Stage 0 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

When a patient is diagnosed with breast cancer, he or she may be given information about the cancer’s stage. The earliest stage is known as Stage 0 breast cancer. This is also called carcinoma in situ.

This guide to Stage 0 breast cancer is designed to help patients and their families learn more.

What Is Stage 0 Breast Cancer?

Stage 0 breast cancer is the earliest stage of breast cancer. In Stage 0, a grouping of abnormal cells is found within the breast, but the cells are noninvasive. This means they have not spread into nearby tissue.

Carcinoma in situ accounts for an estimated 20% of all new breast cancer cases, according to the American Cancer Society.

Stage 0 breast cancer may occur in two forms:

• Ductal carcinoma in situ (DCIS), in which abnormal cells are found in the lining of the breast ducts
• Paget’s disease of the breast, where abnormal cells develop on the areola or nipple skin (cancer cells may also be found in the breast ducts, but are not invasive at this lowest stage)

Is Stage 0 Breast Cancer Considered Cancer?

Stage 0 breast cancer is considered a noninvasive type of breast cancer. A preinvasive, or noninvasive, cancer type is one that has not spread into nearby breast tissue. This means the cancer cells have not metastasized, or spread, into other areas of the breast or body.

However, it is possible for a carcinoma in situ to become an invasive cancer. To reduce a patient’s risk, doctors may recommend treatment for Stage 0 cancers.

Stage 0 Breast Cancer Symptoms

Breast cancers may not always cause noticeable symptoms, especially in earlier stages. This is also true for Stage 0.

Stage 0 breast cancers usually do not have any symptoms. Instead, they are more often found during mammograms, the most widely used screening tool for breast cancer.

Diagnosing Carcinoma in Situ

A range of diagnostic tools may be used to help doctors diagnose carcinoma in situ. These include the following.

Mammogram: This is a commonly used imaging test used to diagnose breast cancer. A mammogram is a device that takes X-ray images of the breast. It is used for both screening and diagnostic purposes.

However, in some cases, other imaging tests may also be used, including magnetic resonance imaging (breast MRI) and breast ultrasound.

Breast biopsy: Guided by imaging tests, a core needle biopsy may be used to remove a cell sample from the breast. This procedure uses local anesthetic and a long, hollow needle to quickly remove several tissue samples, which are then examined under a microscope.

A biopsy is used for diagnosis but may also help doctors determine a cancer’s genetic makeup, which may assist with determining treatment options.

Stage 0 Breast Cancer Treatment

If a patient is diagnosed with breast carcinoma in situ, the care team will discuss current treatment options.

The most commonly employed treatments for Stage 0 breast cancer include the following.

Breast-conserving surgery (BCS): This is a surgical procedure to remove the cancer and some nearby tissue from the breast. This differs from a mastectomy in that the breast remains intact.

Mastectomy: This is the surgical removal of one or both breasts. If the Stage 0 cancer is large, or located in multiple areas, this option may be used. If the patient prefers, complete breast reconstruction may be performed as part of the surgical process.

Radiation therapy for breast cancer: High doses of targeted radiation are used to destroy cancer cells. This may be used following breast-conserving surgery, as it reduces the chance of the cancer returning.

Hormone therapy for breast cancer: Depending on the cancer’s genetic type, hormone therapy may be administered for several years after surgery to reduce recurrence. Hormone therapy may assist in destroying cancer cells by stopping the production of hormones that fuel their growth.

Stage 0 Breast Cancer Survival Rate

Survival rates for cancer are often measured in five-year periods. They are based on the percentage of patients who were still alive five years or more after their original breast cancer diagnosis.

For breast cancers (including Stage 0) that are localized, or contained to only one area, the five-year relative survival rate is 99.6%, according to the National Cancer Institute.

When breast cancers are detected in their early stages, this tends to correlate with increased survival rates.

Survival rates for advanced stage breast cancers continue to improve over time, as new breast cancer treatments are regularly emerging. Patients should speak with their care team for more information specific to their breast health.