Breast Cancer Stage I

Stage 1 breast cancer is the earliest stage of invasive breast cancer, where the tumor is small and contained within the breast or has spread only minimally to nearby lymph nodes. With treatment, people diagnosed at this stage typically have excellent chances of recovery.

Table of contents

• What is Stage 1 Breast Cancer?
• Stage 1A and Stage 1B
• Understanding the Staging Systems
• Treatment Options
• Survival and Outlook

What is Stage 1 Breast Cancer?

Stage 1 breast cancer means that the cancer is small and only in the breast tissue, or it might be found in lymph nodes (small glands that help fight infection) close to the breast. It is considered an early stage breast cancer.^[1]

At stage 1, the breast cancer has spread from its original location in the ducts (tubes that carry milk) or lobules (milk-producing glands) to the surrounding tissue. However, it is still contained in a relatively small area.^[2] The cancer is called invasive because it has broken through from where it started and moved into nearby breast tissue.^[3]

The stage of cancer helps your doctor decide the best treatment for you. The stage tells you how big the cancer is and how far it has spread.^[1]

Stage 1A and Stage 1B

Stage 1 breast cancer can be divided into two groups: stage 1A and stage 1B.^[1]

Stage 1A

Stage 1A means that the cancer is 2 centimeters or smaller and has not spread outside the breast. No cancer cells have been found in the lymph nodes or other parts of the body at this stage.^[1]

Stage 1B

Stage 1B means that a few breast cancer cells are found in the lymph nodes close to the breast. In this stage, either no cancer is found in the breast itself, or the breast cancer is 2 centimeters or smaller.^[1] The group of cancer cells in the lymph nodes are no larger than 2 millimeters in size, called micrometastases.^[7]

Understanding the Staging Systems

There are different systems used to stage breast cancer. Doctors may use the number staging system (stages 0 through 4) or the TNM staging system.^[1]

TNM stands for Tumor, Node, and Metastasis. This system describes the size of the tumor, whether there are cancer cells in nearby lymph nodes, and whether the cancer has spread to other parts of the body.^[1]

In the TNM system, the doctor gives each factor a number. A very small cancer that hasn’t spread might be T1 N0 M0. In this system, stage 1A breast cancer is the same as T1 N0 M0. Stage 1B can be T0 N1mi M0 or T1 N1mi M0.^[1]

The stage of your breast cancer is based on the size of the tumor and if it has spread to other areas. It is also based on the type of tumor cells, including information about genes and biomarkers (substances that can indicate disease).^[4] Staging for breast cancer also considers hormone receptor status (whether the cancer responds to hormones), HER2 status (a protein that affects cancer growth), and the grade (how different the cancer cells look from normal cells).^[7]

Staging for breast cancer is very complex, and many different factors are considered before doctors can confirm your final stage. Speak to your doctor or breast cancer nurse specialist if you have any questions about your staging.^[1]

Treatment Options

Surgery is the usual treatment for stage 1 breast cancer.^[1] The type of surgery and other treatments you receive will depend on several factors.

Surgery

There are different types of surgery you might have:^[1]

• Surgery to remove just the cancer and a border of normal breast tissue around it. This is called breast conserving surgery or a wide local excision, also known as a lumpectomy.
• Surgery to remove the whole breast, called a mastectomy. You can then choose to have a new breast made, called breast reconstruction.

Checking the Lymph Nodes

Before your surgery, you have an ultrasound scan to check the lymph nodes in the armpit to see if they contain cancer cells. If breast cancer spreads, it usually first spreads to the lymph nodes close to the breast.^[1]

During surgery, your doctor will also remove some lymph nodes to see if there is cancer in them. There are two types of lymph node surgery: sentinel lymph node biopsy (removing just a few key lymph nodes) and axillary lymph node dissection (removing more lymph nodes from under the arm). The type of lymph node surgery you have depends on the size and other characteristics of the cancer.^[6]

Treatments After Surgery

You may have other treatments after surgery.^[1] After lumpectomy, most people receive radiation therapy to the breast area. After mastectomy, some people may also receive radiation to the breast area.^[6]

Other treatments may include:^[1]

• Hormone therapy if the cancer is hormone receptor-positive. This treatment helps reduce the risk of the cancer coming back.
• Chemotherapy, which uses drugs to kill cancer cells. Depending on the features of the cancer, chemotherapy may be recommended for some people to reduce the risk of the cancer returning.^[6]
• Targeted cancer drugs for cancers that have certain characteristics, such as cancers that are HER2-positive.
• Drugs that strengthen the bones called bisphosphonates.

Your doctor will take many different factors into account when deciding which treatment is best for you. These include the type of cells the cancer started in, whether your cancer cells have receptors for particular cancer drugs, the grade of the cancer, whether you have had the menopause, and other health conditions you may have.^[1]

Survival and Outlook

With treatment, people with early breast cancer usually have a very good chance of survival.^[11] Stage 1 breast cancer is the earliest stage of invasive breast cancer, and if you are diagnosed at this stage, this means the tumor is less than 2 centimeters in size with no cancer cells found in lymph nodes or other parts of the body.^[3]

From 2015 to 2021, the 5-year relative survival for women diagnosed with breast cancer that had not spread beyond the breast was 100%. This means women diagnosed with breast cancer that had not spread beyond the breast were just as likely to live 5 years beyond diagnosis as women in the general population.^[11]

Your chances of survival go up to 99% if you have stage 1, or cancer that’s only in your breast and hasn’t spread.^[19] About 90% of all people diagnosed with breast cancer will live 5 years after treatment.^[19]

That said, it’s important to know that how cancer affects you depends on several factors. The type of cancer you have, along with your age, overall health, and other factors play a role. You should ask your doctor how these things might affect treatment success.^[19]