Breast cancer is a cancer that occurs in the cells of the breast. There are several types of breast cancer, and the kind depends on which cells in the breast turn malignant. After skin cancer, breast cancer is the second most diagnosed cancer in women in the country. However, breast cancer can occur in women as well as men, but is more common in women. Read on to learn more about breast cancer. Symptoms A lump or mass that feels as small as a pea Change in the contour, shape, or size of the breast Marble-like hardened area underneath the skin Redness of the skin on the nipple or breast Change in the feel or look of the skin on the nipple or breast A thickening or lump in or near the breast or in the underarm, which persists through the menstrual cycle Clear fluid discharge or blood-stain from the nipple The area looks distinctly different from other areas on the breast Newly inverted nipple Some people might not notice any breast cancer signs, so it is vital to undergo routine mammograms. Causes The precise cause for breast cancer is unknown. However, sometimes it is inherited. It is known as hereditary breast cancer.