What is Stage Zero Breast Cancer?

While stage zero breast cancer is slow-growing and highly treatable, that doesn’t mean it should be ignored.

If you’re diagnosed with breast cancer, asking which stage would likely be one of your first questions. Staging describes how extensive cancer is, including the size of the tumor, and whether it’s spread to surrounding tissues and other parts of the body. Stage 1 is the earliest, most treatable stage of cancer, while stage 4 is the most advanced. In stage 4, cancer has spread to other organs, making it the most difficult to treat.

But have you ever heard of stage zero cancer?

“Stage zero breast cancers are often called pre-cancers,” says Erin Miller, DO, breast surgeon at Geisinger. “In stage zero breast cancer, there are abnormal cells with cancer characteristics in the breast tissue — either in the milk ducts or breast lobules — but the cells haven’t spread to healthy tissue.”

There are two types of stage zero breast cancer: ductal carcinoma in situ (DCIS) and lobular carcinoma in situ (LCIS). While their names include the word carcinoma, these aren’t truly breast cancer.

The most common form, DCIS is when abnormal cells are in tissues in the milk ducts, the tubes milk flows through while breastfeeding. Paget’s disease — a rare condition where abnormal cells are found in or around the nipple and areola — is also classified as DCIS.

In LCIS, abnormal cells develop in the breast lobules, the glands that produce milk.

DCIS and LCIS are noninvasive and highly treatable, and they aren’t life threatening. In fact, the five-year survival rate is nearly 100%, according to the American Cancer Society. However, left untreated, abnormal changes can continue, increasing a person’s risk for developing breast cancer later on.

The good news about stage zero breast cancer: If you can detect it, you can take steps to prevent further development. While stage zero breast cancer is very slow-growing and may never progress to invasive cancer, don’t ignore it. Catching any cancer early — before it has a chance to grow and spread — is key to improving outcomes.

What are stage 0 breast cancer symptoms?

DCIS and LCIS typically don’t have symptoms. While it’s possible to feel a small, hard lump or have nipple discharge, most people discover they have the condition through regular mammogram screenings.

“In some cases, LCIS isn’t detected on a mammogram, but instead is found after a biopsy or test is conducted for another abnormality,” says Dr. Miller.

However, Paget’s disease can cause noticeable symptoms, including:

Burning or itching around the nipple or areola
Red, crusty or scaly skin around the nipple and areola
Nipple discharge that is yellow or bloody
A flat or inverted nipple

How is stage zero breast cancer treated?

Because providers can’t predict whether stage zero breast cancer will invade the tissues surrounding it, ongoing monitoring and treatment is key to reducing the risk of developing breast cancer. Treatment options can include surgery, radiation and hormone therapies.

“There are many factors that will determine your treatment plan, such as your age, family history and size of the tumor,” says Dr. Miller. “If you’ve been diagnosed with stage zero breast cancer, you and your doctor will discuss treatment options to put together a plan that’s right for you.”

A common treatment for DCIS is a lumpectomy, where the abnormal cells and surrounding tissue are removed from the breast, but most of the breast is preserved.

In most cases, surgery is followed by radiation therapy to destroy any abnormal cells that may have been left behind. Since stage zero breast cancer has not spread to other parts of the body, chemotherapy is typically not necessary.

Another option is a mastectomy, where the entire breast is surgically removed. A mastectomy may be necessary if the DCIS tumor is very large or the breast has several separate areas of DCIS.

If the DCIS is found to be hormone-receptor positive, your doctor may also prescribe hormone-blocking medication, which is typically taken for five years, to prevent abnormal cells from growing again.

“Hormonal therapy medicines can help reduce the risk of breast cancer developing because DCIS is often hormone-receptor positive, which means that estrogen or progesterone can promote abnormal cell growth,” says Dr. Miller.

Unlike DCIS, LCIS doesn’t require treatment, but rather close monitoring to detect breast cancer through mammograms and other types of imaging tests, such as an MRI or ultrasound.

Can I prevent stage zero breast cancer?

Early detection is the most effective defense against developing breast cancer. Screenings, such as mammograms and clinical breast exams, are the best methods of detection, in most cases. They help providers find and treat DCIS and LCIS before they have a chance to progress.

If you’re in your 20s or 30s, start getting a clinical breast exam annually from your primary care provider or gynecologist. If you’re over 40, be sure to talk to your doctor about risk factors that determine how often you should have a screening mammogram.

Also helpful is knowing your family history so you can take preventive steps, such as early screenings and mammograms. You can lower your risk for breast cancer by following a healthy lifestyle, including:

Eating a healthy, balanced diet
Exercising regularly
Limiting alcohol
Not smoking
Maintaining a healthy weight

“Talk to your doctor if you notice any changes to your breasts to determine the next best steps,” says Dr. Miller. “If you’re diagnosed with stage zero breast cancer, know you're facing the best-case scenario by catching it early. You can work closely with your provider to develop a treatment plan and move forward knowing DCIS and LCIS have excellent prognoses.”