Ductal carcinoma in situ (DCIS) is the presence of abnormal cells inside a milk duct in the breast.
DCIS is considered the earliest form of breast cancer. DCIS is noninvasive, meaning it hasn't spread out of the milk duct to invade other parts of the breast.
DCIS is usually found during a mammogram done as part of breast cancer screening or when there is another concern with a woman's breast. Because of increased screening with mammograms, the rate at which DCIS is diagnosed has increased dramatically in recent years.
While DCIS isn't life-threatening, it does require treatment to prevent the condition from becoming invasive. Most women with DCIS are effectively treated with breast-conserving surgery and radiation.
DCIS doesn't cause any signs or symptoms in most cases. However, DCIS can sometimes cause signs and symptoms, such as:
- A breast lump
- Bloody nipple discharge
DCIS is usually found on a mammogram and appears as small clusters of calcifications that have irregular shapes and sizes.
When to see a doctor
Make an appointment with your doctor if you notice a change in your breasts, such as a lump, an area of puckered or otherwise unusual skin, a thickened region under the skin, or nipple discharge. Contact your doctor to have it evaluated.
Ask your doctor when you should consider breast cancer screening and how often it should be repeated. Most groups recommend routine breast cancer screening beginning in your 40s. Talk with your doctor about what's right for you.
It's not clear what causes DCIS. DCIS forms when genetic mutations occur in the DNA of breast duct cells. The genetic mutations cause the cells to appear abnormal, but the cells don't yet have the ability to break out of the breast duct.
Researchers don't know exactly what triggers the abnormal cell growth that leads to DCIS. It's likely that a number of factors may play a part, including genes passed to you from your parents, your environment and your lifestyle.
Factors that may increase your risk of DCIS include:
- Increasing age
- Personal history of benign breast disease, such as atypical hyperplasia
- Family history of breast cancer
- First pregnancy after age 30
- Taking combination estrogen-progestin hormone replacement therapy for more than three to five years after menopause
- Genetic mutations that increase the risk of breast cancer, such as in the breast cancer genes BRCA1 and BRCA2