Carcinoma in situ describes a cancer in the very earliest stage. At this point, the cancer is quite small and has not invaded the tissues around it.
Cancer develops in several stages. A cancer begins when a single cell becomes cancerous. This happens when the central control of the cell is damaged. The cell begins to grow and multiply out of control. When enough of these cells are produced, they form a tumor. The tumor will eventually grow large enough to press on the tissue around it. The tumor will also invade and destroy the tissue around it. When a tumor has formed but has not begun to invade tissue, it is said to be "in situ," which means in place. Some cancers may stay in this stage for a long time. Most cancers, however, do not stay in situ for long and begin to spread. Cancers found in situ are the easiest to cure because they have not spread.
Carcinoma in situ is so small that there may be no symptoms. Carcinoma in situ of the breast may be found when a small change is noted on a mammogram. Carcinoma in situ of the bladder may be found when the internal wall of the bladder is examined for other reasons. Routine Pap smears of the cervix are done to find carcinoma in situ of the cervix.
The risks for developing a particular type of carcinoma in situ are the same as the risks for developing that type of cancer.
Some cancers cannot be prevented. Other cancers, such as bladder cancer, lung cancer, and throat cancer, are related to smoking. Avoiding tobacco products in all forms may help prevent these cancers.
For the cancers that cannot be prevented, finding the cancer in an early stage is very important to ensuring successful treatment. Routine breast self-exams, mammograms, Pap smears, and testicular self-exams can help to find cancers in an early stage.
Carcinoma in situ is diagnosed by taking a sample, called a biopsy, of the area. This sample is sent to a laboratory to see if it is cancerous.
Carcinoma in situ is likely to invade nearby tissue and spread to other parts of the body. Cancer that has spread, also known as metastasized, is fatal if it is not treated.
There is no risk to others from a person who has carcinoma in situ.
Removing all of the cancerous tissue is the primary treatment. This can be done by surgery. Removing the cancer can also be done by destroying the area chemically, with chemotherapy, or with radiation therapy.
Because the affected area is small, the side effects and discomfort are minimal.
Sometimes, the presence of one carcinoma in situ can mean that others will form. The doctor will want to monitor the person closely to see whether carcinoma in situ comes back at the same spot or whether a new one develops somewhere else.
The affected area will be closely monitored. For example, a woman with carcinoma in situ of the cervix will need more frequent Pap smears than a woman without cancer. A woman with carcinoma in situ of the breast will need more frequent mammograms. A person who has had carcinoma in situ of the bladder will require frequent examinations of the bladder wall.