Health Topics

Types of Breast Cancer

Most Common Types of Breast Cancer

Like most cancers, breast cancer exists in different forms. The most common types of breast cancer include:

Infiltrating (invasive) ductal carcinoma

  • This cancer starts in the milk ducts of the breast. It then breaks through the wall of the duct and invades the surrounding tissue in the breast. This is the most common form of breast cancer, accounting for 80% of cases.

Ductal carcinoma in situ is ductal carcinoma in its earliest stage (stage 0)

  • In situ refers to the fact that the cancer hasn't spread beyond its point of origin. In this case, the disease is confined to the milk ducts and has not invaded nearby breast tissue. If untreated, ductal carcinoma in situ may become invasive cancer. It is almost always curable.

Infiltrating (invasive) lobular carcinoma

  • This cancer begins in the lobules of the breast where breast milk is produced, but has spread to surrounding tissues or the rest of the body. It accounts for 10% to 15% of breast cancers and can be more difficult to diagnose with mammograms.

Lobular carcinoma

  • Lobular carcinoma in situ is a marker for cancer that is only in the lobules of the breast. It isn't a true cancer, but serves as a marker for the increased risk of developing breast cancer later, possibly in both or either breasts. Thus, it is important for women with lobular carcinoma in situ to have regular clinical breast exams and mammograms.

Cancers can also form in other parts of the breast but are less common. For more information on breast cancer, download the Free Breast Cancer Treatment Guide.