Diagnosing DCIS usually involves a combination of procedures:
- Physical examination of the breasts: Your doctor may be able to feel a small lump in the breast during a physical examination, although a noticeable lump is rare with DCIS. In cases when DCIS cannot be felt during a physical exam, it can often be detected using mammography.
- Mammography: DCIS is usually found by mammography. As old cancer cells die off and pile up, tiny specks of calcium (called "calcifications" or "microcalcifications") form within the broken-down cells. The mammogram will show the cancer cells inside the ducts as a cluster of these microcalcifications, which appear either as white specks or as a shadow.
Biopsy: If you do have a suspicious mammogram, your doctor will probably want you to have a biopsy. There are two ways to get a biopsy done with only a little bit of surgery (more invasive biopsies are rarely needed for DCIS):
- Fine needle aspiration biopsy: A very small, hollow needle is inserted into the breast. A sample of cells is removed and examined under the microscope. This method leaves no scars.
- Core needle biopsy: A larger needle is inserted to remove several bigger samples of tissue from the area that looks suspicious. In order to get the core needle through the skin, the surgeon must make a tiny incision. This leaves a very tiny scar that is barely visible after a few weeks.
- Incisional biopsy: Incisional biopsy removes a small piece of tissue for examination.
- Excisional biopsy: Excisional biopsy attempts to remove the entire suspicious lump of tissue from the breast.
Biopsies are done only to make the diagnosis. If DCIS is diagnosed, more surgery is needed to ensure all of the cancer is removed along with "clear margins," which means that a border of healthy tissue around the cancer is also removed. Usually this means having lumpectomy, or in some cases (a large area of DCIS, for example), mastectomy.
After the biopsy, the pathologist analyzes the piece of breast tissue and reports back on the:
- type and grade of the DCIS: how abnormal the cells look when compared with normal breast cells, and how fast they are growing
- hormone-receptor status: Whether or not the cancer cells have receptors (proteins in a cell that receive messages from hormones) for the hormones estrogen and/or progesterone. If estrogen and/or progesterone receptors are present, this means that the cancer cells' growth is fueled by these hormones.
Type and grade of DCIS
All DCIS is considered stage 0 breast cancer — the earliest stage possible. "Stage" describes how far the cancer has spread beyond the site of the original tumor. Even though DCIS is always considered stage 0, it can be any size and be located in any number of areas inside the breast.
Knowing the type and grade of DCIS can help you and your doctor decide on the best treatment for you.
When a pathologist looks at the tissue removed during the biopsy, he or she determines whether or not any abnormal cells are present. If abnormal cells are present, the pathologist will note how different the cells look compared with normal, healthy breast cells. The image shows the range of possible findings, from normal cells all the way to invasive ductal cancer.
- Normal cells
- Ductal hyperplasia or "overgrowth" means that too many cells are present.
- Atypical ductal hyperplasia means that there are too many cells (hyperplasia) and they are starting to take on an abnormal appearance (atypical or "not typical").
- Ductal carcinoma in situ means that there are too many cells and they have the features of cancer, but they are still confined to the inside of the duct.
- DCIS-MI (DCIS with microinvasion) means that a few of the cancer cells have started to break through the wall of the duct. This is considered to be a slightly more serious form of DCIS.
- Invasive ductal cancer means that the cancer cells have broken beyond the breast duct. The breast cancer is no longer a DCIS but an invasive ductal carcinoma, the most common type of breast cancer.
There are three grades of DCIS: low or Grade I; moderate or Grade II; and high or Grade III. The lower the grade, the more closely the cancer cells resemble normal breast cells and the more slowly they grow. Sometimes it's difficult to figure out where the cells are on in the range from normal to abnormal. If the cells are in between grades, they may be called "borderline."
Grade I (low grade) or Grade II (moderate grade)
Grade I or low-grade DCIS cells look very similar to normal cells or atypical ductal hyperplasia cells. Grade II or moderate-grade DCIS cells grow faster than normal cells and look less like them. Grade I and Grade II DCIS tend to grow slowly and are sometimes described as "non-comedo" DCIS. The term non-comedo means that there are not many dead cancer cells in the tumor. This shows that the cancer is growing slowly, because there is enough nourishment to feed all of the cells. When a tumor grows quickly, some of its cells begin to die off.
People with low-grade DCIS are at increased risk of developing invasive breast cancer in the future (after 5 years), compared to people without DCIS. Compared to people with high-grade DCIS, however, people with low-grade DCIS are less likely to have the cancer return or have a new cancer develop. If more cancer does develop, it typically takes longer for this to happen in cases of low-grade DCIS versus high-grade.
There are different patterns of low-grade and moderate-grade DCIS:
- Papillary DCIS: The cancer cells are arranged in a finger-like pattern within the ducts. If the cells are very small, they are called micropapillary.
- Cribriform DCIS: There are gaps between cancer cells in the affected breast ducts (like the pattern of holes in Swiss cheese).
- Solid DCIS: Cancer cells completely fill the affected breast ducts.
Grade III (high-grade) DCIS
In the high-grade pattern, DCIS cells tend to grow more quickly and look much different from normal, healthy breast cells. People with high-grade DCIS have a higher risk of invasive cancer, either when the DCIS is diagnosed or at some point in the future. They also have an increased risk of the cancer coming back earlier — within the first 5 years rather than after 5 years.
High-grade DCIS is sometimes described as "comedo" or "comedo necrosis." Comedo refers to areas of dead (necrotic) cancer cells, which build up inside the tumor. When cancer cells grow quickly, some cells don’t get enough nourishment. These starved cells can die off, leaving areas of necrosis.
In addition to figuring out the type and grade of DCIS, the pathologist also will test your biopsy tissue for hormone receptors. This test determines whether or not the breast cancer has receptors for the hormones estrogen and progesterone. A positive result means that estrogen or progesterone (or both) fuels the cancer cells' growth. If the cancer is hormone-receptor-positive, your doctor is likely to recommend treatments that block the effects of estrogen or lower estrogen levels in the body.
Testing DCIS for hormone receptors is relatively new, however. Don't assume that your hospital will automatically perform this test. Be sure to ask your doctor to have the cancer tested this way.