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Carcinoma in situ
Carcinoma in situ (CIS) is an early form of carcinoma defined by the absence of invasion of surrounding tissues. In other words, the neoplastic cells proliferate in their normal habitat, hence the name 'in situ' (Latin for 'in its place'). For example, carcinoma in situ of the skin, also called Bowen's disease is the accumulation of neoplastic epidermal cells within the epidermis only.
For this reason, CIS will usually 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). Some CIS, however, form tumors, for example colon polyps or papillary cancer of the bladder.
Many forms of invasive carcinoma (the most common form of cancer) originate from a CIS lesion. Therefore, CIS is considered a precursor or incipient form of cancer that may, if left untreated long enough, transform into a malignant neoplasm.
When explaining a laboratory report to a patient, most doctors will refer to CIS as pre-cancer, not cancer. However, because most forms of CIS have a real potential to turn into invasive carcinoma, doctors will usually recommend that the lesion be completely removed. Therefore, CIS is usually treated much the same way as a malignant tumor.
Additional recommended knowledge
Dysplasia vs carcinoma in situ vs invasive carcinoma
These terms are related since they represent the three steps of the progression toward cancer:
Examples of carcinomata in situ
Carcinoma in situ is, by definition, localized, with no potential for metastasis unless it progresses into a true cancer. Therefore, its removal eliminates the risk of cancer. It can be compared to uprooting a tree, easy when a young sapling, more difficult later.
Some forms (e.g. colon polyps and polypoid tumors of the bladder) can be removed using an endoscope, without true surgery. Dysplasia of the uterine cervix is removed by excision (cutting it out) or by burning with a laser. Bowen's disease of the skin is removed by excision. Other forms of CIS require major surgery, the best known being Intraductal carcinoma of the Breast. The most difficult form of CIS is Bronchioloalveolar carcinoma of the Lung, which requires the removal of large parts of the lung. When too large, it cannot be removed and often kills its host.
Intraductal carcinoma of the Breast is also treated with radiotherapy.
|This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Carcinoma_in_situ". A list of authors is available in Wikipedia.|