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 b ...

. 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 Carcinoma ''in situ'' (CIS) is a group of abnormal cells. While they are a form of neoplasm, there is disagreement over whether CIS should be classified as cancer. This controversy also depends on the exact CIS in question (i.e. cervical, skin, bre ...

" 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 Squamous-cell skin cancer, also known as cutaneous squamous-cell carcinoma (cSCC), is one of the main types of skin cancer along with basal cell cancer and melanoma. It usually presents as a hard lump with a scaly top but can also form an ulcer. ...

, 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 Stage or stages may refer to: Acting * Stage (theatre), a space for the performance of theatrical productions * Theatre, a branch of the performing arts, often referred to as "the stage" * ''The Stage'', a weekly British theatre newspaper * Sta ...

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 microscopic ...

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 diseas ...

. 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 A squamous intraepithelial lesion (SIL) is an abnormal growth of epithelial cells on the surface of the cervix, commonly called squamous cells. This condition can lead to cervical cancer, but can be diagnosed using a Pap smear or a colposcopy. It c ...

(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 microscopic ...

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. *

is a

squamous carcinoma Squamous-cell carcinomas (SCCs), also known as epidermoid carcinomas, comprise a number of different types of cancer that begin in squamous cells. These cells form on the surface of the skin, on the lining of hollow organs in the body, and on th ...

''in situ'' of the skin. * Colon polyps 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 mo ...

if left untreated. *

High-grade prostatic intraepithelial neoplasia High-grade prostatic intraepithelial neoplasia (HGPIN) is an abnormality of prostatic glands and believed to precede the development of prostate adenocarcinoma (the most common form of prostate cancer). It may be referred to simply as prostatic i ...

is equivalent to CIS of the prostate. *

Bronchioloalveolar carcinoma Adenocarcinoma in situ (AIS) of the lung —previously included in the category of "bronchioloalveolar carcinoma" (BAC)—is a subtype of lung adenocarcinoma. It tends to arise in the distal bronchioles or alveoli and is defined by a non-invasive ...

(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 causal, 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 us ...

s, but not by

oncologist Oncology is a branch of medicine that deals with the study, treatment, diagnosis and prevention of cancer. A medical professional who practices oncology is an ''oncologist''. The name's etymological origin is the Greek word ὄγκος (''ó ...

s or

surgeon In modern medicine, a surgeon is a medical professional who performs surgery. Although there are different traditions in different times and places, a modern surgeon usually is also a licensed physician or received the same medical training as ...

s, 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 and polypoid tumours of the bladder) can be removed using an

endoscope An endoscope is an inspection instrument composed of image sensor, optical lens, light source and mechanical device, which is used to look deep into the body by way of openings such as the mouth or anus. A typical endoscope applies several modern t ...

, 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. Radia ...

References

External links

{{Tumors Histopathology Carcinoma