The ducts and the lobules are the two structures of the breast where cancer is most likely to occur. Your doctor can look under a microscope at the cancer cells that were collected during your biopsy to determine which type of cancer you have. The type of cancer partly determines your choices for treatment. Other rare types of cancers, such as inflammatory breast cancer and Paget’s disease, can begin in the breast as well.
The single most important factor in evaluating any breast cancer is determining whether it is noninvasive (in situ) or invasive (infiltrating). This will help determine your treatment path and, to some extent, your expectations for results.
Noninvasive cancers occur only in the ducts or lobules and do not spread to the surrounding areas. They can later develop into a more serious, invasive type of cancer. If you are diagnosed with noninvasive carcinoma, your chances of surviving are very high if you don’t wait to treat it. If you do wait, you run the risk that your cancer will become invasive. Invasive cancer is more difficult to treat.
Invasive cancers have started to spread to surrounding areas. This type of breast cancer is much more serious than noninvasive cancer. It often invades nearby lymph nodes first. It can then spread to other parts of your body through your bloodstream and lymphatic system. Treatment for invasive cancer is usually a more difficult, long-term process. But these cancers often can still be cured.
Ductal carcinoma is the most common type of breast cancer. It is breast cancer that starts in the lining of the breast ducts. When breast cancer has not spread outside of the ducts, it is called ductal carcinoma in situ (DCIS). Sometimes called intraductal carcinoma, it’s the most common type of noninvasive breast cancer. Invasive ductal carcinoma is breast cancer that has spread beyond the walls of the breast ducts. It is the most common type of invasive breast cancer.
A diagnosis of DCIS is relatively good news. It means that abnormal cells are found only inside the milk duct of the breast and that these abnormal cells have not spread outside the duct. They also have not spread within the breast, beyond the breast, to the lymph nodes under the arm, or to other parts of the body. DCIS can be in either a small portion or a large portion of a duct system. DCIS has an extremely high cure rate--more than 90%. But if it isn’t removed, some types of DCIS may change over time and turn into invasive cancers. You can reduce your risk of getting the more serious, invasive breast cancers by getting the proper treatment for DCIS.
Lobular Carcinoma in situ (LCIS)
LCIS is a noncancerous (benign) growth change in some of the cells in the milk glands, called lobules. Although its name implies otherwise, it is not considered a true cancer and does not require treatment. But it does mean you may have an increased risk of getting ductal breast cancer or invasive lobular carcinoma in the future.
Invasive Lobular Carcinoma
Fewer people get lobular carcinoma than ductal carcinoma. This cancer starts in the lobules and has spread outside of the lobules. It requires treatment.
Paget’s disease is a rare cancer that begins in the milk ducts of your nipple. It grows slowly. Therefore, it often doesn’t get diagnosed and treated until it is advanced. Occurring in only one nipple, Paget’s disease causes symptoms which are similar to those you might have for a skin infection. Symptoms may include:
If you have any of these symptoms, especially for more than a few days, see a doctor.