When an individual is diagnosed with cancer, one of the first questions often asked concerns the stage of the disease. Stage 1 represents the earliest and most treatable form, while stage 4 is the most advanced and challenging to treat, as it indicates the cancer has spread to other parts of the body.

However, there is an even earlier classification known as stage 0 breast cancer. This stage is considered non-invasive, meaning that while abnormal cells with cancer-like characteristics are present within the milk ducts of the breast tissue, they have not yet spread to surrounding healthy tissue.

The encouraging news about stage 0 breast cancer is that it is highly treatable. When detected early, individuals can take proactive steps to prevent further progression. Although stage 0 breast cancer typically grows very slowly and may never advance to an invasive form, it should not be ignored. Detecting and addressing any form of cancer early — before it has the opportunity to grow or spread — is critical to achieving the best possible outcomes.

DCIS vs. LCIS: Types of Stage 0 Breast Cancer

The most common form of stage 0 breast cancer is ductal carcinoma in situ (DCIS). This condition occurs when abnormal cells are found in the tissue lining the milk ducts — the channels through which milk flows during breastfeeding. Paget’s disease, a rare condition in which abnormal cells appear in or around the nipple and areola, is also classified as a form of DCIS.

Lobular carcinoma in situ (LCIS), once considered stage 0 breast cancer, is now categorized as a precancerous condition rather than a direct precursor to invasive breast cancer. LCIS develops when abnormal cells form within the breast lobules, the glands responsible for producing milk.

Although both DCIS and LCIS contain the term carcinoma in their names, they are noninvasive, highly treatable, and not life-threatening. According to the American Cancer Society, the five-year survival rate for these conditions is nearly 100%.

However, if left untreated, abnormal cellular changes may continue, increasing the risk of developing invasive breast cancer in the future. For this reason, regular monitoring and appropriate treatment are typically recommended.

Symptoms of DCIS and LCIS

Ductal carcinoma in situ (DCIS) and lobular carcinoma in situ (LCIS) typically do not present noticeable symptoms. Although some individuals may experience a small, hard lump or nipple discharge, these conditions are most often detected during routine mammograms, which can reveal abnormal cellular changes before any symptoms develop.

In certain cases, LCIS may not appear on a mammogram and is instead discovered incidentally during a biopsy or diagnostic test performed for another breast abnormality.

However, Paget’s disease, a rare form of DCIS that affects the nipple and areola, can produce visible and physical symptoms, such as:

• Burning or itching around the nipple or areola
• Red, crusty, or scaly skin surrounding the nipple and areola
• Yellow or bloody nipple discharge
• A flat or inverted nipple

Treatment of DCIS and LCIS

Because it is not possible to predict whether stage 0 breast cancer will progress and invade surrounding tissues, ongoing monitoring and/or treatment are essential to reduce the risk of developing invasive breast cancer.

Several factors influence the appropriate treatment plan, including the patient’s age, family history, and the size or extent of the tumor. After a diagnosis of stage 0 breast cancer, the patient and healthcare provider work together to determine the most suitable course of action.

A lumpectomy — the surgical removal of abnormal cells and surrounding tissue while preserving most of the breast — is a common treatment for ductal carcinoma in situ (DCIS). In many cases, this procedure is followed by radiation therapy to eliminate any remaining abnormal cells. Because stage 0 breast cancer has not spread beyond the breast, chemotherapy is rarely required.

In some cases, a mastectomy, or surgical removal of the entire breast, may be recommended. This option is typically considered when the DCIS tumor is large, when multiple separate areas of DCIS are present in the same breast, or when the individual has a high risk of developing breast cancer.

If the DCIS is hormone-receptor positive, physicians may prescribe hormone-blocking medications, usually taken for about five years, to help prevent abnormal cells from returning. These hormonal therapy drugs can reduce the likelihood of cancer development since DCIS often depends on hormones like estrogen or progesterone to grow.

In contrast, lobular carcinoma in situ (LCIS) generally does not require immediate treatment. Instead, it is managed through careful monitoring or active surveillance, which includes regular mammograms and imaging tests such as breast MRI or ultrasound to detect any changes that could indicate the development of invasive cancer.

Can Stage 0 Breast Cancer Be Prevented?

Early detection remains the most effective defense against the development and progression of breast cancer. Mammograms and clinical breast examinations enable healthcare providers to identify and treat stage 0 breast cancer before it advances to a more serious stage.

Individuals in their 20s or 30s are encouraged to receive a clinical breast exam annually from a primary care provider or gynecologist. Those aged 40 and older should discuss their personal risk factors with their healthcare provider to determine how often they should undergo screening mammograms.

Understanding one’s family history is also essential, as it allows individuals to take preventive measures, such as early screenings and lifestyle adjustments to reduce risk. Maintaining a healthy lifestyle can further lower the likelihood of developing breast cancer. Key recommendations include:

• Eating a healthy, balanced diet
• Exercising regularly
• Limiting alcohol consumption
• Avoiding smoking
• Maintaining a healthy weight

Anyone who notices changes in their breasts should promptly consult a healthcare provider to determine the appropriate next steps.

For those diagnosed with stage 0 breast cancer, early detection represents the best possible scenario. By working closely with their provider, patients can create a personalized treatment plan and move forward with confidence, knowing that DCIS and LCIS generally have excellent prognoses.

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Dr. Erin Miller is a board-certified general surgeon.