Editing Cancer (section)

== Classification ==
{{further|List of cancer types|List of oncology-related terms}}{{Refimprove section|date=January 2025}}[[File:Histopathology of adenocarcinoma.png|thumb|240px|A large proportion of cancers are [[adenocarcinoma]]s, with typical [[histopathology]] features shown, although they vary substantially from case to case.]]
Cancers are classified by the [[List of distinct cell types in the adult human body|type of cell]] that the tumor cells resemble and is therefore presumed to be the origin of the tumor. These types include:
* [[Carcinoma]]: Cancers derived from [[epithelium|epithelial]] cells. This group includes many of the most common cancers and include nearly all those in the [[breast cancer|breast]], [[prostate cancer|prostate]], [[lung cancer|lung]], [[pancreas]] and [[Colorectal cancer|colon]]. Most of these are of the [[adenocarcinoma]] type, which means that the cancer has [[gland]]-like differentiation.
* [[Sarcoma]]: Cancers arising from [[connective tissue]] (i.e. [[bone]], [[cartilage]], fat, [[nerve]]), each of which develops from cells originating in [[mesenchyme|mesenchymal]] cells outside the [[bone marrow]].
* [[Lymphoma]] and [[leukemia]]: These two classes arise from hematopoietic (blood-forming) cells that leave the marrow and tend to mature in the [[lymph node]]s and blood, respectively.<ref>{{cite book | vauthors = Varricchio C | title = A cancer source book for nurses |publisher=Jones and Bartlett Publishers |location=Boston |year=2004 |page=229 |isbn=978-0-7637-3276-9 |url={{google books |plainurl=y |id=jkqdgZcF9qcC |page=229}}}}</ref>
* [[Germ cell tumor]]: Cancers derived from [[pluripotent]] cells, most often presenting in the [[testicular cancer|testicle]] or the [[ovarian cancer|ovary]] ([[seminoma]] and [[dysgerminoma]], respectively).
* [[Blastoma]]: Cancers derived from immature "precursor" cells or embryonic tissue.

Cancers are usually named using ''-carcinoma'', ''-sarcoma'' or ''-blastoma'' as a suffix, with the Latin or Greek word for the [[organ (anatomy)|organ]] or tissue of origin as the root. For example, cancers of the liver [[parenchyma]] arising from malignant epithelial cells is called ''[[hepatocellular carcinoma|hepatocarcinoma]]'', while a malignancy arising from primitive liver precursor cells is called a [[hepatoblastoma]] and a cancer arising from fat cells is called a ''[[liposarcoma]]''. For some common cancers, the English organ name is used. For example, the most common type of breast cancer is called ''[[mammary ductal carcinoma|ductal carcinoma of the breast]]''. Here, the adjective ''ductal'' refers to the appearance of cancer under the microscope, which suggests that it has originated in the milk ducts.

[[Benign tumor]]s (which are not cancers) are named using ''-oma'' as a suffix with the organ name as the root. For example, a benign tumor of smooth muscle cells is called a ''[[leiomyoma]]'' (the common name of this frequently occurring benign tumor in the uterus is ''[[uterine fibroid|fibroid]]''). Confusingly, some types of cancer use the ''-noma'' suffix, examples including [[melanoma]] and [[seminoma]].

Some types of cancer are named for the size and shape of the cells under a microscope, such as giant cell carcinoma, [[spindle cell carcinoma]] and [[small-cell carcinoma]].

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File:Breast cancer gross appearance.jpg|An invasive [[ductal carcinoma]] of the breast (pale area at the center) surrounded by spikes of whitish scar tissue and yellow fatty tissue
File:Colon cancer 2.jpg|An invasive [[colorectal carcinoma]] (top center) in a [[colectomy]] specimen
File:Lung cancer.jpg|A [[squamous-cell carcinoma]] (the whitish tumor) near the [[bronchi]] in a lung specimen
File:BreastCancer.jpg|A large invasive [[Mammary ductal carcinoma|ductal carcinoma]] in a [[mastectomy]] specimen
File:Histopathology of squamous-cell carcinoma.png|[[Squamous cell carcinoma]] with typical histopathology features.
File:Histopathology of small cell carcinoma, annotated.png|Histopathology of [[small-cell carcinoma]], with typical findings.<ref>Image by Mikael Häggström, MD. Source for findings: {{cite web|url=https://www.pathologyoutlines.com/topic/lungtumorsmallcell.html|title=Lung – Small cell carcinoma|website=Pathology Outlines| vauthors = Underwood CI, Glass C }} Last author update: 20 September 2022</ref>
</gallery>