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{{short description|Index measuring the progression of cancer}}
Proliferation, as one of the [[Hallmarks of cancer|hallmarks]] and most fundamental biological processes in tumors,<ref>{{Cite journal|
== Mitotic index (also called mitotic count) ==
[[File:Mitosis in a neuroendocrine tumor.jpg|thumb|Mitosis in a [[neuroendocrine tumor]].]]
Mitotic indexing is the oldest method of assessing proliferation and is determined by counting the number of mitotic figures (cells undergoing mitosis) through a light microscope on [[H&E stain|H&E]] stained sections. It is usually expressed as the number of cells per microscopic field. Cells in the mitotic phase are identified by the typical appearance of their chromosomes in the cell during the mitotic phase of the cell cycle.<ref>{{Cite journal|last=Baak|first=J. P.|date=July 1990|title=Mitosis counting in tumors|journal=Human Pathology|volume=21|issue=7|pages=683–685|issn=0046-8177|pmid=2131787|doi=10.1016/0046-8177(90)90026-2}}</ref> Usually the number of mitotic figures is expressed as the total number in a defined number of high power fields, such as 10 mitoses in 10 high power fields. Since the field of vision area can vary considerably between different microscopes, the exact area of the high power fields should be defined in order to compare results from different studies. Accordingly, one of the main problems of counting mitosis has been the reproducibility. Thus, the need for standardized methodology and strict protocols is important to achieve reproducible results.<ref>{{Cite journal|
== Thymidine-labeling index ==
Thymidine-labeling indexing is determined by counting the number of tumor nuclei labeled on [[autoradiograph]]ed sections after incubating the tumor cells with thymidine. Rapidly proliferating cells readily update more [[radiolabeled]] Thymidine, which produces darker spots on the autoradiograph film.<ref>{{Cite journal|last=Silvestrini|first=R.|date=1994-10-01|title=Cell kinetics: prognostic and therapeutic implications in human tumours
== Bromodeoxyuridine assay ==
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== S-phase fraction evaluation ==
Evaluating DNA [[histogram]]s through flow cytometry provides an estimate of the fractions of cells within each of the phases in the cell cycle. Cell nuclei are stained with a DNA binding stain and the amount of staining is measured from the histogram.<ref>{{Cite journal|
== Immunohistochemical evaluation ==
The immunohistochemical detection of proliferation related proteins such as [[Ki-67 (protein)|Ki-67]] and proliferating cell nuclear antigen is a commonly used method to determine the proliferation index. Ki-67 is a nuclear antigen expressed in proliferating cells that is coded by the MKI67 gene on chromosome 10, and is expressed during the GI, S, G2, and M phases of the cell cycle. Cells are then stained with a Ki-67 antibody, and the number of stained nuclei is then expressed as a percentage of total tumor cells. It is recommended to count at least 500 tumor cells in the highest labeled area. The Ki-67 score closely correlates with other proliferation markers, and has been shown to have prognostic and predictive value for many different tumor types.<ref>{{Cite journal|
== Diagnostic role of proliferation index ==
The various methods of characterizing the proliferation index have found roles in both the diagnostic and prognostic evaluation of tumors. For instances, the number of mitotic cells is used to classify tumors. In general, a high proliferation index suggests malignancy and [[Grading (tumors)|high-grade tumors]].<ref>{{Cite journal|
==References==
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