The medical term “in situ” means “in place”. Ductal carcinoma in situ (DCIS) refers to cancer cells which are confined to the milk ducts of the breast which have not spread to the tissue of the breast or to any other part of the body, such as the lymph nodes.
This is the most common type of non-invasive breast cancer in women.
Detection and diagnosis
DCIS is often first detected when a woman has a mammogram. It may appear as tiny specks of calcium – called microcalcifications – which are too small to be felt during physical examination.
When DCIS is suspected it is confirmed by breast biopsy.
Is DCIS a cancer?
DCIS is regarded as a stage 0 cancer – that is the earliest form of breast cancer. It is best though of as a “pre-cancer”, a contained cancer which has not spread beyond the ductal system of the breast to the lymph nodes or other areas of the body. In time, DCS will become a cancer.
The aim of management of DCIS is prevention of breast cancer. Without treatment, the majority of women with DCIS will go on to get cancer. If it is adequately managed, very few women should have further problems.
As with any other form of breast cancer, DCIS is not an emergency. There is time to learn about the condition and to discuss the best form of treatment with your doctor.
DCIS refers to a family of cancers which occurs in the breast ducts. There are two categories – comedo and non-comedo.
Comedo is a term which refers to the fact that when these breast tumours are cut across, the dead (necrotic) cells inside them can be squeezed out – like a blackhead or comedo on the skin.
Comedo DCIS tends to be more aggressive than non-comedo DCIS.
DCIS is also graded into 3 categories: high, intermediate and low grade. This gives some indication of how quickly changes in the area may occur and is also an indication of what type of cancer may develop if it is left to progress. High grade DCIS tends to develop into high grade cancer. Conversely, low grade DCIS tends to develop into low grade cancer.
There are several general factors used to determine the treatment of DCIS:
- The size of the tumour
- The type of tumour
- The histological grade of the tumour – this means whether the tumour cells are in a well-organised pattern or totally disorganised – the latter is usually associated with a more aggressive cancer.
- Whether the cancer has oestrogen or progesterone receptors present
- The age of the patient
DCIS is by definition, a non-invasive cancer. This means that it has not even spread as far as the tissue within the breast. However, DCIS may become invasive cancer. If this happens, it may spread to the lymph nodes and the blood stream.
The primary management of DCIS is surgery. Some cases of DCIS can be treated using a lumpectomy, usually followed by radiation, or a mastectomy. As DCIS is not invasive, surgery is rarely performed on the lymph nodes.
Can tamoxifen be used?
Tamoxifen has been used for nearly thirty years to treat breast cancer. More recently the drug has been used to treat early breast cancer after lumpectomy or mastectomy.
Tamoxifen is an “anti-oestrogen” preparation. Some types of cancer have receptors to the female hormone oestrogen on them. They use this hormone to grow and reproduce. If the action of oestrogen can be blocked, then the cancer will either not grow at all, or will grow more slowly. Tamoxifen “competes” with oestrogen to bind to the receptors on the cancer cells. This helps to slow the growth and reproduction of any remaining cancer cells after surgery.
There are trials that are looking at the role of tamoxifen in prevention of breast cancer. The early results have shown that tamoxifen is effective in decreasing the incidence of breast cancer in women who are known to be high risk (e.g. women with DCIS), but that there are side effects that means it can not be used for all women.
Can breast cancer recur after DCIS has been treated?
DCIS can recur after the initial treatment. It most commonly recurs in the same area and may recur as an invasive cancer rather than as DCIS.
Women with DCIS who have been treated with lumpectomy are at a slightly higher risk of recurrence of DCIS in the same breast than those who had a mastectomy. But it is important to remember that studies have shown that women who have a lumpectomy for DCIS rather than a mastectomy are at no greater risk of dying from cancer, provided that the area was completely removed.
Reviewed by Dr Jenny Edge, General Surgeon, Bsc, MB BS, FRCS (Edin), M Med (Stell.), October 2011