One out of every five new breast cancer diagnoses each year is ductal carcinoma in situ (DCIS). This is an uncontrolled growth of cells within the breast ducts. The phrase "in situ" means "in its original place." This cancer is noninvasive and has not yet made it to breast tissue outside of the ducts.
Ductal carcinoma in situ is the earliest stage at which breast cancer can be diagnosed. It's known as Stage 0 breast cancer. The prognosis for women diagnosed with this form of breast cancer is excellent. The vast majority of women diagnosed with ductal carcinoma in situ are cured.
Even though ductal carcinoma in situ is noninvasive, it is imperative that women with the disease receive medical treatment because it can be a precursor of invasive cancer. Experts believe that 25% to 50% of women with DCIS will later develop an invasive breast cancer within 10 years of the DCIS diagnosis. The invasive cancer usually develops in the same breast and in the same quadrant of the breast that the DCIS first occurred.
How is ductal carcinoma in situ diagnosed?
Ductal carcinoma in situ does not usually cause the formation of a lump in the breast that can be felt upon examination. Signs and symptoms of DCIS include breast pain and/or a bloody discharge from the nipple. About 80% of cases are found by mammograms. Mammograms detect tiny bits of calcium that develop in dead cancer cells. As more and more cancer cells age and die, these calcifications grow. On the mammogram, they appear as a shadowy area.
If your mammogram suggests that you may have ductal carcinoma in situ, your doctor should recommend a biopsy. The purpose of the biopsy is to analyze the cells in the suspicious area for cancer and confirm the diagnosis. Biopsies for DCIS are typically done using needles to remove tissue samples from the breast.
After confirming that you have ductal carcinoma in situ, your doctor may recommend other tests. These tests may include an ultrasound or MRI of the breast to gather more information about your cancer. Based on the results of various tests, your doctor will be able to determine the size of your tumor and how much of your breast is involved in the cancer.