Tumors in the breast tend to grow slowly. By the time a lump is large enough to feel, it may have been growing for as long as 10 years. however, some tumors are aggressive and grow much faster. Between 50-75 percent of breast cancers begin in the milk ducts, about 10-15 percent begin in the lobules and a few begin in other breast tissues.
The first symptom of breast cancer most women notice is a lump or an area of thickened tissue in their breast.
