Early breast cancer is cancer that is contained in the breast and may or may not have spread to the lymph nodes in the breast or armpit. Some cancer cells may have spread outside the breast and armpit area, but cannot be detected.
Early breast cancer can be treated successfully, and most women diagnosed and treated for early breast cancer will not die from the disease.
How does breast cancer develop?
We don’t know exactly how long breast cancer takes to develop, but it usually grows slowly. It can be several years before a breast cancer becomes big enough to be detected.
Breast cancer starts in the ducts or lobules of the breast. The lobules produce milk when a woman breastfeeds, and the milk travels down the milk ducts to the nipple. Over years, the cells that line the lobules or ducts in the breast can increase in number. If the cells become abnormal in shape and size, and if they multiply in an uncontrolled way, they are called cancer cells.
If the cancer cells are contained within the ducts of the breast this is called ductal carcinoma in situ (DCIS).
If the cancer cells spread outside the ducts or lobules of the breast into the surrounding tissue, this is called invasive breast cancer. Early breast cancer is an invasive breast cancer. Invasive cancer cells sometimes spread outside the breast area to other parts of the body. They do this by moving through blood vessels, such as veins, or through lymphatic vessels. Lymphatic vessels are next to veins in the body, and are connected to lymph nodes (glands). Lymph nodes collect normal fluid and dead cells from the lymphatic vessels. Lymph nodes can enlarge for many reasons, including an infection or cancer. In breast cancer, the lymph nodes in the axilla (the armpit) are usually the first site that the cancer will spread to outside the breast. These are the lymph nodes usually referred to throughout this book. Occasionally, breast cancer cells first spread to lymph nodes in other locations, such as the internal mammary lymph nodes, located under the breastbone.
If the cancer has spread to one or more lymph nodes in the armpit, but is otherwise contained within the breast, then the cancer is ‘early breast cancer’. If the cancer has spread to places near the breast, such as the chest (including the skin, muscles or bones of the chest), but the cancer isn’t found in other areas of the body, this is called locally advanced breast cancer. If the cancer cells spread from the breast and are found in other areas of the body, such as the bones or the lungs, this is called metastatic breast cancer.
