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Adenocarcinoma

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Adenocarcinoma

Adenocarcinoma
Micrograph of an adenocarcinoma showing mucin containing vacuoles. Pap test.
Classification and external resources
Specialty Oncology, pathology
ICD-9-CM 151.0, 182.0
ICD-O M8140/3
MeSH D000230

Adenocarcinoma[1] (; plural adenocarcinomas or adenocarcinomata ) is a type of cancerous tumor that can occur in several parts of the body. It is defined as neoplasia of epithelial tissue that has glandular origin, glandular characteristics, or both. Adenocarcinomas are part of the larger grouping of carcinomas. Cancers that are adenocarcinomas are often usually called by more precise terms omitting the word, where these exist. Thus invasive ductal carcinoma, the most common form of breast cancer, is adenocarcinoma but does not use the term in its name, but esophageal adenocarcinoma does, to distinguish it from the other common type of esophageal cancer, esophageal squamous cell carcinoma, which is not adenocarcinoma. Several of the most common forms of cancer are adenocarcinomas, and the various sorts of adenocarcinoma vary greatly in all their aspects, so that few useful generalizations can be made about them.

In the most specific germ layers (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. Adenocarcinoma is the malignant counterpart to adenoma, which is the benign form of such tumors. Sometimes adenomas transform into adenocarcinomas, but most do not.

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 owing to the ubiquitous nature of glands within the body, and, more fundamentally, to the potency of epithelial cells. 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.

Contents

  • Histopathology 1
    • Breast 1.1
    • Colon 1.2
    • Lung 1.3
    • Other 1.4
  • Etymology 2
  • See also 3
  • References 4
  • External links 5

Histopathology

Many seborrheic keratoses on back of person with Leser–Trélat sign due to colon cancer.

Examples of cancers where adenocarcinomas are a common form:

Breast

Most breast cancers start in the ducts or lobules, and are adenocarcinomas. The three most common histopathological types collectively represent approximately three-quarters of breast cancers:

Colon

Gross appearance of an opened colectomy specimen containing two adenomatous polyps (the brownish oval tumors above the labels, attached to the normal beige lining by a stalk) and one invasive colorectal carcinoma (the crater-like, reddish, irregularly-shaped tumor located above the label).
Histopathologic image of colonic carcinoid stained by hematoxylin and eosin.

The vast majority of colorectal cancers are adenocarcinomas. 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 is 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.[6]

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. Vogelstein et al. went on to suggest that loss of the DCC gene and of p53 result in a malignant adenocarcinoma.[7]

There will be a mass of a different color to 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 the original structures are classified as well differentiated. Tumour cells that have 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 mitosis, or cell divisions.

Lung

Pie chart showing incidence of adenocarcinoma of the lung (shown in yellow) as compared to other lung cancer types, with fractions of non-smokers versus smokers shown for each type.[8]

Nearly 40% of lung cancers are adenocarcinoma, which usually originates in peripheral lung tissue.[9] Most cases of adenocarcinoma are associated with smoking; however, among people who have smoked fewer than 100 cigarettes in their lifetimes ("never-smokers"),[10] adenocarcinoma is the most common form of lung cancer.[11] A subtype of adenocarcinoma, the bronchioloalveolar carcinoma, is more common in female never-smokers, and may have a better long-term survival.[12]

This cancer usually is seen peripherally in the lungs, as opposed to small cell lung cancer and squamous cell lung cancer, which both tend to be more centrally located.[13][14]

Other

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

  1. ^ From adeno-, "gland" and karkin(o)-, "cancerous" and -oma, "tumor".
  2. ^
  3. ^
  4. ^
  5. ^ a b c Percentage values are from United States statistics 2004. Subtype specific incidences are taken from Table 6 (invasive) and Table 3 (in situ) from . These are divided by total breast cancer incidence (211,300 invasive and 55,700 in situ cases) as reported from Breast Cancer Facts & Figures 2003–2004 [1]
  6. ^
  7. ^
  8. ^ Smokers defined as current or former smoker of more than 1 year of duration. See for percentages in numbers. Reference:
    • Table 2 in:
  9. ^
  10. ^
  11. ^
  12. ^
  13. ^ Chapter 13, box on morphology of adenocarcinoma in: 8th edition.
  14. ^

External links

  • Media related to at Wikimedia Commons
  • "Adenocarcinoma"—NCI Dictionary of Cancer Terms
  • Surgical Videos, Images and Case Studies of Adenocarcinoma of the Sinuses
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