What is Carcinoma in situ, [KAR-si-NO-ma in SYE-too]Cancer that involves only cells in the tissue in which it began and that has not spread to nearby tissues.
Carcinoma in Situ is defined as cancer that is only present in the cells it has it has began growing in and has not spread to other nearby tissue. This means it has not yet formed a tumor but is considered high grade and may have the potential to do so if left untreated.
If you were to look it up Carcinoma in Situ (often shortened to CIS) it can mean different things when associated with different kinds of cancer as far as treatment and potential for progression.
In bladder cancer it can appear visually as a velvety or red patch on the bladder or it may not even be visible to the eye at all. This is one of the reasons that your Urologist will often do what they call random biopsies, this means they will take small samples of tissue at random sites within the bladder. This way even if it cannot be seen by the eye it will be identified in the pathology report as it can be seen under a microscope. CIS is often found when there is a tumor being removed but it can be your main diagnosis without a tumor being present.
If it is found that you have CIS and do not have muscle invasive bladder cancer it is often treated with immunotherapy where an agent is placed in the bladder by catheter and held for a period of time. Statistically it has been found that CIS has a high rate of response to this type of treatment.
If you have CIS it is very important that you are faithful with having your checkups on time to make sure that it has not reoccurred and if it has that it is properly treated so that it does not progress.
From Weill Cornell Medical College