Understanding Ductal Carcinoma In Situ (DCIS)

Learn more about DCIS and how BCRF is advancing research to understand and treat stage 0 breast cancer

Breast cancer is the most common cancer in women living in the U.S. Of all breast cancer diagnoses in the country, 20-25 percent are ductal carcinoma in situ (DCIS). An estimated 60,730 new cases of DCIS will be diagnosed in women in 2026.

Though it can be very stressful and alarming, DCIS is not life-threatening—practically all patients with stage 0 breast cancer can be cured.

What is ductal carcinoma in situ (DCIS)?

DCIS stands for ductal carcinoma in situ, a non-invasive breast cancer in which abnormal cells are found only inside the milk ducts. Ductal carcinoma in situ (DCIS) is the earliest stage of breast cancer, which is why it’s sometimes referred to as stage 0 breast cancer. DCIS, by definition, is cancer that starts in the cells lining the milk ducts (carcinoma) and remains in the area where it originates (in situ). DCIS remains in the milk duct and does not spread through the duct walls into the surrounding breast tissue. Stage 0 breast cancer is considered to be a precursor to invasive, stage 1–4 breast cancers.

Although DCIS is defined by the area in which it occurs, the lesions can significantly differ from patient to patient and can vary in molecular and histological features, genetics, clinical presentation, and potential to progress to invasive breast cancer. Ductal carcinoma in situ is classified into the same molecular subtypes as invasive breast cancer. More about DCIS classification is discussed with regard to DCIS diagnosis and DCIS treatment below.

DCIS vs. LCIS

Similar to ductal carcinoma in situ (DCIS), lobular carcinoma in situ begins—and remains—in the cells that line the breast lobules (the glands that make milk). While DCIS is the most common type of non-invasive breast cancer, accounting for 4-5% of all breast biopsies, LCIS is much rarer and accounts for approximately 0.5–4 percent of benign breast biopsies.

	DCIS	LCIS
Where it starts	Cells lining the milk ducts	Cells lining the lobules (milk-making glands)
How common	The most common non-invasive breast cancer	Much rarer, about 0.5–4 percent of benign breast biopsies
Precursor to invasive cancer?	Yes, considered a precursor to invasive ductal carcinoma (IDC)	Yes, considered a precursor to invasive lobular carcinoma (ILC)
Risk factor for invasive cancer?	Yes, considered a risk factor for IDC	Yes, considered a risk factor for both ILC and IDC
Also called	Stage 0 breast cancer, non-invasive breast cancer, ductal intraepithelial neoplasia	Lobular neoplasia, lobular intraepithelial neoplasia, atypical lobular hyperplasia
Typical management	Surgery, often with radiation and/or hormone therapy	Removal, followed by observation

Interestingly, unlike DCIS, researchers have observed that LCIS is not a precursor to invasive breast cancer. Rather, it’s considered a marker for increased breast cancer risk, much like family history. For this reason, some experts prefer the term “lobular neoplasia”—neoplasia meaning abnormal growth of cells that can be benign—instead of “lobular carcinoma.” After surgical removal of the lesion, LCIS patients typically undergo observation rather than further treatment.

DCIS symptoms

Most people will not experience any DCIS symptoms. In rare cases, women may feel a lump in their breast or have nipple discharge. But typically, ductal carcinoma in situ (DCIS) is found on a mammogram. Because DCIS rarely causes symptoms, it is typically found by regular screening. Any new lump, nipple discharge or other breast change should be checked by a doctor.

How is DCIS diagnosed?

DCIS diagnosis has increased significantly since routine screening mammograms became widespread. Before screening mammography, less than five percent of newly diagnosed breast cancers were DCIS, whereas now 20-25 percent of diagnosed breast cancers are DCIS. From 1973–1975, before routine mammography, the incidence of DCIS was 1.87 per 100,000 people screened. This rose dramatically to 32.5 by 2004 and has since plateaued.

When a radiologist reads a screening mammogram, they usually identify DCIS by the appearance of microcalcifications that are either localized or widespread and have irregular shapes and sizes. An additional diagnostic mammogram is usually recommended, which takes images at higher magnification from more angles. This mammogram evaluates both breasts and provides a closer look at the microcalcifications to determine whether they are a cause for concern. If the area in question needs further evaluation, additional imaging may be done followed by breast biopsy.

A DCIS diagnosis is ultimately confirmed by biopsy; tissue is removed and sent to the lab for analysis. DCIS can vary in its structural features and genetics, which adds complexity to diagnosis and has led to multiple systems for classification.

DCIS grade

Typically, DCIS is categorized by what’s called nuclear grade, which measures the characteristics of the nuclei of the cells like size and shape compared to the nuclei of normal breast cells. A DCIS diagnosis is categorized as low-grade (grade 1), intermediate grade (grade 2), or high-grade (grade 3). The higher the grade, the more abnormal the nuclei and the more aggressive and fast-growing the cancer cells. Grade also matters for treatment: the chance that an area of DCIS also contains invasive cancer increases with the size and grade of the DCIS.

Can DCIS be triple-negative?

Each of the molecular subtypes of invasive breast cancer can be identified in DCIS, but the prevalence of each is different. In particular, triple-negative and similar, basal-like subtypes are uncommon in DCIS. DCIS is a key intermediate in the progression to invasive breast cancer, but different subtypes grow at different rates, and not all breast cancers appear to have a long-lived DCIS stage—notably, triple-negative breast cancer. Research suggests that the rapid tumor progression that is a hallmark of triple-negative breast tumors means that there is seldom triple-negative DCIS at the time of diagnosis.

DCIS treatment

Having DCIS can increase one’s risk of developing invasive breast cancer. Currently, there is not a way to determine which DCIS cases will become invasive breast cancer and which will not, so DCIS is almost always treated.

DCIS treatment has a high success rate, in most cases removing the tumor and preventing recurrence. The prognosis is excellent—98 percent survival after 10 years.

Lumpectomy or mastectomy for DCIS?

For most people, stage 0 breast cancer is localized to a small area and DCIS treatment includes breast-conserving surgery (lumpectomy). If the DCIS is widespread relative to the area of the breast or is multifocal (occurring in more than one area of the breast), mastectomy is recommended, and no further treatment is needed in most cases.

A mastectomy may also be recommended if surgeons cannot remove the DCIS with clear margins, meaning a rim of healthy tissue around the removed area, even after a second surgery. Some people choose mastectomy because they cannot have radiation, or simply because they prefer it. Studies following thousands of women for more than 20 years show that survival after lumpectomy with radiation is the same as after mastectomy, so the decision often depends on how much of the breast is affected and on personal preference.

Radiation and hormone therapy

Lumpectomy is usually then followed by radiation therapy. Any remaining abnormal cells are killed with high-energy beams, such as X-ray or proton. Radiation therapy after lumpectomy reduces the chance that DCIS will recur or that it will progress to invasive cancer. Radiation following lumpectomy is not necessary in some instances, such as if the area of DCIS is small and low-grade.

Hormone therapy may be given after surgery or radiation in some cases of hormone receptor–positive DCIS to decrease the risk of future invasive breast cancer.

DCIS prognosis and survival rate

The long-term outlook for DCIS is excellent. In a study of more than 100,000 women diagnosed with DCIS, about 3 percent died of breast cancer within 20 years, a rate similar to that of women in the general population. The risk was higher for women diagnosed before age 35 and for Black women, at about 8 percent and 7 percent, respectively.

Is DCIS cancer? Should ductal carcinoma in situ be treated like invasive breast cancer?

DCIS is considered pre-invasive and an early form of breast cancer because the cells inside the duct are cancerous. However, DCIS treatment is controversial and remains a clinical challenge. If left untreated, some cases of DCIS will transform into invasive breast cancer, but it is uncertain how many. Estimates of DCIS cases that will become invasive breast cancer range from 20-50 percent. Put another way, 50-80 percent of DCIS cases will not become invasive.

Currently, our ability to stratify DCIS by risk is in its early stages. At this point, the standard of care is to reduce risk as much as possible by treating DCIS like early-stage breast cancer, typically with the combination of surgery, radiation, and hormone therapy depending on the case. These DCIS treatments are recommended because they have been shown in clinical trials to decrease the risk of developing an invasive breast cancer in the future; however, the 10-year survival rate for a DCIS diagnosis is very high (at 98 percent) regardless of whether treatment is given after surgery. Because DCIS treatment does not improve survival, researchers, clinicians, and others have raised concerns that DCIS may be overtreated and debated whether treatment benefits outweigh impacts on quality of life.

Clinicians and patients, then, face the dilemma of having to weigh these risks versus benefits. DCIS treatment can be costly and take a physical and emotional toll on a patient. At this time, it is not possible to predict which cases of DCIS will become invasive breast cancer and which will not, which is why research into DCIS is so needed.

BCRF research into ductal carcinoma in situ

BCRF is the largest private funder of breast cancer research in the world and is dedicated to improving our understanding of all stages of the disease. Compared to invasive breast cancer, DCIS has been understudied, resulting in uncertainties about the best ways to manage a stage 0 breast cancer/DCIS diagnosis.

BCRF investigators are working to understand how DCIS progresses to invasive disease, to predict which DCIS cases will become invasive breast cancer, and to improve DCIS treatment by:

• Conducting a clinical trial for low-risk DCIS comparing close monitoring (via screening) to standard-of-care treatment to find predictors of invasive disease
• Identifying biomarkers that predict low vs. high risk of DCIS progression to invasive breast cancer
• Studying the immune landscape of DCIS and how cancer cells escape surveillance to become invasive breast cancer
• Analyzing cells that line the milk ducts to understand their role in preventing immune cells from blocking DCIS
• Developing a method to determine how the age of DCIS lesions can be used to predict aggressiveness and inform treatment decisions

Early results from a large national trial called COMET were published in 2024. Among women with low-risk, hormone receptor-positive DCIS, those assigned to active monitoring (imaging and exams every six months) had a similar rate of invasive cancer after two years as those assigned to standard treatment with surgery. Longer follow-up is needed before active monitoring can become a standard option.

Through these investigations, BCRF researchers are hoping to gain new insights into stage 0 breast cancer and prevent overtreatment. Understanding the process by which DCIS becomes invasive breast cancer and uncovering predictors of progression are critical to improving DCIS treatment guidelines—and may even offer insights into breast cancer’s origins.

Improving care for people with DCIS

DCIS is highly treatable, and most people diagnosed with it go on to live long, healthy lives. The challenge now is learning which cases need treatment and which do not, so that every patient gets the care they need without the treatment they don’t.

Support the research driving these discoveries. Donate, start a fundraiser, or explore other ways to give and help fund the science that’s improving care for people with DCIS.

Frequently asked questions

What is the difference between DCIS and invasive ductal carcinoma?

Invasive ductal carcinoma (IDC) also begins in the milk ducts, but it has grown through the duct wall into the surrounding breast tissue. From there, it can spread to the lymph nodes and other parts of the body. DCIS stays inside the ducts. Some biopsies show both DCIS and IDC in the same area of the breast.

Can DCIS come back after treatment?

Yes. DCIS can come back in the same breast, either as DCIS or as invasive breast cancer. Radiation after lumpectomy lowers this risk, and hormone therapy may lower it further for hormone receptor-positive DCIS. People who have had DCIS also have a higher risk of a new breast cancer in either breast, so regular follow-up mammograms are important.

Will I need chemotherapy or lymph node surgery for DCIS?

Usually not. Because DCIS has not spread beyond the milk ducts, chemotherapy is generally not part of treatment. Lymph nodes usually do not need to be removed either, although a surgeon may check them during a mastectomy or if invasive cancer is found.

Selected references

American Cancer Society. (2026). Key statistics for breast cancer. https://www.cancer.org/cancer/types/breast-cancer/key-statistics.html

American Cancer Society. Treatment of ductal carcinoma in situ (DCIS). https://www.cancer.org/cancer/breast-cancer/treatment/treatment-of-breast-cancer-by-stage/treatment-of-ductal-carcinoma-in-situ-dcis.html

Bergholtz, H., Lien, T. G., Swanson, D. M., Frigessi, A., Daidone, M. G., Tost, J., … & Sørlie, T. (2020). Contrasting DCIS and invasive breast cancer by subtype suggests basal-like DCIS as distinct lesions. NPJ breast cancer, 6(1), 1-9.

DCIS, LCIS. (2019, December 5). Rogel Cancer Center. https://www.rogelcancercenter.org/living-with-cancer/treatment-choices/dcis-lcis-%E2%80%93-do-i-have-breast-cancer

Ductal Carcinoma in Situ (DCIS). (2021). American Cancer Society. https://www.cancer.org/cancer/breast-cancer/about/types-of-breast-cancer/dcis.html

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Hanna, W. M., Parra-Herran, C., Lu, F. I., Slodkowska, E., Rakovitch, E., & Nofech-Mozes, S. (2019). Ductal carcinoma in situ of the breast: an update for the pathologist in the era of individualized risk assessment and tailored therapies. Modern Pathology, 32(7), 896-915.

Hoffman, A. W., Ibarra-Drendall, C., Espina, V., Liotta, L., & Seewaldt, V. (2012). Ductal carcinoma in situ: challenges, opportunities, and uncharted waters. American Society of Clinical Oncology Educational Book, 32(1), 40-44.

Hwang, E. S., Hyslop, T., Lynch, T., et al. (2025). Active monitoring with or without endocrine therapy for low-risk ductal carcinoma in situ: The COMET randomized clinical trial. JAMA, 333(11), 972–980. https://doi.org/10.1001/jama.2024.26698

Kurbel, S. (2013). In search of triple-negative DCIS: tumor-type dependent model of breast cancer progression from DCIS to the invasive cancer. Tumor Biology, 34(1), 1-7.

Narod, S. A., Iqbal, J., Giannakeas, V., Sopik, V., & Sun, P. (2015). Breast cancer mortality after a diagnosis of ductal carcinoma in situ. JAMA Oncology, 1(7), 888–896. https://doi.org/10.1001/jamaoncol.2015.2510

Pinder, S. E. (2010). Ductal carcinoma in situ (DCIS): pathological features, differential diagnosis, prognostic factors and specimen evaluation. Modern Pathology, 23(2), S8-S13.

Tomlinson-Hansen, S., Khan, M., & Cassaro, S. (2022). Breast Ductal Carcinoma in Situ. StatPearls Publishing. https://www.ncbi.nlm.nih.gov/books/NBK567766

Virnig, B. A., Tuttle, T. M., Shamliyan, T., & Kane, R. L. (2010). Ductal carcinoma in situ of the breast: a systematic review of incidence, treatment, and outcomes. Journal of the National Cancer Institute, 102(3), 170-178.

Zhou, W., Jirström, K., Amini, R. M., Fjällskog, M. L., Sollie, T., Lindman, H., … & Wärnberg, F. (2013). Molecular subtypes in ductal carcinoma in situ of the breast and their relation to prognosis: a population-based cohort study. BMC cancer, 13(1), 1-9.