Breast cancer is characterized by uncontrolled growth of breast cells. According to the National Cancer Institute, the disease develops when malignant cells form in the tissues of the breast. The most common type, ductal carcinoma, originates in the cells lining the milk ducts, accounting for 70 to 80 percent of all cases. The second most prevalent form, lobular carcinoma, begins in the lobules, representing 10 to 15 percent of diagnoses.
Healthy cells in the body grow, divide, and multiply as needed, and receive signals to die when they are damaged. However, cancer cells, arising from errors in genetic material, defy this process. As Breastcancer.org explains, these abnormal cells not only survive but also continue to divide and multiply even when the body doesn’t require them, ultimately forming a tumor. This tumor can be benign, or malignant.
The breast itself is composed of lobules – glands that produce milk – and ducts that transport it to the nipple. These structures are embedded in fatty tissue, supported by muscles and the chest wall. The lymphatic system, including lymph nodes located in the underarm, above the collarbone, and in the chest, plays a crucial role in filtering lymph and storing white blood cells to combat infection and disease. Cancer can spread through this system.
While breast cancer is most frequently associated with women, it can also occur in men, though It’s rare. In the United States, a woman has approximately a 1 in 8 lifetime risk of developing the disease. The Mayo Clinic notes that cancer can also originate in the glands within the breast, known as lobules, which are designed to produce milk.
The disease’s progression can vary. Sometimes, the spread of cancer is contained, referred to as “in situ.” However, if the cancer extends beyond the breast, it is considered “invasive,” potentially spreading to nearby tissues and lymph nodes, or metastasizing to other parts of the body via the lymphatic system or bloodstream.