Understanding the Stages of Breast Cancer

A patient’s breast cancer stage plays a major role in how the breast cancer can be treated.

One of the first steps in determining a breast cancer patient’s treatment plan is to figure out whether the cancer has spread — and if so, how far. This process is called staging.

The five stages of breast cancer are numbered 0 through IV (or 0-4). The lower the stage, the easier the cancer will be to treat and overcome.

Maria Nelson, MD, a board-certified breast surgical oncologist at the USC Norris Comprehensive Cancer Center, part of Keck Medicine of USC, and chief of the division of breast, endocrine and soft tissue surgery at the Keck School of Medicine of USC, explains how each breast cancer stage is defined and what patients can expect.

Determining the stages

Doctors use guidelines from the American Joint Commission on Cancer (AJCC) TNM system, 8th edition, to figure out which stage a patient’s breast cancer is at.

T: Tumor size.
N: Nodal status (how many regional lymph nodes are involved).
M: Metastasis (whether the cancer has spread to a distant location in the body).

Stage 0 breast cancer

In Stage 0, the earliest stage, the cancer hasn’t spread beyond the milk ducts. It’s called ductal carcinoma in situ (DCIS). The survival rate is nearly 100% when treated properly.

Treatment for Stage 0 breast cancer typically involves:

• Surgically removing the affected area with either a lumpectomy (removing only the cancer with rim of normal tissue) or a mastectomy (removing the whole breast).
• A pill is sometimes used to prevent the cancer from coming back.
• Sometimes, radiation therapy.

Chemotherapy is not used for Stage 0 breast cancer.

Stage 1 breast cancer

When a woman is diagnosed with breast cancer, doctors will check the lymph nodes, which is the first place breast cancer will spread. If no cancer is found in the lymph nodes, the cancer is classified as Stage 1, subcategorized into Stage 1A and 1B based on size and whether limited nodal disease is present.

Stage 1 treatment options include:

• A lumpectomy (or mastectomy, if the patient chooses).
• Radiation therapy.
• Often, five years on an anti-estrogen pill to prevent recurrence.
• In selected cases, chemotherapy.

Stage 2 breast cancer

In Stage 2 breast cancer, the tumor is limited to a region of the breast but larger than Stage 1. There may be limited disease in the regional lymph nodes.

Stage 2 breast cancer treatment options are:

• A lumpectomy or a mastectomy, depending on breast size and extent of disease.
• Radiation therapy.
• In some cases, chemotherapy.

Stage 3 breast cancer

In Stage 3 breast cancer, the cancer has spread further into the breast, and it has likely spread to the regional lymph nodes.

Recommended treatments for Stage 3 breast cancer include:

• A mastectomy, though a lumpectomy may still be an option in some cases.
• Radiation therapy.
• Often chemotherapy (either pre-surgery or post-surgery).
• In some cases, immunotherapy (depending on predictive markers that a doctor will test the patient for).

A rare condition called inflammatory breast cancer most often shows up at Stage 3, making the breast appear swollen, with skin that’s red and warm. Inflammatory breast cancer spreads quickly, so it’s important to see a doctor right away once symptoms appear.

Stage 4 breast cancer

With Stage 4 breast cancer, the cancer has spread beyond the breast and regional lymph nodes — typically to the bone, liver, lung or brain.

Cancer is easier to treat before it spreads

Early detection is the key to survival. Be sure to get your yearly mammogram and speak to your doctor if you have risk factors that may warrant additional imaging and or screening.

If you think you might be at higher risk of breast cancer, talk to your doctor about whether genetic testing or more frequent screenings could be right for you.

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