Breast cancer is caused due to cell mutation in the breast cells. Usually, different types of breast cancer attack the lobules, the milk-producing glands, or ducts, a tube that carries the milk to the nipples. Sometimes, cancer may also affect fatty tissue or fibrous connective tissue within your breast. In the final stages, cancer cells start affecting the healthy breast tissue and get inside the lymph nodes, under the arms.
The lymph nodes are the primary carriers of cancer to the rest of the body.
1. Breast cancer types
Breast cancer can be divided into two types: invasive, noninvasive or in situ. While invasive cancer spreads from the breast ducts or glands to other parts of the breast, noninvasive cancer does not spread far from the original affected tissue. The different types of breast cancer include:
- DCIS or ductal carcinoma in situ is a type of cancer that remains confined to the ducts in the breast. It does not reach the surrounding breast tissue.
- LCIS or lobular carcinoma in situ proliferates in the milk-producing glands of the breast. Like DCIS, the cancer cells do not affect the surrounding tissues.
- Invasive ductal carcinoma starts affecting the milk ducts and then proliferates to the surrounding tissue in the breast. Once the cancer reaches the milk ducts, it spreads to the other organs and tissue.
- ILC or invasive lobular carcinoma affects the lobules and then starts spreading to the surrounding breast tissue.
2. Lesser known types
Some of the lesser-known types of breast cancer include Paget’s disease, Phyllodes tumor, and Angiosarcoma. The types of breast cancer are divided into several stages based on the tumor size and how much it has spread. Breast cancer is categorized into 5 main stages (0 to 4):
- Stage 0
It remains confined to the breast ducts and does not reach the surrounding tissue.
- Stage 1A
The primary tumor is 2 centimeters wide or less and does not reach the lymph nodes.
- Stage 1B
Cancer is located in the lymph nodes. A tumor smaller than 5cm may be found. The treatment involves surgery (lumpectomy and mastectomy) depending on the size and location, radiation, chemotherapy, and hormone therapy.
- Stage 2A
The tumor is smaller than 2cm and reaches 1–3 nearby lymph nodes; the size is between 2 and 5cm and does not reach the lymph nodes.
- Stage 2B
The tumor is 2 to 5cm long and affects the 1–3 axillary (armpit) lymph nodes. Sometimes, the tumor is larger than 5cm and the lymph nodes remain unaffected. Treatment recommended include surgery, chemotherapy, and/or a combination of targeted therapy, radiation, and hormone treatment.
- Stage 3A
Cancer reaches 4–9 axillary lymph nodes or affects mammary lymph nodes.
- Stage 3B
A tumor reaches the chest wall or skin and may affect 9 lymph nodes.
- Stage 3C
Cancer affects 10 or more axillary lymph nodes, lymph nodes around the collarbone, or the internal mammary nodes.The treatment is similar to stage 2.
- Stage 4 breast cancer
Cancer cells affect near and distant lymph nodes and distant organs. The size of the tumor could vary. This type of breast cancer treatment involves multiple therapies to combat metastatic cancer.