What is ductal carcinoma in situ (DCIS)?

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DCIS starts in the lining of the milk ducts. It is a non-invasive breast cancer, which means the cancer is only located in the breast and has not spread throughout the body.

Breastcancer.org notes that people with DCIS have a higher chance of developing invasive breast cancer in the future, and it may also return within 5–10 years of the first diagnosis.

Learn more about stage 0 breast cancer here.

Researchers are unsure of the exact cause of DCIS, though they think it could run in families.

Doctors diagnose 60,000 cases of DCIS a year, and it accounts for one in five new breast cancer cases. While this number is relatively high, it may be partly due to the fact that people are living longer and receiving more mammography screenings than ever before.

DCIS does not present with many symptoms, and doctors usually first detect it from a mammogram. Mammography screenings detect around 90% of DCIS cases. However, some people may notice a lump in their breast or nipple discharge as initial symptoms.

Other ways a doctor will diagnose DCIS include a physical examination of the breast and a biopsy. A biopsy will help a healthcare professional identify what stage the DCIS is at.

Hormone-receptor status

A pathologist may also check the biopsy for hormone receptors. The test will help to determine whether the cancer cells have receptors for estrogen and progesterone, which are types of hormones.

If the test result is positive, it means that the hormones help the cancer cells to grow. In this case, the doctor may prescribe treatments that help block the effects of estrogen or lower the levels of estrogen in the body.

Breast cancer cells may have one, both, or none of the following receptors:

• ER-positive: This means the cells have estrogen receptors.
• PR-positive: This means the cells have progesterone receptors.
• Hormone receptor-positive: Healthcare professionals use this term if the cancer cells have one or both of the above hormone receptors.
• Hormone receptor-negative: Healthcare professionals use this term if the cancer cells have neither of the above hormone receptors.

There are three grades of DCIS. They are:

• Grade I, or low grade: This is when the DCIS cells appear similar to normal cells and grow slowly. People with low-grade DCIS have an increased chance of developing invasive breast cancer after 5 years.
• Grade II, or moderate grade: Moderate-grade cells grow faster and appear less similar to normal cells.
• Grade III, or high grade: At this stage, the cells grow quickly and appear different from healthy cells. Those with high-grade DCIS have a higher chance of developing invasive cancer and an increased chance of recurring cancer within the first 5 years.

Low and moderate-grade DCIS cells have different patterns:

• Papillary: The cells are arranged in a finger-like pattern.
• Cribiform: There are gaps between the cells.
• Solid: The cancer cells fill the breast duct entirely.

Healthcare professionals do not typically use chemotherapy to treat DCIS.

Treatment of DCIS varies depending on how much cancer is in the breast and if the DCIS is aggressive.

Treatment options include:

Lumpectomy (breast-conserving surgery) with radiation therapy

In this procedure, the surgeon will remove the tumor and some healthy breast tissue close by as a precaution.

Sometimes they may also remove the lymph nodes and request a biopsy to confirm that the cancer has not spread. Healthcare professionals call this a sentinel lymph node biopsy (SLNB). They are more likely to do this if the tumor is large.

After surgery a person will receive radiation therapy to destroy any remaining cells.

Lumpectomy

Sometimes, a person will only receive a lumpectomy, However, this is not standard treatment and doctors reserve this for people with a very low-grade DCIS.

A person should speak with their doctor about radiation therapy if they are unsure about this approach.

Mastectomy

If the DCIS is in many areas of the breast, or the tumor is large, a surgeon may remove the entire breast.

Usually, a surgeon will also perform an SLNB to confirm if any cancer cells are in the lymph nodes. Sometimes, a person receives reconstructive surgery immediately after the mastectomy or will have it as a separate procedure.

Depending on individual circumstances, a person would not usually receive radiation therapy after a mastectomy.

Hormonal therapy after surgery

If doctors know the cancer uses estrogen and progesterone to grow, they will likely suggest hormonal therapy.

This treatment blocks tumor receptors that bind to these hormones, or reduces the amount of estrogen and progesterone in the body. A person may continue hormonal therapy for 5 years after surgery.

The survival rate of DCIS is high because people receive their breast cancer diagnosis early and begin treatment before the cancer progresses to a more invasive type.

The vast majority of people with DCIS can expect to have a normal life expectancy. However, they are at a higher risk of developing invasive breast cancer in the future in comparison with the general population.

In instances where a person does not receive treatment for DCIS, the cancer could progress to an invasive type and spread to other parts of the body.

According to Cancer Research UK, it is rare for DCIS to return after a mastectomy.

Breastcancer.org notes that those who undergo a lumpectomy without radiation have a 25–30% chance of experiencing a recurrence. With radiation therapy, this is lowered to 15%.

If breast cancer returns after DCIS treatment, there is a 50% chance that it will not be invasive breast cancer.

The researchers of a 2019 meta-analysis found the chance of developing invasive breast cancer is increased if:

• a person is premenopausal
• there were residual tumor cells after the treatment
• the DCIS was previously high grade, or grade III

According to a 2019 article in the journal Cancer, compared to white women, Black women are more likely to:

• die of breast cancer after DCIS
• develop invasive breast cancer after DCIS
• develop ER-positive or PR-positive invasive breast cancer after DCIS

Additionally, basal-like tumors disproportionately affected Black women, and their chance of developing triple-negative breast cancer doubled after DCIS.

The researchers note that the higher mortality rates may be, in part, due to the higher chance of developing more aggressive breast cancer types, such as triple-negative breast cancer. However, it is also the result of health inequities, including a lack of access to competent oncology care and delays in treatment.

Learn more about how breast cancer affects Black women here.

Screening for DCIS is incredibly important, as the sooner a person receives their diagnosis the earlier their treatment can start.

The Centers for Disease Control and Prevention (CDC) run a Nation Breast and Cervical Early Detection Program (NBCCEDP) for people with low incomes or those who are underinsured or have no insurance.

The program also covers:

• people whose yearly income is below 250% of the federal poverty level
• people who are between 40–64 years old
• other people who are younger or older that may need breast screening

Find out more about breast cancer screening programs here.

LCIS, like DCIS, is another type of in situ breast cancer. A doctor would detect it through a biopsy.

Researchers are unsure if LCIS is a type of pre-cancer as it rarely transforms into an invasive cancer. However, people with LCIS have a higher risk of developing breast cancer in the future.

Doctors tend to find LCIS after conducting a biopsy for another reason, as it does not usually show up on mammograms and is rarer than DCIS.

Because people with DCIS have a higher risk of developing invasive breast cancer in the future, they should remember to physically examine their breasts for lumps and speak with their doctor if they notice any changes in the breast, a lump, or discharge from the nipple.

People should be aware that mammography screenings detect most DCIS cases as the condition is often symptomless. As a result, a person should be sure to have regular screenings.

DCIS is a type of breast cancer that starts in the breast ducts.

Doctors usually catch DCIS early, which means the survival rate is high.

If a person cannot get a mammography screening due to their insurance coverage, they should look up the CDC’s NBCCEDP initiative.

After recovering from DCIS, a person should continue to self-examine their breasts and speak with a doctor if they notice any changes.