What is Stage 0 Breast Cancer?

By Sally Wadyka. Medically reviewed by Tom Iarocci, MD. May 7th 2016

As uncomfortable as a mammogram may be when screening for breast cancer, there is one thing you can take comfort in knowing: After receiving one, you can expect the results to be clear-cut. Your doctor will say either the exam shows something abnormal or, hopefully, shows no signs of cancer.

If your mammogram results come back abnormal, don’t fret. It may sound scary, but an abnormal mammogram doesn’t always mean you have breast cancer. In the case of ductal carcinoma in situ (DCIS), also called stage 0 breast cancer, there are abnormal cells or tumors in the breast, but they’re located only inside the milk ducts. This system of pathways that connect the milk-producing lobes of the breasts to the nipples have an outer membrane that serves as a barrier.

“If the tumor is contained and has not grown through that membrane, then it doesn’t have access to spread into the lymph system,” explains Lisa Jacobs, M.D., associate professor and surgical oncologist at the Johns Hopkins Breast Center in New York.


Finding stage 0 breast cancer

DCIS is the most common type of noninvasive breast cancer. Because DCIS rarely feels like palpable lumps you might find during a breast self-exam, it’s nearly always detected during a routine mammogram. Still, a couple symptoms can offer clues.

First, if you experience any nipple discharge, see your doctor, as this can be a sign. Another condition called Paget’s disease, which causes an eczema-like rash, can be indicative of DCIS. In fact, Jacobs says about 90 percent of people who have Paget’s also have DCIS.

If you’ve been told your mammogram results came back abnormal, you may be called back in for further testing. Follow-up tests can include a diagnostic mammogram, ultrasound, MRI or biopsy.

Although DCIS is considered noninvasive, it could develop into an invasive tumor. Tumors are graded by how aggressive they look under the microscope, and the likelihood of DCIS progressing to invasive breast cancer may depend on what grade it is when detected, Jacobs says. It’s estimated that if left untreated, Grade 1 tumors may become invasive 25 percent of the time, Grade 2 tumors may become invasive about 50 percent of the time, and Grade 3 tumors may become invasive about 75 percent of the time.

How can you treat DCIS?

Diagnosis and subsequent treatment of stage 0 breast cancer is somewhat controversial. One problem is that there’s no clear answer as to whether DCIS would progress and turn invasive if left untreated. There are currently no conclusive tests to help determine which tumors will become invasive and which won’t.

“We are working on testing technologies for tumor markers, but we’re just not there yet,” says Jacobs.

In the meantime, because DCIS might turn into invasive breast cancer, almost every case is treated. Doctors usually recommend surgery, and the prognosis is usually excellent.  Typically, a lumpectomy is performed to remove the tumor or cluster of abnormal cells, followed by radiation. If the DCIS is estrogen receptor-positive — meaning that estrogen fuels the cancer cells’ growth — your doctor may also prescribe the medication tamoxifen, a type of hormone therapy, following surgery to help reduce the risk of recurrence in either breast.

If you have a strong family history of breast cancer, your doctor may opt for more radical treatment, such as a mastectomy of the affected breast or even a double mastectomy. In treating people who also have Paget’s disease, the nipple must be removed, and many times the surgeon will prefer to remove the entire breast. And sometimes, other conditions may warrant a mastectomy.

“Even when DCIS is contained within the ductal system, if the abnormal cells are pervasive, we worry we can’t cut it out completely without removing the breast,” says Jacobs.

The good news is that if the disease is discovered at stage 0 or even stage 1, most patients can avoid chemotherapy, removal of lymph nodes and mastectomy while still having a nearly 100 percent survival rate.

Take the next steps

The first step in treating DCIS is to ensure you’re getting regular mammograms. Because DCIS often doesn’t cause noticeable lumps, a mammogram is the best way to diagnose it.

If your mammogram and subsequent tests show you have DCIS, don’t worry. Remember, DCIS is considered stage 0 breast cancer — zero being the key word here. And while DCIS is noninvasive, it’s imperative you get treated.

Each case of DCIS is different, so be sure to talk to your doctor openly and honestly. Discuss any concerns or questions you have. It might also help to bring a loved one with you to your appointments, so he or she can ask questions you haven’t thought of, or at the very least, act as a second pair of ears. Together, you and your health care practitioner can assess the risks and determine which treatment options are best for you.

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