Ductal carcinoma in situ (DCIS) is the most common form of non-invasive breast cancer. For example, there are about 60 000 cases of DCIS in the United States each year.
This term consists of three parts:
Ductal means that it starts in the milk ducts.
Carcinoma is a tumor which starts in the skin or any tissues (including breast tissue) that cover or line internal organs of the body.
In situ means “in the original place”. This indicates that this cancer is non-invasive, i.e. it doesn’t spread to other parts of the body.
Who is at high risk to develop DCIS?
The risk of developing ductal carcinoma in situ is the same as the risk of developing invasive breast cancer. The risk factors include:
- a woman has never been pregnant,
- late pregnancy in women over 30 years,
- early menstruation,
- late menopause,
- relatives who had stage I breast cancer (mother, sisters, daughters),
- a hormone therapy for a long period of time (more than 5 years), especially in combination with estrogens and progesterones,
- abnormal genes which are responsable for the development of breast cancer (BRCA1 or BRCA2).
There are two reasons why this form of breast cancer is widespread and a number of cases are increasing. Today the life expectancy of women is increasing, as we know the risk is higher with age. Most women take mammography, the quality of which is getting better every year. It leads to early detection of this type of breast cancer, which is considered the early stage.
How is DCIS diagnosed?
DCIS generally has no signs or symptoms. A small number of people may have a lump in the breast or some discharge coming out of the nipple. According to the National Cancer Institute, about 80% of DCIS cases are found by mammography.
The fact is that the “old” cancer cells when dying do not have time to recover completely. As a result, this area is full of calcium salts (so called calcification), so microcalcifications are formed. These microcalcifications are just detected on a mammogram. If the results of mammography make doctors be alert, the next step of diagnosis is carried out – biopsy.
In case of ductal carcinoma in situ there are two kinds of biopsy (more invasive biopsies are rarely needed for DCIS):
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.
If a needle biopsy is not able to remove cells or tissue, or it does not give precise results (inconclusive), a more involved biopsy may be necessary. These biopsies are more like regular surgery than needle biopsies:
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.
DCIS diagnosis is not dangerous for woman’s life. It is invasive breast cancer and represents the early stage – stage 0, which is sometimes called “pre-cancer”. But still it is cancer which is characterized by uncontrolled growth of cells. Although this form of cancer is non-invasive, there is still risk that it becomes invasive, i.e. cancer cells invade other tissues. From 25 to 50% of women who had surgery (without radiotherapy) have risk in the future to develop invasive breast cancer. In most cases these relapses occur within 5 -10 years after detection of DCIS.
However, new type of breast cancer can develop even later – in 25 years! Typically it starts in the same place where DCIS was detected. This new cancer may be either invasive or non-invasive. Thus the main purpose of treatment is to minimize the risk of developing cancer in the future.
How is DCIS treated?
In most cases, treatment of ductal carcinoma in situ includes surgical removal of the tumor – a lumpectomy. The standard of surgery is that the edges of the resected (i.e. removed) breast tissue must be “clean” from any cancer cells. In order to reduce the risk of invasive cancer in most cases radiation therapy is used after surgery. If the tumor is hormone-dependent, a hormone therapy takes place in order to reduce the risk of recurrence or development of new breast cancer.
With treatment, ductal carcinoma in situ prognosis is usually excellent.