Is DCIS Cancer or Not? Low Grade, Pre-Cancer, Symptoms, Causes

Medically Reviewed on 3/15/2022
ductal carcinoma in situ (DCIS)
Some doctors believe low-risk DCIS shouldn’t be referred to as "cancer," whereas others believe the cells constitute an early-stage malignancy.

The presence of abnormal cells confined to the milk ducts in the breast is referred to as ductal carcinoma in situ (DCIS). Some doctors believe that low-risk DCIS should not be referred to as "cancer," whereas others believe the cells constitute a true early-stage malignancy.

DCIS cells contain characteristics similar to cancer (carcinoma) cells. The cancer cells, however, remain contained ("in situ") and have not spread outside the milk ducts. This is one of the reasons there is so much controversy over DCIS.

  • DCIS is noninvasive, which means it has not spread outside of the milk duct and is quite unlikely to become invasive.
  • DCIS may never present a problem in some patients, but it may become invasive in others.
  • DCIS has typically been thought of as a precursor lesion to invasive breast cancer by some doctors.
  • DCIS accounts for roughly 20 percent of newly diagnosed cancer cases.
  • While DCIS is not an emergency, it does necessitate an assessment and discussion of treatment options.

What are the signs and symptoms of ductal carcinoma in situ?

More than 80 percent of DCIS instances are usually discovered during annual mammography, with or without symptoms. Symptoms when present may include a lump in the breast or unusual discharge from the nipple.

The number of women diagnosed with DCIS is increasing because women are getting frequent mammograms. DCIS is typically seen on a mammogram as little clusters of calcifications (white specks) with uneven forms and sizes.

What are the causes of ductal carcinoma in situ?

It is unknown what causes DCIS; however, it develops when genetic changes in the DNA of breast duct cells arise. Although the genetic alterations lead the cells to appear aberrant, the cells cannot yet break free from the breast duct.

Researchers are not sure what causes the aberrant cell development that leads to DCIS. A variety of factors, including genes passed down from parents, environment, and lifestyle, are likely to play a role.

13 factors that may increase your risk of DCIS

Thirteen risk factors for ductal carcinoma in situ (DCIS) include:

  1. Female gender
  2. Increasing age
  3. Personal history of breast diseases
  4. Family history of breast cancer
  5. First pregnancy after the age of 30 years
  6. Previous history of ductal carcinoma in situ (DCIS)
  7. Hormone replacement therapy
  8. Early menarche (getting the first period before age of 12 years)
  9. Late menopause (after the age of 55 years)
  10. High-fat diet
  11. Genetic mutations increase the risk of breast cancer (BRCA1 and BRCA2)
  12. Obesity
  13. Exposure to radiation either due to medical or environmental factors

Although studies have been conducted to analyze predictive markers to classify the invasive potential of DCIS, there is still a lack of standardization in the workup and treatment. Ongoing research may help anticipate which patients should be treated aggressively in the future.

DCIS affects around 50,000 women in the United States each year, making it one of the most frequent breast disorders. The good news is that these cells are contained within the ducts (in situ) and have not migrated to other organs. However, if left untreated, DCIS has the potential to progress to aggressive malignancy.


A lump in the breast is almost always cancer. See Answer

How is DCIS graded?

Ductal carcinoma in situ (DCIS) can be categorized based on its grade. The lower the grade, the more they look like normal breast cells. Lower grades likewise grow at a slower rate. Sometimes the cells are a mix of grades, which are referred to as "borderline" cells.


  • Grade I, low-grade or nuclear grade I: Under a microscope, the cancer cells resemble normal breast cells.
  • Grade II, moderate-grade, or nuclear grade II: These cells proliferate quicker than normal breast cells and resemble them less.
  • Grade III, high-grade or nuclear grade III:
    • These cells grow faster and have a very different appearance than regular breast cells.
    • People who have high-grade malignancies are more likely to develop invasive breast cancer in the future or have their present disease recur the following therapy.


DCIS cells are further classified into subgroups based on their pattern or shape when viewed under a microscope. Many tumors will have a combination of two or more subtypes.

  • Low or moderate grade:
    • Papillary: Finger-like projections cancer cells in the duct.
    • Micropapillary: Small, papillary cancer cells.
    • Cribriform: There are spaces or gaps between the cancer cells in the duct.
    • Solid: There is a dense cluster of cancer cells with no gaps between them.
  • High-grade:
    • Comedo: There is a dense collection of cancer cells, with a dead cell region in the center (also called necrotic). The cancer cells multiply rapidly within the duct, and some cells within the tumor lose their blood supply, resulting in necrosis.

If a questionable area is discovered on standard mammography, the radiologist will propose a diagnostic mammogram to take a deeper look. A breast tissue biopsy may be planned. A small sample of breast tissue is taken using core needle biopsy to diagnose ductal carcinoma in situ.

A pathologist will carefully examine the tissue under a microscope to determine the location of the tumor cells within the breast. To make a DCIS diagnosis, all the tumor cells must be found inside the ducts. This is significant because if tumor cells are discovered outside of the ducts, the diagnosis is changed to invasive ductal carcinoma.

4 treatment options for DCIS

Ductal carcinoma in situ (DCIS) has the potential to develop into aggressive cancer that spreads to other parts of the body. Once it has expanded outside the duct and into adjacent tissue, it can travel to other places of the body (metastasize) and become more difficult to cure.

Because there is no way to predict whether DCIS will progress to aggressive malignancy, practically all occurrences of DCIS are treated.

DCIS treatment methods include:

  1. Lumpectomy, with or without radiation therapy
    • The most prevalent kind of DCIS treatment.
    • A lumpectomy (also called breast-conserving surgery) involves the excision of only the breast mass or tumor and not the entire breast.
    • The lump is removed, along with a small amount of normal breast tissue surrounding it.
    • You may require radiation therapy following this procedure. Radiation therapy is the use of high-energy X-rays to destroy cancer cells.
  2. Simple mastectomy
    • The entire breast is removed with a standard mastectomy. The nipple, skin, areola, and breast tissue are included.
    • This may be necessary if the DCIS area is large, if there are multiple ducts with cancer cells or if cancer cells remain in the breast after a lumpectomy.
  3. Sentinel lymph node biopsy
    • During a lumpectomy or mastectomy, your doctor may want to check your lymph nodes.
    • The surgeon injects dye, which is picked up by the lymphatic system and transported to neighboring lymph nodes. The surgeon makes an incision and locates the lymph nodes that have dye in them.
    • The sentinel lymph nodes are the nodes that pick up the dye. They are extracted and examined for cancer cells.
  4. Hormone therapy
    • If a biopsy reveals that your DCIS is hormone-receptor-positive, you may be prescribed tamoxifen or an aromatase inhibitor.
    • Regardless of the type of medication used, it is common to take it for five years after a lumpectomy or mastectomy to reduce the risk of cancer returning or creating new cancer.

Some argue that ductal carcinoma in situ (DCIS) should not even be considered cancer because it is safe if it remains restricted to the milk duct. DCIS cells are "real cancer cells," yet the diagnosis should not paralyze people.

Doctors formally refer to DCIS as stage 0 breast cancer. Hence, with proper treatment, care, and diet, it has fewer chances of becoming invasive.

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Medically Reviewed on 3/15/2022
Image Source: iStock Images

Johns Hopkins Medicine. Ductal Carcinoma in Situ (DCIS).

American Cancer Society. Ductal Carcinoma In Situ (DCIS).

van Seijen M, Lips EH, Thompson AM, et al. Ductal carcinoma in situ: to treat or not to treat, that is the question. Br J Cancer. 2019;121(4):285-292.

Collins LC, Laronga C, Wong JS. Ductal carcinoma in situ: Treatment and prognosis. UpToDate.

PLOS. Don’t Tell Me My DCIS Isn’t Cancer!