Ductal carcinoma in situ (DCIS)

DCIS diagnosis 

In Australia, DCIS is a common diagnosis, with more than 1,500 women diagnosed with DCIS each year (BreastScreen monitoring report, 2023). 

In itself, DCIS isn’t life threatening. However, having DCIS can increase your risk of developing invasive breast cancer later in life. DCIS doesn’t usually appear as a breast lump or breast change. As a result, most women with DCIS do not show any signs or symptoms of having breast cancer.

Mammogram and/or ultrasound are the most common ways in which DCIS is diagnosed. If DCIS is suspected, a biopsy is usually required to confirm whether DCIS is present. Pathologists usually attribute a grade to DCIS. The grade indicates the patterns of cancer cell growth and how fast the cells are growing. Based on what the DCIS cancer cells look like under a microscope, DCIS can be graded as high, intermediate or low.

If left untreated, high-grade DCIS is likely to develop into invasive breast cancer. Low or intermediate grades of DCIS may remain as they are – essentially dormant – for many years. In some cases, however, low or intermediate grades of DCIS can develop into invasive breast cancer.

While the size and grade of DCIS can help doctors predict whether the cancer is likely to become invasive, there are no certain answers. Unfortunately, it is not currently possible to identify or know if a person with DCIS will go on to develop invasive breast cancer. 

Risk of breast cancer 

Not every woman with DCIS will develop invasive breast cancer. Your risk of developing invasive breast cancer is, however, increased if you have been diagnosed with DCIS.

Research is currently being undertaken internationally to help health professionals better predict which women with DCIS are more likely to develop invasive breast cancer and how long after their diagnosis of DCIS this would be likely to occur. 

Treatment for DCIS 

Women with DCIS are recommended treatment because DCIS has the potential to become invasive breast cancer. Currently, it is not reliably known for certain which women with DCIS will develop invasive breast cancer if they are not treated. While some women may never develop invasive breast cancer if not treated, others may.

The goal of DCIS treatment is to ensure the abnormal cells in the milk ducts do not spread to the breast tissue and become invasive breast cancer and to prevent the abnormal cells from returning at a later time.

Breast-conserving surgery is a common treatment for DCIS. This is also called a lumpectomy, partial mastectomy or wide local incision. Following breast conserving surgery most people will be recommended radiotherapy to destroy any abnormal cells that may be left in the breast after surgery. Mastectomy may be recommended if the DCIS is widespread within the milk ducts.

Removal of lymph nodes is generally not recommended as a treatment for DCIS. If DCIS is extensive and you require a mastectomy, or if your surgeon is unsure about the presence of invasive breast cancer, you may be offered a sentinel node biopsy.

Chemotherapy is generally not used to treat DCIS after surgery. If your DCIS is oestrogen receptor-positive (which means that the cancer needs oestrogen to grow), oestrogen-blocking treatments may be recommended. These include tamoxifen or aromatase inhibitors such as letrozole, anastrozole or exemestane.