Cancer occurs when cells multiply and grow out of control. If you have breast cancer, it means that this process began in your breast. No matter where those cells spread in your body, it’s still considered breast cancer.

Breast cancer can start in the milk-producing glands called lobules or in the ducts. It can also start in the body’s tissues. Increased blood flow or a buildup of white blood cells may occur. This can result in redness, warmth, or swelling, and it’s known as inflammatory breast cancer. When cells grow and divide uncontrollably, they form tumors. As the disease progresses, the cells begin to invade nearby tissue.

Eventually, cancerous cells can break away and travel to nearby lymph nodes. Once they’re in the lymphatic system, they can travel to distant organs like your bones or liver.

Staging is based on how big the original tumor is, how many lymph nodes are found to have cancer cells, and what, if any, other organs the cancer has spread to. The spread of cancer cells to other parts of the body is called metastasis.

If you have stage 3 breast cancer, it means your cancer has spread beyond your breast, but it hasn’t reached your distant organs. Stage 3 breaks down as follows:

Stage 3A

In stage 3A breast cancer, one of the following applies:

  • No tumor is in the breast or the tumor of the breast is any size. Cancer is found in four to nine nearby lymph nodes.
  • The tumor is larger than 5 centimeters. Small clusters of cancer cells are also found in nearby lymph nodes.
  • The tumor is larger than 5 centimeters. Cancer is also found in up to three nearby lymph nodes under your arm or near your breastbone.

Stage 3B

In stage 3B breast cancer, a tumor of any size is found. Cancer cells are found in the chest wall or skin of the breast. These areas may appear inflamed or have ulcers. In addition, one of the following applies:

  • Up to nine nearby lymph nodes are involved.
  • The cancer has spread to the lymph nodes near the breastbone.

Stage 3C

There could be a tumor of any size or no tumor at all. In addition, cancer has invaded the chest wall or skin of the breast. There’s inflammation or ulcers of the skin. In addition, one of the following applies:

  • Cancer is found in 10 or more of the underarm lymph nodes.
  • Cancer is found in the lymph nodes reaching up to the collarbone.
  • Cancer is found in the lymph nodes under the arm and near the breastbone.

Because stage 3 breast cancer has spread outside the breast, it’s harder to treat than early stage breast cancer. With aggressive treatment, stage 3 breast cancer is curable, but the risk that the cancer will grow back after treatment is high.

Staging is important, but there are other details about your cancer that you should also know about. These details will affect your treatment plan and individual outlook.

In addition to cancer stage, the pathologist will determine the tumor grade and tumor subtype. Tumors are graded on a scale of 1 to 3, based on how abnormal the cells appear compared to normal cells. The higher the grade, the more aggressive the cancer, meaning that it tends to be growing quickly.

The subtype is important because your treatment and outlook will vary depending on which subtype of breast cancer that you have.

It’s natural to want to know your outlook, but statistics don’t tell the whole story.

Survival rates can be confusing and don’t reflect your individual picture. The relative five-year survival rate for stage 3 breast cancer is 72 percent. This means that out of 100 people with stage 3 breast cancer, 72 will survive for five years. This figure doesn’t take breast cancer characteristics into account like grade or subtype. It also doesn’t separate people with stage 3A, 3B, and 3C.

In comparison, the five-year relative survival rate for both stage 0 and stage 1 breast cancer is 100 percent. For stage 2 breast cancer, it’s 93 percent, and for stage 4, it’s 22 percent. Based on these statistics, you can see that the earlier stage at diagnosis, the better your outlook.

The best source of information about your individual outlook is your own oncology team. Make sure you understand your breast cancer stage and subtype so that you can better understand your treatment and individual outlook. The most important thing is to get the right treatment and the support you need. This can help you to navigate the challenges of being diagnosed with stage 3 breast cancer.

Support groups can be a great source of comfort as you navigate your diagnosis through your treatment and beyond. Your doctor’s office or hospital can offer some suggestions and resources in your area.