Breast cancer is a growth of abnormal cells in the breast. The term “invasive breast cancer” means that the cancer cells have spread into the surrounding cells or beyond the breast.

The precancerous condition atypical ductal hyperplasia affects the cells of the breast’s milk ducts. These cells can evolve to become ductal breast cancer, so your doctor will track your breast health carefully.

Although men don’t have breasts, they do have some breast tissue. This means men can develop breast cancer, too. Cases of male breast cancer comprise less than 1 percent of all breast cancers.

Ductal carcinoma in situ (DCIS) starts in the milk ducts and is considered a noninvasive or preinvasive breast cancer. “In situ” means it has remained in place and not grown into the rest of the breast.

Inflammatory breast cancer is a rare, aggressive form of cancer that affects the skin of the breast. Cancer cells block the skin’s lymph vessels, leading to pain, swelling, and redness of the breast.

Invasive ductal carcinoma is the most common form of breast cancer. Your doctor will suggest treatment based on whether the cancer cells contain hormone receptors or high levels of the HER2 protein.

When breast cancer cells spread (metastasize) from their original site, that is known as metastatic breast cancer. The most common organs for stage IV breast cancer to spread to are the bones, brain, liver, or lungs.

Triple-negative breast cancer is an aggressive cancer in which the cancer cells test negative for estrogen receptors, progesterone receptors, or HER2 protein. The lack of these three “targets” makes triple-negative breast cancer challenging to treat.

Breast reconstruction is surgery to create a new breast shape in place of a breast that has been removed (mastectomy). Your doctor will discuss timing and how reconstruction might fit into your overall treatment plan.

Medical oncologists treat cancer using medication, including chemotherapy, immunotherapy, and targeted therapy. Many breast cancer patients need some form of chemotherapy, or other drug regimen, either before or after surgery.

Clinical trials are scientific studies in which new treatments are tested in patients to determine if they are safe and effective. Your doctor will let you know whether you are eligible for any clinical trials.

Radiation therapy is often used in breast cancer following surgery to prevent the tumor from recurring. Each radiation treatment plan is based on the patient’s specific diagnosis and anatomy.

A mastectomy is surgery to remove one or both breasts, usually following a breast cancer diagnosis. Lumpectomy, or partial mastectomy, may be an option.