Breast cancer usually doesn’t have any symptoms, but getting regular screenings can help catch an early diagnosis. While stage 0 breast cancer isn’t considered invasive, it may become invasive.

Stage 0 breast cancer, or ductal carcinoma in situ (DCIS), is when there are atypical cells in the lining of your milk ducts. But those cells have not spread beyond the wall of the duct to reach:

DCIS is noninvasive and is sometimes called “precancer.” However, DCIS has the potential to become invasive.

In stage 1 breast cancer, the cancer is invasive. If it’s small and contained to breast tissue, it’s considered stage 1A, and if a small amount of cancer cells are found in your nearest lymph nodes, it’s considered stage 1B.

As we explore stage 0 breast cancer, we’re talking about DCIS, not stage 1 invasive breast cancer or lobular carcinoma in situ (LCIS).

In 2023, there were an estimated 297,790 new cases of invasive breast cancer in women in the U.S. In 2024, this number increased to 310,720.

About 30 percent of newly diagnosed cancers in women every year are attributed to breast cancer.

DCIS represents about 20-25 percent of all new diagnoses, according to a 2018 research review.

Stage 0 breast cancer used to include LCIS. Even though the name contains the word carcinoma, LCIS is no longer categorized as cancer.

LCIS involves atypical cells in your lobules, but they don’t spread beyond your lobules.

LCIS is sometimes called “lobular neoplasia.” It doesn’t necessarily require treatment. However, LCIS can increase your risk of developing invasive cancer in the future, according to the American Cancer Society (ACS), so follow-up is important.

Which treatment you receive or your doctor recommends may depend on a few factors. Each case is different, so talk with your doctor about the benefits and risks of each type of treatment.

Mastectomy

Mastectomy is not always necessary today. But some of the reasons to consider mastectomy are:

Lumpectomy

While mastectomy removes your entire breast, lumpectomy removes only the area of DCIS plus a small margin of tissue around it.

Lumpectomy is also called breast-conserving surgery or wide local excision. This preserves most of your breast, and you may not need breast reconstruction surgery.

The outlook is the same for those who undergo mastectomy compared to those who undergo a lumpectomy followed by radiation.

Radiation therapy

Radiation therapy uses high-energy beams to destroy any atypical cells that may have been left behind after surgery. Most women typically do not need radiation following a mastectomy for DCIS, according to the ACS.

Radiation therapy for stage 0 breast cancer may follow a lumpectomy or mastectomy. It’s often recommended after a lumpectomy. Treatments are given 5 days a week for several weeks.

Hormone therapy

Hormone therapy can be used to lower the chances of developing another DCIS or developing invasive cancer in either breast when taken for 5 years after surgery.

If the DCIS is hormone receptor-positive (HR+), your doctor may recommend treatment with tamoxifen or aromatase inhibitors, such as exemestane or anastrozole. Which therapy your doctor recommends may depend on whether you are past menopause.

Hormone therapy may increase life expectancy following breast cancer diagnosis for women who took the hormonal therapy for 5–10 years. Keep in mind this refers to all breast cancers, not just DCIS.

Chemotherapy

Chemotherapy is used to shrink tumors and destroy cancer cells throughout your body. Since stage 0 breast cancer is noninvasive, this systemic treatment is generally not necessary.

There are generally no symptoms of stage 0 breast cancer, though it can occasionally cause a breast lump or bloody discharge from your nipple.

The exact cause of stage 0 breast cancer isn’t clear, but the condition can be more common in people who have:

  • increasing age
  • a personal history of atypical hyperplasia or other benign breast disease
  • a family history of breast cancer or genetic mutations that can increase the risk of breast cancer, such as BRCA1 or BRCA2
  • their first child after 30 years old or have never been pregnant
  • their first period before 12 years old or have started menopause after 55 years old

Some lifestyle factors can be modified to reduce your chances of developing the condition, including:

Contact your doctor if you have a lump or other changes to your breasts. Discuss your family history of cancer and ask how often you should be screened.

Stage 0 breast cancer is often found during mammogram screening. Following a suspicious mammogram, your doctor may order a diagnostic mammogram or another imaging test, such as an ultrasound.

If there’s still some question about the suspicious area, you’ll need a biopsy. Biopsy is the only way to diagnose cancer. For this, the doctor will use a needle to remove a tissue sample.

A pathologist will examine the tissue under a microscope and provide a report to your doctor. The pathology report will indicate whether atypical cells are present and, if so, how aggressive they may be.

When you learn you have stage 0 breast cancer, you have some big decisions to make.

It’s important to talk with your doctor about your diagnosis in depth. Ask for clarification if you don’t quite understand the diagnosis or your treatment options. You can also get a second opinion.

There’s a lot to think about. If you’re feeling anxious, stressed, or experiencing difficulty coping with the diagnosis and treatment, talk with your doctor. They can refer you to support services in your area.

You may also want to:

The ACS Support Programs and Services page provides information about resources, either online or in your area. You can also live chat with a representative or, if you’re in the U.S., call the helpline at 1-800-227-2345.

Strategies to ease stress and anxiety include:

Stage 0 breast cancer can be very slow-growing and may never progress to invasive cancer. It can be successfully treated.

According to the ACS, women who have had DCIS are approximately 10 times more likely to develop invasive breast cancer than women who’ve never had DCIS.

In 2020, a cohort study looked at more than 140,000 women who had been treated for DCIS. Researchers saw the chance of death from breast cancer increased three-fold after diagnosis of DCIS.

For all this reason, your doctor may recommend screening more frequently if you have or have had DCIS.

Stage 0 breast cancer is considered noninvasive, but that doesn’t mean it should be ignored. It has the potential to become invasive if left untreated.

Treatments can range from removal surgeries, such as a lumpectomy or mastectomy, to systemic therapies, such as radiation or hormonal. Your doctor will help you decide which treatment is best for you.

If you believe you feel a lump in your breast, talk with your doctor to determine the next best steps. They will help guide you through the diagnosis and treatment process.