Breast cancer is cancer that develops in breast cells. Typically, the cancer forms in either the lobules or the ducts of the breast.
Lobules are the glands that produce milk, and ducts are the pathways that bring the milk from the glands to the nipple. Cancer can also occur in the fatty tissue or the fibrous connective tissue within your breast.
The uncontrolled cancer cells often invade other healthy breast tissue and can travel to the lymph nodes under the arms. The lymph nodes are a primary pathway that helps the cancer cells move to other parts of the body.
In its early stages, it may not cause any symptoms. In many cases, a tumour may be too small to be felt, but an abnormality can still be seen on a mammogram.
If a tumour can be felt, the first sign is usually a new lump in the breast that was not there before. However, not all lumps are cancer.
Each type of cancer can cause a variety of symptoms. Many of these symptoms are similar, but some can be different. Symptoms for the most common cancers include:
- a breast lump or tissue thickening that feels different than surrounding tissue and has developed recently
- breast pain
- red, pitted skin over your entire breast
- swelling in all or part of your breast
- a nipple discharge other than breast milk
- bloody discharge from your nipple
- peeling, scaling, or flaking of skin on your nipple or breast
- a sudden, unexplained change in the shape or size of your breast
- inverted nipple
- changes to the appearance of the skin on your breasts
- a lump or swelling under your arm
If you have any of these symptoms, it doesn’t necessarily mean you have cancer. For instance, pain in your breast or a breast lump can be caused by a benign cyst.
Still, if you find a lump in your breast or have other symptoms, you should see your doctor for further examination and testing.
There are several types of this cancer, and they’re broken into two main categories: “invasive” and “noninvasive,” or in situ.
While invasive cancer has spread from the breast ducts or glands to other parts of the breast, noninvasive cancer has not spread from the original tissue.
These two categories are used to describe the most common types, which include:
- Ductal carcinoma in situ. Ductal carcinoma in situ (DCIS) is a noninvasive condition. With DCIS, the cancer cells are confined to the ducts in your breast and haven’t invaded the surrounding breast tissue.
- Lobular carcinoma in situ. Lobular carcinoma in situ (LCIS) is a cancer that grows in the milk-producing glands of your breast. Like DCIS, the cancer cells haven’t invaded the surrounding tissue.
- Invasive ductal carcinoma. Invasive ductal carcinoma (IDC) is the most common type of this cancer. This type of cancer begins in your breast’s milk ducts and then invades nearby tissue in the breast. Once this cancer has spread to the tissue outside your milk ducts, it can begin to spread to other nearby organs and tissue.
- Invasive lobular carcinoma. Invasive lobular carcinoma (ILC) first develops in your breast’s lobules and has invaded nearby tissue.