DCIS (ductal carcinoma in situ): what it is, symptoms, treatment and outlook

Macmillan describes DCIS as the earliest changes to cells which might then become breast cancer. It says it is not a life-threatening condition, but treatment is usually recommended to stop it developing into breast cancer. Breast cancer usually starts in the cells lining the lobules, where milk is made, and the ducts that carry milk to the nipple. In DCIS the lining is replaced by abnormal cells, which are completely contained in the ducts and lobules and have not broken through their walls or spread into surrounding breast tissue.

Cancer Research UK explains that doctors may describe DCIS in different ways, including pre-invasive, non-invasive, ductal intraepithelial neoplasia (DIN), intraductal cancer and stage 0 breast cancer. DCIS and invasive breast cancer are not the same thing: in invasive breast cancer the cells have broken out of the ducts and spread into surrounding tissue, with a chance of reaching lymph nodes or other parts of the body.

Macmillan says that if DCIS is not treated, over time there may be more changes to the cells so that it spreads into the breast tissue around the ducts and becomes an invasive breast cancer. Not every untreated DCIS will do so, but because doctors cannot tell for certain which will, they usually advise treating it. Having DCIS also means a slightly higher risk of cancer elsewhere in the same breast or in the other breast.

Macmillan says a multidisciplinary team (MDT) of specialists meets to discuss the best treatment, and then your doctor or specialist nurse explains the options and side effects so you can decide together. The team needs to know the size of the DCIS, whether it is in one part of the breast, its grade and whether it has hormone receptors. The main treatment is surgery to remove the DCIS, and the aim is to remove it and reduce the risk of it developing into invasive cancer.

Cancer Research UK says surgery is the main treatment for DCIS and that you might have an area of the breast removed (breast-conserving surgery) or the whole breast (mastectomy). Your surgeon might recommend a particular operation or give you a choice, and some people prefer to keep as much of their breast as possible while others prefer the whole breast removed because it makes them feel more confident that the DCIS has gone.

Macmillan says a WLE and a mastectomy work equally well for treating DCIS, so your surgeon and breast care nurse may ask you to decide which operation feels right. After surgery the edges of the removed tissue are examined; if DCIS cells are close to or at the edge, another operation may be needed. If you have a mastectomy, you will usually also have a sentinel lymph node biopsy, and you may be able to have a new breast shape made during the operation or later.

Cancer Research UK says that after a mastectomy DCIS almost never comes back, while for women who just have the area of DCIS removed the chance is a bit higher. It stresses that your doctor can give you more information about the chance in your case.

Macmillan says DCIS usually has no symptoms and is usually found through changes seen on a mammogram taken as part of the NHS breast screening programme. A small number of people go to their GP with symptoms and are referred for a mammogram. Cancer Research UK lists the possible symptoms: a lump in the breast, discharge from the nipple which might be blood stained, and a rash on the nipple that may be red and scaly.

Macmillan says if you have Paget's disease, a condition affecting the skin of the nipple that causes redness, discharge or bleeding and sometimes itching, you may also have DCIS and will usually be referred for a mammogram. Always see your GP if you notice any breast symptoms.

Macmillan says that in the UK women and people assigned female at birth aged 50 to 70 are invited to NHS breast screening every 3 years, and DCIS is now diagnosed much more often than it used to be, with 1 in 5 screen-detected breast cancers (20%) being DCIS. If a mammogram shows changes you are referred to a breast clinic for further tests, which may include more mammograms focused on the area (from different angles or with magnification), a breast ultrasound including the lymph nodes in the armpit, and a biopsy, where a small piece of tissue or sample of cells is checked for cancer cells.

Cancer Research UK says doctors use the grade and stage to decide treatment. Grade is how abnormal the cells look under a microscope: low (more slowly growing), intermediate or high (more quickly growing). Doctors think high-grade DCIS is more likely to come back after treatment and to spread into surrounding breast tissue.

Macmillan says that after treatment you will have yearly mammograms for 5 years (of your other breast if you had a mastectomy). After 5 years, if you are 50 or over, you usually have mammograms through the NHS breast screening programmes, and younger women usually continue with yearly mammograms until they reach 50. Cancer Research UK says check-ups depend on your situation and that everyone who has had treatment for early breast cancer should have a copy of a written care plan. Contact your healthcare team between appointments if you notice a symptom or are worried.

Macmillan also notes that your treated breast will look and feel different, that your cancer doctor or nurse will usually advise against contraception that contains hormones, and that treatment can affect your sex life and body image. Difficulties often improve slowly, and you can ask your nurse for support.

Macmillan says the exact cause of DCIS is unknown, but certain risk factors increase the chance of developing it, and they are similar to those for invasive breast cancer. Having one or more risk factors does not mean you will definitely get DCIS, and having none does not mean you will not. DCIS is likely to be caused by a combination of risk factors rather than one. Cancer Research UK adds that one clinical trial found some evidence of a genetic cause of DCIS and invasive breast cancer but that more research is needed.

Cancer Research UK says researchers are trying to find out whether people with low or intermediate risk DCIS need to have treatment at all, and points to clinical trials. For now Macmillan says doctors usually advise treating DCIS because they cannot yet identify which cases would become invasive. Ask your breast team whether any trials you could join are relevant to your situation.

See your GP if you notice a breast lump, discharge from the nipple (especially if blood stained), a red scaly rash on the nipple or any other breast change. Macmillan advises always seeing your GP with any breast symptom. If you have had DCIS, contact your breast care team promptly if you notice changes in either breast between check-ups. Call 999 for severe symptoms such as heavy bleeding or sudden severe breathlessness.

Most DCIS is found through NHS breast screening or a GP referral and treated in an NHS breast unit by a multidisciplinary team, with a breast care nurse as a key contact. The usual route to a breast clinic is via screening recall or a GP referral. Some people have private mammograms, consultations or surgery; treatment follows the same principles, and the pathology and plan should still be discussed by a breast MDT and shared with your GP. Macmillan and Cancer Research UK provide information and nurse helplines for people with DCIS.