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 surrounding tissue, your bloodstream, or lymph nodes.

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

Stage 0 vs. stage 1 breast cancer

In stage 1 breast cancer, the cancer is invasive, though it’s small and contained to breast tissue (stage 1A), or a small amount of cancer cells are found in your nearest lymph nodes (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).

How common is it?

In 2021, there will be about 281,550 new cases of breast cancer in the United States.

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

Stage 0 breast cancer used to include lobular carcinoma in situ (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, so follow-up is important.

Mastectomy, or the removal of your breast, was once the standard treatment for stage 0 breast cancer, according to a 2017 research review. But it’s not always necessary today.

Some of the reasons to consider mastectomy are:

  • you have DCIS in more than one part of your breast
  • the area is large relative to your breast size
  • you can’t have radiation therapy
  • you prefer mastectomy instead of a lumpectomy with radiation therapy

While mastectomy removes your entire breast, lumpectomy removes only the area of DCIS plus a small margin around it. Lumpectomy is also called breast-conserving surgery or wide local excision. This preserves most of your breast and you may not need reconstruction surgery.

Radiation therapy uses high energy beams to destroy any atypical cells that may have been left behind after surgery. Radiation therapy for stage 0 breast cancer may follow a lumpectomy or mastectomy. Treatments are given 5 days a week for several weeks.

If the DCIS is hormone receptor-positive (HR+), hormone therapy can be used to lower the chances of developing invasive breast cancer later.

Each case is different, so talk with your doctor about the benefits and risks of each type of treatment.

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 never having been pregnant
  • their first period before 12 years old or starting menopause after 55 years old

There are also some lifestyle factors, which can be modified to reduce your chances of developing the condition, including:

  • experiencing physical inactivity
  • having a larger body size after menopause
  • taking hormone replacement therapy or certain hormonal oral contraceptives
  • misusing alcohol
  • smoking

Contact your physician 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 say whether there are atypical cells 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 take the time to 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.

Here are some other things to consider:

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 American Cancer Society, women who’ve had DCIS are approximately 10 times more likely to develop invasive breast cancer than women who’ve never had DCIS.

In 2015, an observational study looked at more than 100,000 women who had been diagnosed with stage 0 breast cancer. The researchers estimated the 10-year breast cancer-specific negative outlook at 1.1 percent and the 20-year negative outlook at 3.3 percent.

For women who had DCIS, the chance of dying from breast cancer was increased by 1.8 times more than women in the general population. Negative outlooks were higher for women diagnosed before age 35 than for older women, as well as for African Americans compared to participants who were white.

It’s important to note that the stress of enduring racism, discrimination, and racist systems may have played a part in these inequities in healthcare for the research above.

For all these reasons, your doctor may recommend screening more frequently than if you never had DCIS.

Stage 0 breast cancer is considered noninvasive, but that doesn’t mean it should be ignored. 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.