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Types of breast cancer (Part I)

The detection of breast cancer doesn’t have a single diagnosis or treatment. Although the first thing that usually comes to mind is the word "chemotherapy", the treatment will depend on the type of cancer.

There are two types of classifications for cancer: histological and molecular. But there isn’t correlation of the histological types with any molecular group. 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. And with the molecular subtypes we refer to the origin of the cancer.

In this first part we will focus the article on molecular types and in the next we will talk about histological types.

We distinguish three molecular types: luminal, triple negative and HER2 positive.

Luminal breast cancer means that it develops in the inner (or luminal) cells, which are the cells that line the breast ducts. This type of cancer is the most common, representing 75-80% of breast tumors. These tumors express at least one type of hormone receptor (estrogen or progesterone). Within this group there are two types:

· Luminal A. Represents 50-70% of luminal cases. It is the subtype with the best prognosis and the lowest risk of relapse. It is usually treated with a hormonal treatment, acting on these hormonal receptors.

· Luminal B. It represents 10-20% of the luminals. It has a higher expression of proliferation and cell cycle genes (Ki67), which means that this type of tumor proliferates at a higher rate than type A

HER2 positive It has a worse diagnosis than the luminal one. Being HER2 positive means that the person has this protein when tested. This HER2 protein promotes the growth of cancer cells.

Triple negative Represents 10-15% of breast cancers. The behavior of this tumor is aggressive and with high recurrence rates. It is called triple negative because tests are negative on all three types of receptors mentioned above: estrogen, progesterone, and HER2. It’s common in women with BRCA1 gene mutations, perimenopausal women and women under 40 years of age.

*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.

Weigelt, B., Geyer, F. C., & Reis-Filho, J. S. (2010). Histological types of breast cancer: how special are they?. Molecular oncology, 4(3), 192-208.

Cáncer de mama - SEOM: Sociedad Española de Oncología Médica © 2019.

Cáncer de mama HER2 negativo: Descripción, tratamiento y pronóstico.


Tipos de cáncer de mama.