Ductal carcinoma in situ (DCIS) makes up approximately 20% of newly diagnosed breast cancers. But patients are often confused about DCIS, what it means, and what to do about it. We asked MSK surgeon Melissa Pilewskie to provide some insight into the disease and its treatments.
Is DCIS a type of cancer?
This is actually a controversial topic, partly due to the language. It has the word “carcinoma” in the name, and it is classified as stage 0 cancer. DCIS refers to abnormal cells that are confined to the milk ducts. These cells have not yet spread into the surrounding normal breast tissue and cannot spread elsewhere in the body. It’s more of a precancer, or preinvasive lesion. So DCIS isn’t life-threatening, but it has the potential to become invasive cancer.Back to top
How is DCIS detected and diagnosed?
Most DCIS is detected from a mammogram that shows abnormal calcifications (small deposits of calcium) in the breast. The doctor may need to conduct additional imaging tests, such as ultrasound or MRI. These are used to determine the full extent of the disease.
DCIS is fully diagnosed by a needle biopsy. Pathologists examine the abnormal cells to determine the grade of the DCIS and the hormone-receptor status. DCIS is classified as low, intermediate, or high grade, depending on how abnormal the cells look under a microscope. High-grade DCIS cells are the most abnormal and grow the fastest.
Hormone-receptor status refers to whether the cancer cells have receptors for estrogen, progesterone, or both. The presence of these receptors suggests that these hormones fuel the growth of the cells. This affects how well a tumor may respond to certain drugs.Back to top
If someone has DCIS, what should be the first step in deciding on treatment?
A woman diagnosed with DCIS usually meets with a breast surgeon first. In addition to the tumor’s size, grade, and hormone-receptor status, the doctor will assess other risk factors for breast cancer: Should a patient get genetic testing, for inherited mutations such as BRCA1 or BRCA2, which are known to raise risk? Do they have a strong family history of the disease? All this information is important for deciding on the best treatment.Back to top
What’s the most effective treatment for DCIS?
Surgery is nearly always the first treatment for DCIS, and it is very effective. There are two types of surgery used for DCIS. The less-invasive option is a lumpectomy, in which a surgeon removes the area that’s abnormal as well as a little bit of the normal tissue around it. This is called a margin. The other is a mastectomy, which involves removing the entire breast.
Most women with DCIS undergo a lumpectomy, possibly followed by additional treatments. In some cases, a mastectomy is recommended, especially if the DCIS covers a large area or appears in multiple spots throughout the breast. With either of these surgeries, the survival rate is excellent. Our job is to figure out which type of surgery makes sense.Back to top
Is surgery always necessary for DCIS?
We nearly always recommend surgery. Even though DCIS is noninvasive and not life-threatening, it has the potential to turn into something more serious. Furthermore, when we do surgery for DCIS, 20% of the time we find an invasive cancer in the tissue that we did not know about from the needle biopsy. For this reason, at MSK the only time we don’t do surgery for DCIS is when we think the risks of the surgery don’t outweigh the benefits. For example, some patients might not be able to tolerate the procedure because of their age or other health problems.
After surgery, what other treatments might be needed?
For women who have a mastectomy for DCIS, there is usually no need for additional treatment because the risk of the cancer coming back (recurrence) is very low. After a lumpectomy, there is still a risk that the DCIS may come back or become invasive cancer. To reduce this risk, the two main treatments are radiation therapy and, if the DCIS cells have the estrogen receptor, hormone therapy. These drugs include tamoxifen (Nolvadex®), which blocks the estrogen receptor, and aromatase inhibitors, which block estrogen production.
Probably the hardest decision faced by women with DCIS is whether to have one of these additional treatments after a lumpectomy. A lot of factors must be considered, including the size and grade of the DCIS, how close the DCIS cells were to the final margin, and the age of the person at diagnosis. Younger women have a higher risk of recurrence. And then as a doctor, I need to consider how each of my patients thinks about risk. For example, a 10% risk of recurrence in the next ten years can mean completely different things to two different people. Some women want to do everything to lower their risk, while others are happy to just have it watched closely.Back to top
What are some advantages of receiving treatment for DCIS at MSK?
At MSK, we have a very thoughtful approach to personalizing adjuvant therapies for each woman with DCIS. The doctors and patients make all the treatment decisions as a team. Much of the research determining risk factors for DCIS-related recurrence was done at MSK. We’ve tried to figure out who really needs additional treatments, such as radiation or hormone therapy. There are side effects to everything, so we really balance the pros and cons. It’s not one size fits all. We want people to have the best quality of life while staying cancer free.Back to top