• Stage 0 breast cancer is the earliest stage of breast cancer that can be detected.
• Treatment for stage 0 breast cancer can involve surgery, radiation, or hormone therapy.
• The prognosis for stage 0 breast cancer is typically favorable, with a five-year survival rate of 99 percent.

Stage 0 breast cancer is typically found during routine screening and represents 20 percent of all newly diagnosed breast cancers in the United States. When breast cancer is detected at this early stage, the chance of survival is much higher than if it is found at later stages.

The oncologist (a doctor who specializes in treating cancer) will determine the stage of the disease and use this information to recommend treatment options and forecast prognosis (outlook). This article will cover details about what stage 0 breast cancer is, the most common treatments recommended, and how to understand the prognosis.

What Is Stage 0 Breast Cancer?

Stage 0 breast cancer is the earliest stage of detectable disease. At this stage, the disease is usually called ductal carcinoma in situ (DCIS), which means cancer cells have formed in the lining of the milk ducts. In situ means “in the original place” — the cancer cells have not spread.

DCIS is noninvasive, so there is no evidence of abnormal cells breaking through to the breast tissue surrounding the milk ducts. Although noninvasive disease is considered highly treatable, there is a chance that DCIS can eventually become invasive breast cancer.

Stage 0 disease used to also include lobular carcinoma in situ (LCIS), which occurs when abnormal cells form in the lobules (glands that make milk). LCIS is no longer considered stage 0 because it is not truly cancer — the cells are actually precancerous. However, LCIS may put a person at a higher risk of developing breast cancer.

Treatments for Stage 0 Breast Cancer

At stage 0, the goal of treatment is to remove all the cancer cells to prevent a more invasive form of cancer from developing. Treatment options for stage 0 breast cancer typically include surgery to remove the breast tumor and possibly the surrounding tissue. The type of surgery performed will depend on the circumstances of your cancer and your personal preferences.

Radiation therapy and hormone therapy are also commonly used after surgery to prevent cancer progression. Chemotherapy is usually not necessary at this stage because the cancer is noninvasive.

Lumpectomy

In a lumpectomy, a surgeon removes the breast tumor and some of the surrounding breast tissue. Also called breast-conserving surgery, lumpectomy avoids removal of the entire breast and is often recommended if the breast tumor is small enough.

If there are signs that stage 0 breast cancer may be progressing to a more advanced stage, a doctor may recommend a sentinel lymph node biopsy to remove the surrounding lymph nodes.

Radiotherapy

Radiotherapy after breast-conserving surgery such as a lumpectomy is used to kill any cancer cells that may remain after the procedure. It is considered standard treatment to complete radiation therapy after surgically removing the tumor. However, the risk of side effects may outweigh the benefits in some people who are older or have significant health problems.

Mastectomy

You may be offered a choice between lumpectomy and mastectomy, which is the total removal of the breast. A doctor is more likely to recommend a mastectomy over a lumpectomy if DCIS is widespread, affecting multiple spots in the breast. Mastectomy can be followed by reconstructive surgery.

Read more about lumpectomy versus mastectomy.

Hormone Therapy

Hormone therapy for breast cancer can be effective if the tumor is hormone receptor-positive, meaning that the cancer cells contain either the estrogen or progesterone receptor. These hormone receptors are proteins that play a role in breast cancer progression.

Not everyone will qualify for hormone therapy. Your doctor will first need to confirm the hormone receptor status of the cancer, because people with hormone receptor-negative tumors will not benefit from this type of therapy. However, most breast cancers are hormone receptor-positive.

People with stage 0 tumors that are hormone receptor-positive are treated with hormonal therapy such as tamoxifen (sold under the brand names Nolvadex and Soltamox) or exemestane (Aromasin). These drugs aim to decrease the risk of recurrence, or the possibility of cancer after surgery.

Prognosis for Stage 0 Breast Cancer

Survival rates for breast cancer are determined based on whether the cancer is localized (affects only the breast), regional (has spread to nearby tissues), or distant (has spread throughout the body). Localized disease has a very favorable prognosis, with a five-year survival rate of at least 99 percent, according to the American Cancer Society. This means that, on average, people with stage 0 breast cancer are 99 percent as likely as people without breast cancer to live for five years or more after diagnosis.

Follow-Up Care

Your doctor will analyze the cancer cells removed during surgery in what is called a pathology report. This report will give you and your doctor more information about the next steps in your cancer treatment plan.

Your doctor will want to watch you closely after treatment to make sure the cancer does not come back. It’s important that people treated for stage 0 breast cancer maintain regular follow-up appointments with their health care provider.

You’ll also need routine screening to detect cancer. You should perform regular breast self-exams at home and have a mammogram every six to 12 months if you’ve had breast-conserving surgery. If you had a total mastectomy, you won’t need a mammogram on that breast.

If you are taking hormone therapies, you may be at increased risks of uterine cancer and decreased bone density. Regular pelvic exams and bone density tests will be done to monitor for those conditions.

Talk With Others Who Understand

MyBCTeam is the social network for people with breast cancer and their loved ones. On MyBCTeam, members come together to ask questions, give advice, and share their stories with others who understand life with breast cancer.

Do you still have questions about stage 0 breast cancer? Share your experiences in the comments below, or start a conversation by posting on MyBCTeam.