Invasive breast cancer
Invasive breast cancer (also called infiltrating breast cancer) has spread to the normal tissues within or surrounding the breast, or to other parts of the body through the blood and lymph systems.
There are two main types of invasive breast cancer:
- Invasive ductal carcinoma (IDC): IDC begins in the milk ducts and accounts for 70 percent or more of invasive breast cancers.
- Invasive lobular carcinoma (ILC): ILC begins in the lobules and is more rare. Sometimes, the origin of the tumor may not be known.
Sometimes, breast cancer can be both invasive and noninvasive: some of the cancer cells have grown into normal tissue and some has remained in the ducts or lobules. This type of cancer is treated as an invasive cancer. In some invasive breast cancers, malignant cells may be present in both the ducts and lobues. This type of “mixed tumor” breast cancer is usually treated as ductal carcinoma.
Invasive breast cancer is the most common type of breast cancer among American women. According to the American Cancer Society, 246,660 new cases of invasive breast cancer will be diagnosed in women in 2016.
Invasive breast cancer subtypes
There are also several subtypes of invasive breast cancer, including:
- Endocrine-sensitive breast cancer: Breast cancer cells contain measurable amounts of estrogen or progesterone receptors, making the cancer treatable with hormonal therapies
- HER2-positive breast cancer: Breast cancer cells contain excess amounts of the HER2 receptor, making the cancer treatable with anti-HER2 targeted therapies
- Triple-negative breast cancer: Breast cancer cells do not contain receptors for estrogen, progesterone, or HER2. This type of cancer cannot be treated with hormonal or anti-HER2 therapy, but can be treated with chemotherapy, radiation, and non-HER2 targeted therapy.
- Inflammatory breast cancer: Invasive cancer in which there is no lump or tumor.
- Medullary carcinoma: A less common type of IDC where the tumor is soft and fleshy (resembling the medulla in the brain).
- Metaplastic carcinoma: A rare type of invasive breast cancer where a portion of the tumor cells have changed to a different type of breast cancer (a mixed tumor)
- Mucinous carcinoma: A less common type of IDC, the tumors create thick pools of mucin, a main component of saliva.
- Papillary carcinoma: A rare type of IDC that forms in distinct lumps with finger-like projections.
- Tubular carcinoma: A less common type of IDC made of collections of small, tube-like cells less than 1 cm in diameter.
- Paget’s disease: Any of the above forms of breast cancer that directly involves the nipple.
- Male breast cancer: A rare form of breast cancer, accounting for less than one percent of all breast cancers. Breast cancer in men usually begins as a lump or mass in a man’s breast, and is most commonly treated with a mastectomy or lumpectomy.
Invasive breast cancer treatment options
Treatment for invasive breast cancer usually involves some combination of breast-conserving surgery or mastectomy, radiation therapy, chemotherapy, hormone therapy and/or targeted therapy. The specific treatments involved and the order of the therapies largely depends on the stage and characteristics of the tumor.