Breast Cancer: Risk Factors, Symptoms & Treatment

Medically Reviewed by Dr. Samantha Miller, MBChB

Photo Courtesy: andresr/E+/Getty Images

When malignant cancer cells form and grow within a person's breast tissue, breast cancer occurs. Although it is the most commonly diagnosed cancer in American women, breast cancer can impact people of all genders. The American Cancer Society estimates that over 280,000 women and over 2,600 men will be newly diagnosed with invasive breast cancer in 2021 — and about 43,000 women and 530 men will die from breast cancer.

Here, we'll provide an overview of breast cancer — from the different types to risk factors, symptoms and treatments — to give you a better picture of the disease and its impacts. 

Types of Breast Cancer

Breast cancer is a malignancy in which the cells of the breast divide and grow at a faster-than-typical rate and can, over time, form tumors in the breast. Without treatment, malignant tumors can spread to other parts of the body. 

While most breast cancers start in the milk ducts, some malignancies form first in the glandular tissue. Moreover, many tumors grow slowly: it may take as long as 10 years for a patient to be able to feel the tumor in their breast. However, in some instances, the tumor may be aggressive and grow at a much faster pace. 

What you may not realize is that there are different types of breast cancer. The categorizations refer to the location of the cancer's origin and whether it's considered invasive or non-invasive. Invasive breast cancer refers to cancer cells that have traveled from their original location and have invaded surrounding tissue; in later stages, this type of cancer may spread to the lymph nodes or one's organs. On the other hand, non-invasive cancers, sometimes referred to as “carcinoma in situ,” are confined to the point of origin and have not spread to otherwise healthy tissue.

With this in mind, types of breast cancer include:

  • Ductal Carcinoma In Situ (DCIS): In this most common form of non-invasive breast cancer, making up around 1 in 5 new diagnoses, malignant cells develop inside the milk ducts and remain in place. Although DCIS is not a life-threatening cancer, it can increase your chances of developing invasive cancer later on.
  • Lobular Carcinoma In Situ (LCIS): Like DCIS, LCIS remains within its place of origin and is non-life threatening. LCIS occurs when abnormal cells have developed in the milk-producing glands. LCIS is not thought of as a true form of breast cancer, but an instance of LCIS can put you at a higher risk for developing breast cancer in the future
  • Invasive Ductal Carcinoma (IDC): This form of cancer, sometimes referred to as infiltrating ductal carcinoma, is the most common form of invasive breast cancer, affecting nearly 80% of all patients with invasive breast cancer. IDC begins in the milk ducts but, eventually, the cancer cells will break through the duct walls and attack the surrounding tissue.
  • Invasive Lobular Carcinoma (ILC): ILC is the second-most common form of invasive breast cancer. In an instance of ILC, the cancer cells originate in the milk-producing glands, or lobules, and spread into nearby healthy tissue.

Other rare types of breast cancer include inflammatory breast cancer, angiosarcoma and Paget’s disease.