The medical term “in situ” means “in place”. Lobular carcinoma in situ (LCIS) means that abnormal cancer cells are present, but they have not spread outside the tissues where they originally developed.
Once LCIS has been recognised this means that there is an increase in the number of these cells, their appearance is characteristic and the cells are behaving abnormally. These cells are contained in the milk-producing lobules of the breast, which are found within the lobes. The area involved does not go on to form invasive cancer.
Is LCIS a form of cancer?
Most people will categorise LCIS as stage 0 breast cancer – that is the earliest stage.
But – very importantly – LCIS is not actually considered the same thing as fully developed breast cancer. It is rather regarded as a marker or signal that breast cancer could develop at some time in the future. It is similar to the increased risk involved if the woman has a strong family history of breast cancer.
LCIS is also called lobular neoplasia – reflecting the belief that it is not actually cancer. Neoplasia is an abnormal growth in the number of any cell type.
But, having said all that, women who are recognised as having LCIS are known to have a higher chance of developing breast cancer later in life. The lifetime risk of a woman with LCIS developing some form of invasive breast cancer is 25%.
Is it a common condition?
The number of women who have been diagnosed with LCIS has increased in recent years. This is almost certainly because there is more awareness of breast cancer now, and women are screened more rigorously for the disease.
LCIS is often discovered by chance while a specimen of breast tissue is being examined after a suspicious finding on breast screening which led to a biopsy.
Most women with LCIS are not treated. They are closely monitored by their doctors with frequent breast examinations and mammography. This should be a similar programme to that used for women with a strong family history.
Women who have recognised LCIS should carefully examine their breasts each month and see their doctor immediately if they notice any changes.
Other options for those with LCIS are risk reducing mastectomy of both breasts and taking tamoxifen for five years.
Risk reducing mastectomy
Understandably, some women who have LCIS are very concerned about developing breast cancer in the future. This is particularly the case in women who have a strong family history of breast cancer and/or a proven genetic predisposition to the disease.
These women may opt for what is called a risk reducing mastectomy. That means the preventative removal of both breasts – the idea being that this markedly reduces the chances of breast cancer. This used to be called a prophylactic mastectomy. The name has been changed as mastectomy does not abolish the chance of developing breast cancer, but it does reduce the risk. It is impossible to remove every breast cell during surgery, so there is still a small chance that breast cancer can occur. This can be followed by immediate or delayed breast reconstruction.
Tamoxifen is a medication which is used in women who have breast cancer to prevent further spread of the disease. There is also evidence that it can be used in some high-risk women to prevent breast cancer. Its exact place in cancer prevention is still being sorted out and there are many ongoing trials that may help ascertain the answer. The early results suggest that it does reduce the risk of developing breast cancer, but the side effects mean that it is not suitable for all people.
Previously reviewed by Dr Jenny Edge, General Surgeon
Reviewed by Dr David Eedes, Oncologist, March 2011