Carcinoma in situ
Carcinoma in situ also known as in situ neoplasm is a group of abnormal cells which grow in their normal place, thus called as “in situ” which means in its place. Carcinoma in situ is a form of neoplasm but there is disagreement over whether it should be classified as cancer. Some classify them as non-invasive cancer and some do not classify them as cancer. The term “pre-cancer” has also been used. Carcinoma in situ of skin is known as Bowen’s disease, is the accumulation of dysplastic epidermal cells within the epidermis only, which has failed to penetrate into the deeper dermis. For this reason, CIS will not form a tumor. Rather, the lesion is flat (in the skin, cervix, etc.) or follows the existing architecture of the organ (in the breast, lung, etc.). Exceptions include CIS of the colon (polyps), the bladder (pre-invasive papillary cancer), or the breast (ductal carcinoma in situ or lobular carcinoma in situ). Many forms of CIS have a high probability of progression into cancer and therefore removal may be recommended; however, progression of CIS is known to be highly variable and not all CIS becomes invasive cancer.