How Is Ductal Carcinoma In Situ (DCIS) Treated?

Ductal carcinoma in situ (DCIS), or stage 0 breast cancer, is considered a non-invasive or pre-invasive cancer. Treatment—such as surgery, radiation therapy, hormone-blocking medications, or chemotherapy—may be necessary to ensure it does not turn into invasive breast cancer.

DCIS occurs when cells in a milk duct have mutated and multiplied to look like cancer cells. About one in five newly diagnosed breast cancers is DCIS, which usually stays confined to the duct.

1. Surgery

DCIS can often be removed with a lumpectomy, which spares the surrounding breast tissue. Surgeons aim to remove all cancerous cells plus a 2-millimeter margin to lower recurrence risk.

In some cases, if DCIS affects multiple ducts or is large, a mastectomy may be recommended.

After diagnosis and surgery, the next step is to assess the risk of invasive cancer returning. Large DCIS areas, around 2-2.5 centimeters (20-25 millimeters), are at higher risk. Smaller ones are low risk.

"With DCIS lesions [bigger] than 20-25 millimeters, the general recommendation is for more than just surgery," Julia White, MD, a radiation oncologist at the University of Kansas Medical Center, told Health.

Additional treatment may include radiation and hormone therapy. Some DCIS may never progress, so some people may opt to skip surgery and use a watch-and-wait approach.

2. Radiation Therapy

A healthcare provider can determine whether further treatment is needed through genomic testing or by looking at factors like age, family history, and tumor size and grade.

Radiation therapy is "a little more tailored to the type of DCIS and the type of patient, and there's been a downward trend of getting less radiation or avoiding it completely, if possible," Marleen Meyers, MD, medical oncologist and director of the Perlmutter Cancer Center Survivorship Program at NYU Langone Health, told Health.

It is typically part of treatment after breast-conserving surgery (BCS). It does come with side effects and has not been shown to extend survival in people with DCIS. Instead, it is only been shown to reduce the risk of another cancer occurring.

People should weigh the pros and cons carefully, added Dr. Meyers. It is important to make the best individual decision.

3. Hormone Therapy

Taking drugs that block the production of sex hormones—like tamoxifen or aromatase inhibitors—can reduce the risk of a DCIS recurrence or a future invasive cancer. These medicines also cause side effects, and they will not lower the risk for everyone.

To tell if these drugs will be effective, a DCIS tumor should be tested to see if it has estrogen and progesterone receptors.

"The majority of women will have positive hormone receptors," said Dr. Meyers. "For those who don't, we don't do risk reduction with these drugs because they're not likely to be advantageous."

These drugs have not been shown to actually extend the survival rate of people with DCIS—only to reduce the risk of another cancer.

People should consider their individual risk factors to decide whether additional treatment is worth it to them, said Dr. Meyers, "and if they feel miserable on these medicines, we can always stop them."

4. Chemotherapy

DCIS is non-invasive, so chemotherapy is not used as a treatment option. In less than 1% of all cancer diagnoses, pathology reports show that cancer cells in a DCIS lesion have started to break through the wall of the duct, known as DCIS with micro-invasion, or DCIS-MI.

Chemotherapy may be beneficial in these cases. More studies are needed to confirm its effectiveness.

5. Vaccine

People diagnosed with DCIS may one day get a vaccine to help reduce their risk of developing invasive breast cancer in the future. More clinical trials are underway.

Researchers have been hoping that a vaccine may be able to stimulate the immune system and keep early DCIS from progressing beyond the milk duct. If trials are successful, experts said it could eventually be an alternative to surgery and radiation therapy for some people.

How Is DCIS Diagnosed?

For most, DCIS is picked up on routine mammograms. "Typically, the mammogram finds a calcification—a small cluster of cells with abnormal shapes and sizes—and then it is diagnosed after a biopsy," said Dr. Meyers.

DCIS can grow large enough to form a lump. Some people may also have unusual nipple discharge or Paget's disease, which causes the nipple skin to become thick and dry.

People are getting treated earlier, so there are fewer chances for DCIS to become invasive. "We've seen a huge increase in the number of DCIS cases diagnosed in the last 20 years," said Dr. White.

Pathologists disagree about 8% of the time when diagnosing breast biopsy samples, with DCIS being the most difficult. About 19% of DCIS cases are over-interpreted and 12% under-interpreted.

Non-invasive breast lesions are considered a "gray zone," and experts have called for revised guidelines.

Nuclear Grade

Healthcare providers will consider the nuclear grade of DCIS, which is determined by looking closely at the nuclei of the cells removed during a biopsy. There are three grades of DCIS:

• Low, or grade 1—which looks the most like normal, healthy cells
• Intermediate, or grade 2
• High, or grade 3—which looks the most abnormal and grows the fastest

High-grade DCIS is sometimes described as "comedo" or "comedonecrosis," which means that dead cells have built up inside the fast-growing tumor. The higher the grade, the greater the chance a person has of also having invasive breast cancer, either with the DCIS or at some point in the future.

What Is the Prognosis?

DCIS is non-invasive, so the chances of recovery and long-term survival after treatment are generally high. A study found a 98% survival rate after 10 years.

The prognosis is also "extremely good" with surgery, radiation therapy, or hormone therapy.

Stage 0 breast cancer still comes with risks. People with DCIS are at long-term risk for invasive breast cancer and death due to breast cancer within 20 years.

"Whatever caused the cells to mutate will generally occur in more than one duct, and sometimes, those mutated cells can break through a duct and become invasive breast cancer," said Dr. Meyers.

DCIS affects the milk ducts, but it does not necessarily mean you cannot produce milk after treatment. "As long as a woman has surgery alone, and assuming the lesion is not too close to the nipple, DCIS should not cause problems with conceiving or breastfeeding," said Dr. Meyers.

A Quick Review

DCIS, or stage 0 breast cancer, is a non-invasive form of breast cancer that affects breast ducts. It shares some risk factors with invasive breast cancers and can affect anyone of any age.

Treatment for DCIS can be similar to that for other breast cancers in an effort to prevent it from turning into an invasive form.