Stage 1 Breast Cancer

April 10, 2025

This page was reviewed under our medical and editorial policy by Susan Yost, Ph.D., staff scientist, Department of Medical Oncology & Therapeutics Research, City of Hope^® Cancer Center Duarte

During a patient’s breast cancer diagnosis, their care team may also provide information about the cancer’s stage. Stage 1 breast cancer is early-stage disease.

This guide to Stage 1 breast cancer will help patients learn more.

What Is Stage 1 Breast Cancer?

Stage 1 is an early-stage invasive breast cancer. An invasive cancer is one that has spread outside the tissue where it began and into the surrounding healthy tissue.

However, in Stage 1, the tumor is very small and has not spread into distant areas of the body. In some cases, it may have spread into nearby lymph nodes.

Stage 1 breast cancer is divided into two subtypes, Stage 1a and Stage 1b.

Stage 1a Breast Cancer

A breast cancer is defined as Stage 1a if:

• The tumor is smaller than 20 mm in size
• The cancer has not spread into nearby lymph nodes or into any other areas of the body

Stage 1b Breast Cancer

Stage 1b breast cancers are diagnosed if:

• Cancer is undetectable in the breast but some cancer cells have been found in the lymph nodes closest to it
• Or the breast tumor is smaller than 20 mm in size, and some cancer cells have been found in lymph nodes nearest to the breast

In both types of 1b breast cancer, cancer cells have not spread to distant areas of the body.

Stage 1 Breast Cancer Symptoms

In Stage 1 and early stages of breast cancer, not all patients experience symptoms, although some will. A breast lump, or mass, is the most common one.

Other symptoms of breast cancer in its earlier stages may include:

• Skin changes to the breast, including swelling, skin thickening, dimpling or irritation
• Nipple discharge, other than breast milk
• Pain or discomfort
• Red or flaky skin on the breast or nipple
• The nipple starts to pull inward

Many of these symptoms may also be caused by conditions other than breast cancer, however.

Diagnosing Stage 1 Breast Cancer

If a doctor suspects a patient may have breast cancer, a number of diagnostic tests may be used. These tests assist with both breast cancer diagnosis and staging.

Mammogram: This test uses X-ray machines to obtain detailed images of the breast. It may be used for both breast cancer screening and diagnosis.

Breast biopsy: This is a diagnostic tool in which a tissue sample is removed from the breast and examined under a microscope to look for cancer cells. In some cases, tissue may also be taken from the nearby lymph nodes.

Biopsies may be performed in several ways, depending on a tumor’s size and location, and the patient’s health. Most commonly, a core needle biopsy is used for diagnosing breast cancer.

In a core needle biopsy, a large, hollow needle is used to remove a tissue sample from the breast. Before the biopsy begins, the patient receives a local anesthetic to prevent discomfort. An imaging test may be used to provide guidance.

Magnetic resonance imaging (breast MRI): A type of imaging test, MRI uses powerful magnets and radio waves to produce images of the breasts. An MRI may be used as a diagnostic tool, but it is also used to determine if breast cancer has spread.

Stage 1 Breast Cancer Treatment

If a patient is diagnosed with Stage 1 breast cancer, the care team will create a personalized treatment plan specific to his or her needs.

The most commonly used treatments for Stage 1 breast cancer include the following.

Breast cancer surgery: This is the most frequently used treatment for Stage 1 breast cancer. Depending on the cancer and the patient’s health and preferences, the surgery may be breast-conserving surgery (BCS), removing the tumor and some of the nearby tissue, or a mastectomy, completely removing one or both breasts. Breast reconstruction after surgery is also an option for patients.

In some patients, the nearby lymph nodes may also be surgically removed.

Radiation therapy for breast cancer: This treatment uses high-energy X-rays to destroy cancer cells. For Stage 1 patients, radiation therapy may be used after surgery to reduce the risk of recurrence.

Hormone therapy for breast cancer: Patients with hormone receptor-positive cancer types may receive medication designed to stop the growth of cancer cells fueled by certain hormones.

Chemotherapy for breast cancer: If a patient’s cancer is considered fast-growing or has genetic factors that increase the risk of spread, chemotherapy may be used to destroy cancer cells.

Stage 1 Breast Cancer Recurrence Rate

Sometimes, breast cancer comes back after the patient’s original treatment has finished. This is known as breast cancer recurrence.

For patients with early-stage breast cancer, recurrence rates are low compared to advanced-stage cancer, but research shows that it varies for each patient depending on tumor features and whether the tissue right outside the tumor (tumor margins) and/or lymph nodes have cancer cells.

In patients who have a lumpectomy plus radiation therapy, the recurrence rate may also vary based on which risk-lowering drug treatment options are followed after the primary treatments.

Patients may discuss the possibility of recurrence with their care team to find out more.

Stage 1 Breast Cancer Survival Rate

The five-year relative survival rate for breast cancer that is localized within the breast is 99.6%, according to the National Cancer Institute. If the cancer has spread into nearby areas, the five-year relative survival rate is 86.7%. These are estimates of how many patients are still alive at least five years after their initial diagnosis.

Every person’s health circumstance is unique, though, so patients may wish to talk to their care team for more specific information on their health.