TYPES OF BREAST CANCER

Breast cancer can arise from various types of tissue that make up breast tissue in various parts of the breast.

Breast cancer can arise from the tissue types that make up breast tissue in various parts of the breast. The primary tissues that make up breast tissue are milk ducts, milk glands/lobules, or the supporting tissue (stroma) between them.

The uncontrolled proliferation of all these tissue types is called breast cancer. Pathological types of breast cancer are named according to the cells in these tissue types. Accordingly, there are many types of breast cancer and various classifications based on these types.
Below, you can find some of the known tissue types of breast cancer and their brief descriptions.

*Ductal carcinoma in situ (DCIS)
Ductal carcinoma in situ (DCIS) is a type of breast cancer confined to the ducts (milk ducts). It is one of the early stages of breast cancer. It is not life-threatening. Breast cancer has not penetrated the basement membrane and therefore has not reached the breast parenchyma and, therefore, the lymphatic channels. Therefore, it cannot metastasize. DCIS is the most common non-invasive type of breast cancer. If it progresses, it can become invasive.

*Invasive ductal carcinoma (IDC)
This is the most common breast cancer. Approximately 80% of breast cancers are IDC. It can be defined as cancer that has penetrated the milk duct wall and extended into the breast tissue.
IDC has several specific subtypes based on their location under the microscope.
Some of these have a better prognosis than IDC.
• Adenoid cystic (or adenocystic) carcinoma
• Low-grade adenosquamous carcinoma (a type of metaplastic carcinoma)
• Medullary carcinoma
• Mucinous (or colloid) carcinoma
• Papillary carcinoma
• Tubular carcinoma
Some subtypes have the same or worse prognosis as IDC. ,
•    Metaplastic carcinoma (most types, including spindle cell and squamous cell types)
•    Micropapillary carcinoma
•    Mixed carcinoma (sharing features of both invasive dulli and lobular carcinoma)
Generally, all subtypes are treated the same as IDC.

*Lobular carcinoma in situ (LCIS)
Despite the word "cancer" in its name, it is not a true cancer. It might be more accurate to say it has a higher risk of developing cancer. It is thought to increase the risk of developing breast cancer by up to three times over the next decades. Therefore, it can also be called "lobular neoplasia." It occurs 90% of the time before menopause. It is more common near menopause. It is usually undetectable on mammograms. Diagnosis is usually made through incidental biopsies. It does not require surgery, radiation, or chemotherapy. Hormone therapy or mastectomy may be performed for prophylaxis. Taking the premenopausal modulatory drug tamoxifen or raloxifene afterward has been shown to reduce the risk of breast cancer in patients with LCIS. Studies have shown that tamoxifen reduces the risk by up to 40%.

*Invasive lobular carcinoma (ILC)
Approximately 10% of breast cancers are ILC, and it is the second most common type of breast cancer. Cancer cells accumulate around the milk ducts but do not distort their shape. It is more difficult to detect on mammography than IDC. While the probability of occurrence in both breasts is 10-15%, the probability is higher than IDC. Therefore, breast MRI is necessary for staging.

*NOS
*Inflammatory breast cancer
*Paget disease of the nipple
*Metastasis to the breast
*Phyllodes tumor
*Angiosarcoma