Carcinoma ''in situ'' (CIS) is a group of abnormal cells. While they are a form of

neoplasm A neoplasm () is a type of abnormal and excessive growth of tissue. The process that occurs to form or produce a neoplasm is called neoplasia. The growth of a neoplasm is uncoordinated with that of the normal surrounding tissue, and persists ...

, there is disagreement over whether CIS should be classified as

cancer Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumors, which do not spread. Possible signs and symptoms include a lump, abnormal bl ...

. This controversy also depends on the exact CIS in question (i.e. cervical, skin, breast). Some authors do not classify them as cancer, however, recognizing that they can potentially become cancer. Others classify certain types as a non-invasive form of cancer. The term " pre-cancer" has also been used. These abnormal cells grow in their normal place, thus "''in situ''" (from Latin for "in its place"). For example, carcinoma ''in situ'' of the skin, also called Bowen's disease, is the accumulation of dysplastic epidermal cells within the epidermis only, that has failed to penetrate into the deeper dermis. For this reason, CIS will usually not form a

tumor A neoplasm () is a type of abnormal and excessive growth of tissue. The process that occurs to form or produce a neoplasm is called neoplasia. The growth of a neoplasm is uncoordinated with that of the normal surrounding tissue, and persists ...

. 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 (preinvasive 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. In the TNM classification, carcinoma ''in situ'' is reported as TisN0M0 ( stage 0).

Terminology

These terms are related since they represent the steps of the progression toward cancer: *

Dysplasia Dysplasia is any of various types of abnormal growth or development of cells ( microscopic scale) or organs (macroscopic scale), and the abnormal histology or anatomical structure(s) resulting from such growth. Dysplasias on a mainly microscopi ...

is the earliest form of precancerous lesion recognizable in a

biopsy A biopsy is a medical test commonly performed by a surgeon, interventional radiologist, or an interventional cardiologist. The process involves extraction of sample cells or tissues for examination to determine the presence or extent of a d ...

. Dysplasia can be low-grade or high-grade. High-grade dysplasia may also be referred to as carcinoma ''in situ''. *Invasive carcinoma, usually simply called

, has the potential to invade and spread to surrounding tissues and structures, and may eventually be lethal.

Examples

* Cervical squamous intraepithelial lesion (SIL), previously called cervical intraepithelial neoplasia (CIN), is a form of

dysplasia Dysplasia is any of various types of abnormal growth or development of cells ( microscopic scale) or organs (macroscopic scale), and the abnormal histology or anatomical structure(s) resulting from such growth. Dysplasias on a mainly microscopi ...

that can progress to

cervical cancer Cervical cancer is a cancer arising from the cervix. It is due to the abnormal growth of cells that have the ability to invade or spread to other parts of the body. Early on, typically no symptoms are seen. Later symptoms may include abnormal ...

. The term carcinoma ''in situ'' may be used interchangeably with high-grade SIL. * Ductal carcinoma ''in situ'' of the breast is the most common precancer in women. * Bowen's disease is a squamous carcinoma ''in situ'' of the skin. *

Colon polyps Colon commonly refers to: * Colon (punctuation) (:), a punctuation mark * Colon (anatomy), a major part of the large intestine, the final section of the digestive system Colon may also refer to: Places * Colon, Michigan, US * Colon, Nebraska, US ...

often contain areas of CIS that will almost always transform into

colon cancer Colorectal cancer (CRC), also known as bowel cancer, colon cancer, or rectal cancer, is the development of cancer from the colon or rectum (parts of the large intestine). Signs and symptoms may include blood in the stool, a change in bowel ...

if left untreated. * High-grade prostatic intraepithelial neoplasia is equivalent to CIS of the prostate. * Bronchioloalveolar carcinoma (BAC) of the lung is the only form of CIS that can kill directly because, in rare cases (the "pneumonic form"), it expands greatly and fills the lungs, preventing breathing and causing other dire effects on the host. Thus, the pneumonic form of BAC is a true

malignant Malignancy () is the tendency of a medical condition to become progressively worse. Malignancy is most familiar as a characterization of cancer. A ''malignant'' tumor contrasts with a non-cancerous ''benign'' tumor in that a malignancy is not s ...

entity, but is not "invasive" in the classical sense. For this reason, it is considered a form of CIS by

pathologist Pathology is the study of the causes and effects of disease or injury. The word ''pathology'' also refers to the study of disease in general, incorporating a wide range of biology research fields and medical practices. However, when used in t ...

s, but not by oncologists or surgeons, and inclusion of this form of cancer among the types of CIS is controversial.

Treatment

Carcinoma ''in situ'' is, by definition, a localized phenomenon, with no potential for

metastasis Metastasis is a pathogenic agent's spread from an initial or primary site to a different or secondary site within the host's body; the term is typically used when referring to metastasis by a cancerous tumor. The newly pathological sites, then, ...

unless it progresses into cancer. Therefore, its removal eliminates the risk of subsequent progression into a life-threatening condition. Some forms of CIS (e.g.,

colon polyps Colon commonly refers to: * Colon (punctuation) (:), a punctuation mark * Colon (anatomy), a major part of the large intestine, the final section of the digestive system Colon may also refer to: Places * Colon, Michigan, US * Colon, Nebraska, US ...

and polypoid tumours of the bladder) can be removed using an endoscope, without conventional surgical resection. 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 require major surgery, the best known being intraductal carcinoma of the breast (also treated with

radiotherapy Radiation therapy or radiotherapy, often abbreviated RT, RTx, or XRT, is a therapy using ionizing radiation, generally provided as part of cancer treatment to control or kill malignant cells and normally delivered by a linear accelerator. Ra ...

References

External links

{{Tumors Histopathology Carcinoma