As we mentioned in the previous post, there are two types of classifications for cancer: molecular and histological, today we will focus on the second one. With histological types we refer to the location of these tumors within the breast and whether they are invasive to other parts of the body or not.
· Carcinoma: any cancer that begins in the skin or other tissues (including breast tissue) that cover or line internal organs
· Milk ducts: these are the “pipes” that transport milk from the milk-producing lobules to the nipple
· Lobules: milk-producing glands located at the ends of the mammary ducts
Breast cancer can begin in different areas of the breast: the ducts, the lobules or in the intermediary tissue.
Ductal carcinoma in situ (DCIS) is the most common type of non-invasive breast cancer. Ductal refers to the fact that it begins within the milk ducts and is “non-invasive” because it doesn’t spread outside the milk duct to other breast tissues (in situ). This carcinoma isn’t life-threatening, but having it can increase the risk of later developing invasive cancer.
Invasive ductal carcinoma (ICD) is the most common type. It represents 80% of all cases of breast cancer. Unlike the previous one, in this case the cancer has invaded the breast tissues that surround it. It begins in the milk ducts (ductal), but spreads. If it isn’t diagnosed in time, it can spread to the lymph nodes or even to other areas of the body.
Lobular carcinoma in situ (LCIS) is a zone of abnormal cell growth, but it isn’t considered breast cancer. It is a sign that the person has a higher risk of developing breast cancer in the future. These abnormal cells begin to grow in the lobules and being in situ means that they don’t spread to other tissues, they stay in the lobules.
Invasive lobular carcinoma (CLI) is the second most common type of breast cancer after invasive ductal carcinoma. About 10% of cancers are of this type. Cancer begins in the milk-producing lobules, but being invasive, it spreads to other tissues. Over time, an invasive lobular carcinoma can spread to the lymph nodes and possibly other areas of the body.
Apart from these types, which are the most common, there are other types of cancer that are a minority and that occur in a few cases. There are invasive papillary carcinomas, cribriform carcinomas, phylloid tumors of the breasts and subtypes of invasive ductal carcinomas such as tubular, medullary or mucinous. Also inflammatory breast cancer, which is a rare and very aggressive form of cancer, since it tends to multiply and spread rapidly.
*Please note that we are not in a position to give you medical advice. Every case is different and every woman needs specific care. You can refer to your physician if you are seeking medical consultation.
Alcaide & et al. (2021). Clasificación actual del cáncer de mama. Implicación en el tratamiento y pronóstico de la enfermedad
Loibl, S., & Gianni, L. (2017). HER2-positive breast cancer. The Lancet, 389(10087), 2415-2429.