Stage 0 breast cancer, or ductal carcinoma in situ (DCIS), is when there are abnormal cells in the lining of the milk ducts. But those cells have not spread beyond the wall of the duct to reach surrounding tissue, the bloodstream, or lymph nodes.

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

Stage 0 breast cancer vs. lobular carcinoma in situ

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 abnormal cells in the lobules, but they don’t spread beyond the 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.

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 the nearest lymph nodes (stage 1B).

As we explore stage 0 breast cancer, we’re talking about DCIS, not stage 1 invasive breast cancer or LCIS.

In 2019, there will be about 271,270 new cases of breast cancer in the United States.

DCIS represents about 20 percent of all new diagnoses.

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

The exact cause of Stage 0 breast cancer isn’t clear, but there are factors that can increase your risk, such as:

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

There are also some lifestyle risks factors, which can be modified to reduce your risk, including:

  • physical inactivity
  • being overweight after menopause
  • taking hormone replacement therapy or certain hormonal oral contraceptives
  • drinking alcohol
  • smoking

See 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 other imaging test, such as an ultrasound.

If there’s still some question about the suspicious area, you’ll need a biopsy. 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 abnormal cells present and, if so, how aggressive they may be.

Mastectomy, or the removal of your breast, was once the standard treatment for stage 0 breast cancer, but it’s not always necessary today.

Some of the reasons to consider mastectomy are:

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

While mastectomy removes the 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 the breast and you may not need reconstruction surgery.

Radiation therapy uses high-energy beams to destroy any abnormal 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 five 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 to your doctor about the benefits and risks of each type of treatment.

Will I need chemo?

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

When you learn you have stage 0 breast cancer, you have some big decisions to make. It’s important to talk to 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 anxious, stressed, or having trouble coping with diagnosis and treatment, talk to your doctor. They can refer you toward 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.

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 mortality rate at 1.1 percent and the 20-year rate at 3.3 percent.

For women who had DCIS, the risk of dying from breast cancer was increased by 1.8 times over women in the general population. Death rates were higher for women diagnosed before age 35 than for older women, as well as for African-Americans over Caucasians.

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