Adenocarcinoma: Difference between revisions
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The vast majority of [[colorectal cancer]] is an adenocarcinoma. This is because the [[Colon (anatomy)|colon]] has numerous glands within the tissue. Normal colonic glands tend to be simple and tubular in appearance with a mixture of [[mucus]] secreting [[goblet cells]] and water absorbing cells. These glands are called glands because they secrete a substance into the [[lumen (anatomy)|lumen]] of the colon, this substance being mucus. The purpose of these glands are twofold. The first is to absorb water from the feces back into the blood. The second purpose is to secrete mucus into the colon lumen to lubricate the now dehydrated feces. This is crucial as a failure to lubricate the feces can result in colonic damage by the feces as it passes towards the rectum.<ref>{{cite book |author=Heath JE, Young B, Wheater PR, Lowe JN, Stevens A |title=Wheater's Functional histology: a text and colour atlas |publisher=Churchill Livingstone Elsevier |location=Edinburgh |edition=5th |year=2006 |pages=283 |isbn=0-443-06850-X }}</ref> |
The vast majority of [[colorectal cancer]] is an adenocarcinoma. This is because the [[Colon (anatomy)|colon]] has numerous glands within the tissue. Normal colonic glands tend to be simple and tubular in appearance with a mixture of [[mucus]] secreting [[goblet cells]] and water absorbing cells. These glands are called glands because they secrete a substance into the [[lumen (anatomy)|lumen]] of the colon, this substance being mucus. The purpose of these glands are twofold. The first is to absorb water from the feces back into the blood. The second purpose is to secrete mucus into the colon lumen to lubricate the now dehydrated feces. This is crucial as a failure to lubricate the feces can result in colonic damage by the feces as it passes towards the rectum.<ref>{{cite book |author=Heath JE, Young B, Wheater PR, Lowe JN, Stevens A |title=Wheater's Functional histology: a text and colour atlas |publisher=Churchill Livingstone Elsevier |location=Edinburgh |edition=5th |year=2006 |pages=283 |isbn=0-443-06850-X }}</ref> |
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When these glands undergo a number of changes at the genetic level, they proceed in a predictable manner as they move from benign to an invasive, malignant colon cancer. In their research paper "Lessons from Hereditary Colorectal Cancer", Vogelstein, et al., suggested that colon cells |
When these glands undergo a number of changes at the genetic level, they proceed in a predictable manner as they move from benign to an invasive, malignant colon cancer. In their research paper "Lessons from Hereditary Colorectal Cancer", Vogelstein, et al., suggested that colon cells lose the [[Adenomatous polyposis coli|APC]] tumor suppressor gene and become a small polyp. Next, they suggested that [[KRAS|k-Ras]] becomes activated and the polyp becomes a small, benign, adenoma. The adenoma, lacking the "carcinoma" attached to the end of it, suggests that it is a benign version of the malignant adenocarcinoma. The gastroenterologist uses a colonoscopy to find and remove these adenomas and polyps to prevent them from continuing to acquire genetic changes that will lead to an invasive adenocarcinoma. Volgelstein et al. went on to suggest that loss of the [[Deleted in Colorectal Cancer|DCC]] gene and of [[p53]] result in a malignant adenocarcinoma.<ref>{{cite journal |author=Kinzler KW, Vogelstein B |title=Lessons from hereditary colorectal cancer |journal=Cell |volume=87 |issue=2 |pages=159–70 |year=1996 |month=October |pmid=8861899 |doi= 10.1016/S0092-8674(00)81333-1|url=http://linkinghub.elsevier.com/retrieve/pii/S0092-8674(00)81333-1}}</ref> |
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Grossly, one will see a mass that looks of a different color than the surrounding tissue. Bleeding from the tumor is often apparent as the tumor tends to grow blood vessels into it in a haphazard manner via secretion of a number of [[angiogenesis]] promoting factors such as [[Vascular endothelial growth factor|VEGF]]. Histologically, |
Grossly, one will see a mass that looks of a different color than the surrounding tissue. Bleeding from the tumor is often apparent as the tumor tends to grow blood vessels into it in a haphazard manner via secretion of a number of [[angiogenesis]] promoting factors such as [[Vascular endothelial growth factor|VEGF]]. Histologically, |
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Revision as of 14:06, 13 July 2012
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| Adenocarcinoma | |
|---|---|
| Specialty | Oncology  |
Adenocarcinoma is a cancer of an epithelium that originates in glandular tissue. Epithelial tissue includes, but is not limited to, the surface layer of skin, glands and a variety of other tissue that lines the cavities and organs of the body. Epithelium can be derived embryologically from ectoderm, endoderm or mesoderm. To be classified as adenocarcinoma, the cells do not necessarily need to be part of a gland, as long as they have secretory properties. This form of carcinoma can occur in some higher mammals, including humans.[1] Well differentiated adenocarcinomas tend to resemble the glandular tissue that they are derived from, while poorly differentiated adenocarcinomas may not. By staining the cells from a biopsy, a pathologist can determine whether the tumor is an adenocarcinoma or some other type of cancer. Adenocarcinomas can arise in many tissues of the body due to the ubiquitous nature of glands within the body. While each gland may not be secreting the same substance, as long as there is an exocrine function to the cell, it is considered glandular and its malignant form is therefore named adenocarcinoma. Endocrine gland tumors, such as a VIPoma, an insulinoma, a pheochromocytoma, etc., are typically not referred to as adenocarcinomas, but rather, are often called neuroendocrine tumors. If the glandular tissue is abnormal, but benign, it is said to be an adenoma. Benign adenomas typically do not invade other tissue and rarely metastasize. Malignant adenocarcinomas invade other tissues and often metastasize given enough time to do so.
Diagnostic significance
A diagnosis of adenocarcinoma which is not further described, known as adenocarcinoma not otherwise specified or adenocarcinoma NOS, is significant because it displays when a cancerous process is present. However, it is not very useful for treatment decisions and prognosis, as these are determined by the tissue from which the tumour cells arose, i.e. the tissue of origin; an adenocarcinoma of the colon has a different prognosis and treatment than an adenocarcinoma of the ovary.
Adenocarcinoma not otherwise specified is often a preliminary diagnosis and can frequently be clarified by a pathologist with the use of immunohistochemistry.[2]
Cancer for which a primary site cannot be found is called cancer of unknown primary.
Histopathology
Examples of tissues where adenocarcinomas may arise:
Colon
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The vast majority of colorectal cancer is an adenocarcinoma. This is because the colon has numerous glands within the tissue. Normal colonic glands tend to be simple and tubular in appearance with a mixture of mucus secreting goblet cells and water absorbing cells. These glands are called glands because they secrete a substance into the lumen of the colon, this substance being mucus. The purpose of these glands are twofold. The first is to absorb water from the feces back into the blood. The second purpose is to secrete mucus into the colon lumen to lubricate the now dehydrated feces. This is crucial as a failure to lubricate the feces can result in colonic damage by the feces as it passes towards the rectum.[3]
When these glands undergo a number of changes at the genetic level, they proceed in a predictable manner as they move from benign to an invasive, malignant colon cancer. In their research paper "Lessons from Hereditary Colorectal Cancer", Vogelstein, et al., suggested that colon cells lose the APC tumor suppressor gene and become a small polyp. Next, they suggested that k-Ras becomes activated and the polyp becomes a small, benign, adenoma. The adenoma, lacking the "carcinoma" attached to the end of it, suggests that it is a benign version of the malignant adenocarcinoma. The gastroenterologist uses a colonoscopy to find and remove these adenomas and polyps to prevent them from continuing to acquire genetic changes that will lead to an invasive adenocarcinoma. Volgelstein et al. went on to suggest that loss of the DCC gene and of p53 result in a malignant adenocarcinoma.[4]
Grossly, one will see a mass that looks of a different color than the surrounding tissue. Bleeding from the tumor is often apparent as the tumor tends to grow blood vessels into it in a haphazard manner via secretion of a number of angiogenesis promoting factors such as VEGF. Histologically, tumours resembling original structures are classified as well differentiated. Tumour cells that lost any resemblance to original tissue, both in appearance and structure form, are denoted as poorly differentiated tumour cells. Regardless of the grade, malignant tumors tend to have a large nucleus with prominent nucleoli. There will also be a noticeable increase in the incidence of mitoses, or cell divisions.
Lung
Adenocarcinoma of the lung is currently the most common type of lung cancer in lifelong non-smokers.[5]
Urogenital
- Most cervical cancer is squamous cell cancer, but a sizeable minority of cervical cancers are adenocarcinomas.
- prostate
- urachus
- vagina
Other
- breast
- esophagus
- pancreas (95% of pancreatic cancers are ductal adenocarcinomas.)[6]
Etymology
The term adenocarcinoma is derived from 'adeno' meaning 'pertaining to a gland' and 'carcinoma', which describes a cancer that has developed in the epithelial cells.
See also
References
- ^ Fauquier D, Gulland F, Haulena M, Spraker T (2003). "Biliary adenocarcinoma in a stranded [[northern elephant seal]] (Mirounga angustirostris)". J Wildl Dis. 39 (3): 723–6. PMID 14567238.
{{cite journal}}: URL–wikilink conflict (help); Unknown parameter|month=ignored (help)CS1 maint: multiple names: authors list (link) - ^ Dabbs DJ, Silverman JF (2001). "Immunohistochemical Workup of Metastatic Carcinoma of Unknown Primary". Pathology Case Reviews. 6 (4): 146–53. doi:10.1097/00132583-200107000-00003.
{{cite journal}}: Unknown parameter|month=ignored (help) - ^ Heath JE, Young B, Wheater PR, Lowe JN, Stevens A (2006). Wheater's Functional histology: a text and colour atlas (5th ed.). Edinburgh: Churchill Livingstone Elsevier. p. 283. ISBN 0-443-06850-X.
{{cite book}}: CS1 maint: multiple names: authors list (link) - ^ Kinzler KW, Vogelstein B (1996). "Lessons from hereditary colorectal cancer". Cell. 87 (2): 159–70. doi:10.1016/S0092-8674(00)81333-1. PMID 8861899.
{{cite journal}}: Unknown parameter|month=ignored (help) - ^ Subramanian J, Govindan R (2007). "Lung cancer in never smokers: a review". Journal of Clinical Oncology. 25 (5): 561–70. doi:10.1200/JCO.2006.06.8015. PMID 17290066.
{{cite journal}}: Unknown parameter|month=ignored (help) - ^ "Detailed Guide, Pancreatic Cancer, What is Cancer of the Pancreas?". Retrieved 2009-21-2.
{{cite web}}: Check date values in:|accessdate=(help)
External links
