clinton in 1993. On this day, or throughout the month, women are encouraged to make a mammography appointment.