• Breast cancer is diagnosed at stage 3 when it’s locally advanced, meaning the tumor has begun spreading to nearby organs.
• Stage 3 breast cancer treatment often begins with chemotherapy, followed by surgery.
• Mastectomy may be recommended for most stage 3 cases, but sometimes a lumpectomy can be combined with other treatments instead.

During a breast cancer diagnosis, your doctor will determine the stage of your cancer. Stages of breast cancer range from 0 to 4, based on the size of the tumor and how far cancer has spread. (Stages are also sometimes rendered in Roman numerals, e.g., “stage III” instead of “stage 3.”) If your doctor determines you have stage 3 breast cancer, that indicates you have locally advanced breast cancer that has begun to affect the tissue surrounding the breast and the lymph nodes in your armpit.

Knowing the stage can help your oncologist predict your prognosis (estimated outlook) and, with your preferences in mind, recommend the best treatment plan.

How Is Breast Cancer Stage Determined?

Breast cancer is staged using the TNM staging system, in which “TNM” stands for “tumor, node, metastasis.” The system looks at the following:

• Tumor — How large is the primary tumor?
• Node — Are there cancer cells in nearby or distant lymph nodes?
• Metastasis — Has the cancer spread to other parts of the body?

A greater extent of cancer spread indicates a more advanced stage. Understanding the nature of the disease and determining the best treatment options also requires additional information, such as:

• Hormone receptor status — Does the cancer contain estrogen receptor (ER) or progesterone receptor (PR) proteins?
• Tumor grade — How do the abnormal cancer cells look compared with normal cells?
• Human epidermal growth factor receptor 2 (HER2) status — How high are HER2 protein levels?

What Is Stage 3 Breast Cancer?

Stage 3 breast cancer is a more advanced form of invasive breast cancer. Cancer cells have spread from the milk ducts into the nearby lymph nodes, the skin of the breast, or the chest wall (the protective structures around the lungs).

Stage 3 breast cancer has three substages: 3A, 3B, and 3C. These substages describe in more detail how cancer cells have spread.

Stage 3 breast cancer may further be classified into substages — 3A, 3B, and 3C — depending on the size of the tumor and the extent of the cancer spread. For instance, in stage 2 breast cancer, the tumor may be smaller and/or cancer cells haven’t spread as far compared to stage 3.

Stage 3A Breast Cancer

Stage 3A breast cancer describes the following situations:

• The doctor doesn’t find a tumor in the breast or, if there is a tumor, it may be of any size.
• Cancer is found in four to nine axillary lymph nodes (those in the armpit region) or in the lymph nodes closest to the breastbone.
• The tumor is larger than 5 centimeters, and the lymph nodes have small groups of breast cancer cells between 0.2 millimeters and 2 millimeters in size.
• The tumor is larger than 5 centimeters, and the cancer has spread to one to three axillary lymph nodes or to lymph nodes near the breastbone.

Stage 3B Breast Cancer

In stage 3B breast cancer, the cancer has spread to the chest wall, the skin of the breast (causing ulcers or swelling), or both. It may also have spread to lymph nodes by the breastbone or to nine or fewer axillary lymph nodes.

Stage 3C Breast Cancer

In stage 3C breast cancer, it’s possible to have no signs of cancer in the breast. If a tumor is present, it may be any size and may have spread to the skin on the breast or the chest wall. Additionally, the cancer must have spread to one or more of the following areas:

• At least 10 axillary lymph nodes
• Lymph nodes below or above the collarbone
• Lymph nodes near the breastbone or in the armpit region

When breast cancer has spread to more distant parts of the body, a process known as metastasis, it’s considered stage 4, or metastatic, breast cancer.

Inflammatory Breast Cancer

Inflammatory breast cancer is always staged 3B or higher. In inflammatory breast cancer, the cancer cells block lymph vessels in the skin of the breast, making the skin feel warm and changing its appearance. These symptoms can sometimes be confused with mastitis, a breast inflammation that causes discoloration and swelling.

Treatments for Stage 3 Breast Cancer

Stage 3 breast cancer treatment often starts with chemotherapy, followed by surgery. If your cancer cells have certain genetic mutations (variants) or proteins, targeted drugs may also be used.

Chemotherapy

Chemotherapy (chemo) is often the first approach for treating stage 3 breast cancer. Chemotherapy is usually administered as neoadjuvant therapy, meaning it’s given before surgery. Chemo is beneficial because it can:

• Shrink the tumor so that it’s easier to remove
• Test that a particular chemotherapy is effective
• Allow, in some cases, for a less extensive surgical procedure

Chemotherapy is often the first treatment recommended for stage 3 breast cancer. It may be followed by lumpectomy or mastectomy.

Mastectomy or Lumpectomy

A mastectomy, the removal of the breast tissue, is often recommended for treating stage 3 breast cancer. Alternatively, a lumpectomy — also known as breast-conserving surgery or partial mastectomy — may be offered to preserve the surrounding healthy tissue.

Many people with stage 3 breast cancer aren’t candidates for a lumpectomy and may be recommended for a mastectomy to prevent cancer from returning. However, if neoadjuvant chemotherapy can shrink the tumor enough, a lumpectomy may become a viable option.

Following surgery, some people may choose to have reconstructive surgery to restore the appearance of their breasts.

Radiation

Radiation therapy is often administered following an operation to eliminate any remaining breast cancer cells that treatment may have missed.

Lymph Node Dissection

Lymph nodes containing cancer cells must also be removed. An axillary lymph node dissection gets rid of the lymph nodes in the armpit and is usually performed at the same time as a mastectomy.

Hormonal Therapy

Some breast cancers have proteins called hormone receptors on the surface of their cells, with estrogen and progesterone receptors playing a role in breast cancer progression. Hormone receptor-positive stage 3 breast cancer can be treated with hormonal therapy drugs such as tamoxifen or exemestane (Aromasin), which target the hormone receptors.

Targeted Therapy and Immunotherapy

Targeted therapy and immunotherapy drugs work by stopping the function of a particular protein or group of proteins. This approach may be recommended to help reduce the risk of breast cancer recurring (returning). For instance, HER2 is present at high levels in some breast cancers and affects how the cancer grows.

Stage 3 breast cancer treatment options may be based on whether a hormone receptor, the HER2 protein, or a BRCA gene mutation is present on cancer cells. In stage 3 breast cancer, targeted therapy options may include:

• Abemaciclib (Verzenio)
• Ado-trastuzumab emtansine (Kadcyla)
• Neratinib (Nerlynx)
• Olaparib (Lynparza)
• Pertuzumab (Perjeta)
• Ribociclib (Kisqali)
• Trastuzumab (Herceptin)

Treating Triple-Negative Breast Cancer

If breast cancer cells are negative for ER, PR, and HER2, the cancer is called triple-negative breast cancer (TNBC). TNBC is difficult to treat effectively with standard treatments, so newer approaches such as immunotherapy may be used to improve outcomes.

Immunotherapy drugs interact with the immune system to help it recognize and fight cancer cells. Pembrolizumab (Keytruda) is an immunotherapy used alongside chemotherapy to treat triple-negative stage 3 breast cancer that has returned or spread after surgery.

Read about which types of breast cancer have the highest rates of recurrence.

Prognosis for Stage 3 Breast Cancer

Stage 3 breast cancer is an advanced-stage disease, so prompt treatment is crucial for improving the prognosis.

As many as 86 percent of people live at least five years after being diagnosed with stage 3 breast cancer. Prompt treatment is necessary to get the best outlook.

Overall, stage 3 breast cancer has a somewhat favorable prognosis, with a five-year relative survival rate as high as 86 percent, according to the National Cancer Institute. This means that after their diagnosis, people with this type of breast cancer are 86 percent as likely as those without cancer to live for at least five years. This rate can vary depending on the exact substage and type of breast cancer. For instance, inflammatory breast cancer has a markedly lower survival rate, closer to 50 percent.

Hormonal therapy and other targeted drugs have helped improve outcomes for cancers with specific genetic features. Some people may be encouraged to participate in clinical trials, which may provide access to new treatments. Your oncology team can help you identify any clinical trials that may be appropriate for you.

Talk With Others Who Understand

MyBCTeam is the social network for people with breast cancer and their loved ones. On MyBCTeam, more than 73,000 members come together to ask questions, give advice, and share their stories with others who understand life with breast cancer.

Have you or a loved one been diagnosed with stage 3 breast cancer? Share your experiences in the comments below, or start a conversation by posting on your Activities page.