If you've been diagnosed with breast cancer, you’ll want to know what stage it is. The answers will help you and your doctors know more about what’s ahead and decide on your treatments.
Doctors have many ways to find out what stage of breast cancer you have. Clues come from physical exams, biopsies, X-rays, bone scans and other images, and blood tests. A doctor called a pathologist puts tissue samples from the breast and lymph nodes under the microscope to find out even more.
ased on these findings, doctors string together letters and numbers to assign a stage to every case of breast cancer. It may seem like a strange code, but it’s really just a way to pinpoint exactly what’s going on with your cancer. Think of it like this: The longer the list of letters and numbers, the more exact the diagnosis and the more precise the treatment plan.

Breast Cancer Stages

The stages are the number zero and the Roman numerals I, II, III, or IV (often followed by A, B, or C). In general, the higher the number, the more advanced the cancer. But there’s more to it than that.
Stage 0. The cancer has been diagnosed early. It started in the breastducts or milk glands and has stayed there. You’re likely to hear or see the words in situ, meaning “in the original place.”
Stage I. Starting at this level, breast cancer is called invasive, meaning it has broken free to attack healthy tissue.
Stage 1A means the cancer has spread into the fatty breast tissue. The tumor itself is no larger than a shelled peanut, or there may be no tumor
Stage IB means some cancer cells, but just tiny amounts, have been found in a few lymph nodes.
Stage II. The cancer has grown, spread, or both.
IIA means the tumor in the breast is still small, if there's one at all. There may be no cancer in the lymph nodes, or it may have spread to as many as three.

A stage IIB breast tumor is bigger -- it may be the size of a walnut or as big as a lime. It may or may not be in any lymph nodes.
Stage III. The cancer has not spread to bones or organs, but it’s considered advanced, and it’s harder to fight.
IIIA means the cancer has been found in up to nine of the lymph nodes that form a chain from your underarm to your collarbone. Or it has spread to or enlarged the lymph nodes deep in your breast. In some cases there is a large tumor in the breast, but other times there’s no tumor.
IIIB means the tumor has grown into the chest wall or skin around your breast, even if it hasn’t spread to the lymph nodes.
IIIC means cancer has been found in 10 or more lymph nodes, or has spread above or below your collarbone. It’s also IIIC if fewer lymph nodes outside the breast are affected but those inside it are enlarged or cancerous.
Stage IV. Breast cancer cells have spread far away from the breast and lymph nodes right around it. The most common sites are the bones, lungs, liver, and brain. This stage is described as “metastatic,” meaning it has spread beyond the region of the body where it was first found.

TNM System for Breast Cancer

Doctors also group cancers by the letters T, N, or M. Each of those letters tells you something about your cancer.
“T” stands for tumor, or the lump of cancer found in the breast itself. The higher the number assigned after it, the bigger or wider the mass.
“N” stands for nodes, as in lymph nodes. These small filters are found throughout the body, and they're especially dense in and around the breast. They're meant to catch cancer cells before they travel to other parts of the body. Here, too, a number (0-III) tells you whether the cancer has spread to lymph nodes near the breast and, if so, how many.
“M” stands for metastasis. The cancer has spread beyond the breast and lymph nodes.

5-Year Survival Rates

The 5-year survival rate shows how many people live for at least 5 years after being diagnosed with breast cancer. It's based on the stage at the time of diagnosis. This rate is only an estimate, and some people will live much longer. The lower the stage, the better the chances of living longer. Your doctor can help you understand survival rates and what they mean for you.
According to the National Cancer Institute, the 5-year survival rates for breast cancer are:
Stage 0: 100%
Stage I: 100%
Stage II: 93%
Stage III: 72%
Stage IV: 22%
A breast cancer diagnosis is a lot to take in. You’ll have questions. Tell your doctor when you don’t understand something. Let her know when you want more information.