Breast cancer classification

Breast cancer classification' involves categorizing breast cancers based on different factors, including the cancer's morphology, genetic makeup, and response to therapy. This classification aids in determining the prognosis and the most effective treatment strategies for patients. Breast cancer is a heterogeneous disease, meaning it has many subtypes that require different management approaches.

Types of Breast Cancer Classification

By Histopathology

Breast cancer can be classified based on its histological appearance, which is observed under a microscope after a biopsy or surgery. The main types include:

• Ductal Carcinoma In Situ (DCIS): A non-invasive cancer where abnormal cells are found in the lining of a breast duct.
• Invasive Ductal Carcinoma (IDC): The most common type of breast cancer, starting in the milk ducts and invading surrounding tissues.
• Invasive Lobular Carcinoma (ILC): Cancer that begins in the lobules (milk-producing glands) and spreads to surrounding tissues.
• Inflammatory Breast Cancer (IBC): A rare and aggressive form of breast cancer that causes swelling and redness in the breast.

By Receptor Status

Breast cancers are also classified based on the presence or absence of three receptors known to fuel most breast cancer growth:

• Estrogen Receptor-positive (ER+): Cancers that have receptors for estrogen.
• Progesterone Receptor-positive (PR+): Cancers that have receptors for progesterone.
• HER2-positive: Cancers that have an excess of the HER2 protein on their surface.

Cancers lacking these receptors are termed Triple-negative breast cancer (TNBC), which tend to be more aggressive and have fewer treatment options.

By Genetic Profile

Advancements in genomic testing have led to the classification of breast cancer based on its genetic makeup. The most well-known test, Oncotype DX, helps predict a patient's risk of cancer recurrence and whether they will benefit from chemotherapy. Breast cancers can also be classified into subtypes based on gene expression profiles, such as Luminal A, Luminal B, HER2-enriched, and Basal-like.

Staging

Breast cancer staging is crucial for determining the extent of the disease and guiding treatment decisions. The TNM system, which stands for Tumor size, Node involvement, and Metastasis, is commonly used. Stages range from 0 (non-invasive) to IV (metastatic cancer).

Treatment Implications

The classification of breast cancer significantly influences treatment choices. Hormone receptor-positive cancers may be treated with hormone therapy, while HER2-positive cancers can be targeted with HER2 inhibitors. Triple-negative breast cancers, lacking targeted therapies, are usually treated with chemotherapy.

Prognosis

The prognosis of breast cancer varies widely depending on its classification. Generally, early-stage, hormone receptor-positive cancers have a better prognosis than advanced, triple-negative or HER2-positive cancers.

Future Directions

Research is ongoing to refine breast cancer classification and discover new biomarkers that can guide treatment. Personalized medicine, which tailors treatment to the individual characteristics of each patient's cancer, is the ultimate goal.