What is Ductal Carcinoma In-Situ?
Ductal carcinoma in situ (DCIS) is known as intraductal carcinoma. It is also called pre-invasive and noninvasive breast cancer. DCIS is the earliest stage of breast cancer, stage 0 breast cancer. In DCIS, the normal breast cells start to “go bad.” These abnormal cells look like cancer cells under the microscope but are confined within the milk ducts. There are no abnormal cells outside of the ducts’ basement membranes, or ducts’ foundation layers. The abnormal cells associated with DCIS do not spread into the surrounding breast tissue. DCIS does not spread to the lymph nodes or metastasize (meaning it doesn’t spread to other parts of the body).
The image below depicts progression from normal breast, DCIS, to invasive breast cancer.
How is DCIS diagnosed?
DCIS is usually found by screening mammography. On mammography, DCIS often appears as abnormal calcifications. DCIS can present as a palpable mass. And DCIS is the cause of nipple discharge in some patients. The nipple discharge associated with DCIS may be clear or bloody and is frequently from one specific opening (duct) in the nipple.
What are the grades and types of DCIS?
There are three grades of DCIS:
- Low grade
- Intermediate grade
- High grade
Grade is determined by how the DCIS looks underneath the microscope. The higher the grade, the more disorderly the appearance of the cells. High grade DCIS is more likely to develop into invasive cancer than low grade DCIS.
There are several types of DCIS. The specific type of DCIS describes a feature seen with the type. Some examples of type are:
- Comedocarcinoma, which shows a lot of dead cells within the ducts
- Nodular DCIS, which shows up as a nodule (or lump)
- Papillary carcinoma in-situ, which is associated with papillary growths within ducts
Some DCIS will respond to hormonal stimulation. The types of DCIS that contains hormone receptors on its surfaces (called estrogen and progesterone receptor positive) can be treated with medications called hormone blocking agents. Tamoxifen is the medication that has traditionally been used to treat these hormone receptor positive DCIS.
For DCIS that does not respond to hormones (estrogen receptor and progesterone receptor negative DCIS), hormone blocking agents will not be effective. The patients with estrogen and progesterone receptor negative DCIS will not need Tamoxifen, or other types of hormone blocking medications.
Does all DCIS become invasive carcinoma?
No. One review noted that 14-53% of DCIS will develop into invasive breast cancer in 10 years. And physicians cannot accurately predict which patients with DCIS will go on to develop invasive breast cancer. This is because the natural history of DCIS is not clear.
How is DCIS treated?
The current standard of care for DCIS is surgery. Either lumpectomy or mastectomy are the surgical options. It is recommended to remove all of the DCIS that can be detected. For those with large areas of DCIS or DCIS in multiple parts of the breast, mastectomy may be recommended. Mastectomy is not necessary in patients with small areas of DCIS. Radiation therapy following lumpectomy, or at the time of lumpectomy, is frequently recommended. Hormone blocking therapy also plays a role in treating DCIS.
Is radiation needed following a lumpectomy?
Radiation after lumpectomy decreases DCIS and invasive cancer recurrence to the same breast by about 50%. Excision alone may be appropriate treatment for some patients with low grade DCIS, especially for those who are over 70 years of age. For younger patients, the omission of radiation therapy in selected cases is currently being studied. Patients with high grade DCIS usually have radiation therapy after their lumpectomy, or in the case of intraoperative radiation therapy, at the time of the lumpectomy.
Is DCIS treated with medication?
For estrogen receptor positive and estrogen receptor positive DCIS, hormone blocking medications will be effective. Tamoxifen is offered to women who are still having menstrual cycles. For women who are no longer have menstrual cycles (postmenopausal), other medications called aromatase inhibitors (including Arimidex and Exemestane) may be used as well as Tamoxifen. These medications will not benefit patients with estrogen and progesterone receptor negative DCIS.
Ductal Carcinoma In-Situ is stage 0 breast cancer that can be effectively treated. Like other breast cancer, treatment is tailored to the patient and their individual needs and concerns.