Ductal carcinoma in situ (dcis)

Ductal carcinoma in situ (DCIS) is a pre-malignant condition of the breast.

The major difference between DCIS and invasive breast cancer is that the cancer cells have not yet developed the ability to invade and are thus contained within the breast duct in which they arise. Such cells cannot spread or metastasise and therefore local treatment to the breast can result in a complete cure.

DCIS is almost always invisible on examination and is detected primarily through mammography. The advent of regular screening programmes worldwide has given the impression that the incidence of DCIS has increased dramatically. In reality we are simply detecting breast cancer at the earliest (curable) rather than more advanced stage.

DCIS appears on a mammogram as tiny flecks of white calcium.

Calcification can result from any duct damage, which is remarkably common, and it is not always possible to determine the cause on mammogram although there are certain patterns that guide us. When there is any doubt, a diagnostic biopsy is recommended. Not all types of DCIS calcify and in such cases there is no mammographic marker for detection or surveillance. This type of DCIS is usually identified incidentally by the pathologist after a biopsy for another reason.

DCIS can be graded by the pathologist into high grade, or non-high (intermediate or low) grade, depending on the appearance of the cells. It is currently thought that high grade DCIS arises spontaneously and will progress to an invasive cancer within a few years. Low grade DCIS appears to represent a far more indolent process and arises as part of a continuum of changes within the breast and may progress to an invasive cancer over a longer time frame, probably 10 to 20 years.

Treatment Options

The mainstay of treatment for DCIS is surgical. A small lesion can be removed by a wide local excision as part of a breast conserving procedure. This almost always requires placement of a wire through the skin to localise the lesion and act as a guide during surgery and minimize the amount of tissue removed.

Depending somewhat on the size and type of DCIS, radiotherapy may be recommended after breast conserving surgery to decrease the chance of the disease recurring. Similarly, the anti oestrogen tablet Tamoxifen may also be prescribed. These issues will be fully discussed with you in conjunction with your histology. It is important after a wide local excision that the DCIS is completely removed and surrounded by a rim of normal breast tissue as a safety margin. Although the specimen is x-rayed during surgery to try and ensure this, the final judge is the pathologist. If the DCIS extends close to the resection margin under the microscope, further surgery will be recommended.

Sometimes the DCIS changes within the breast are widespread and a breast conserving procedure is not feasible. A mastectomy either with or without an immediate reconstruction will then be the surgical treatment of choice. It is not necessary to remove the lymph nodes as a staging procedure because DCIS does not spread. However, a limited staging procedure, in particular a sentinel node biopsy, may be recommended in certain cases.

Follow Up

The outlook following treatment for DCIS is excellent with up to a 98% cure rate. This is because DCIS is a pre-invasive condition and local treatment to the breast can completely eradicate the disease. A diagnosis of DCIS does mean there is an increased risk of developing DCIS or breast cancer in the other breast. Whilst this risk can be partly diminished by Tamoxifen treatment where appropriate, regular follow with annual mammography, ultrasound scan if required and regular clinical examination is mandatory.