Breast cancer is the most common invasive cancer in females. It is also a leading cause of cancer deaths among females. Cancer starts in the breast and can begin or start in one or both breasts.
Breast cancers can start from different parts of the breast. The breast is an organ that sits on top of the upper ribs and chest muscles. There is a left and right breast and each one has mainly glands, ducts, and fatty tissue. In women, the breast makes and delivers milk to feed newborns and infants. The amount of fatty tissue in the breast determines the size of each breast.
Breast cancer can spread when the cancer cells get into the blood or lymph system and then are carried to other parts of the body.
The lymph (or lymphatic) system is a part of your body’s immune system. It is a network of lymph nodes (small, bean-sized glands), ducts or vessels, and organs that work together to collect and carry clear lymph fluid through the body tissues to the blood. The clear lymph fluid inside the lymph vessels contains tissue by-products and waste material, as well as immune system cells.
The lymph vessels carry lymph fluid away from the breast. In the case of breast cancer, cancer cells can enter those lymph vessels and start to grow in lymph nodes. Most of the lymph vessels of the breast drain into:
- Lymph nodes under the arm (axillary lymph nodes)
- Lymph nodes inside the chest near the breastbone (internal mammary lymph nodes)
- Lymph nodes around the collar bone (supraclavicular [above the collar bone] and infraclavicular [below the collar bone] lymph nodes)
If cancer cells have spread to your lymph nodes, there is a higher chance that the cells could have traveled through the lymph system and spread (metastasized) to other parts of your body. Still, not all women with cancer cells in their lymph nodes develop metastases, and some women with no cancer cells in their lymph nodes might develop metastases later.
There are several types of breast cancer. The most common type is ductal carcinoma, which begins in a milk duct. Another type is lobular carcinoma, which begins in a lobule, one of the tiny glands that produce milk.
“Invasive” breast cancer involves cancerous cells spreading to nearby tissue. It is then more likely that cancer will spread to other parts of the body.
“Noninvasive” breast cancer remains in its place of origin. These cells may eventually become invasive.
There is no way to prevent breast cancer. However, a person can take steps to significantly reduce their risk.
- limiting alcohol consumption, for people who drink
- having a healthy diet with plenty of fresh fruit and vegetables
- getting enough exercise
- maintaining a moderate body mass index
A person who is considering using hormone replacement therapy after menopause may wish to discuss this with a healthcare professional.
For people with a high risk of breast cancer, preventive surgery is also an option.