Grading (tumors)
Encyclopedia
In pathology
, grading is a measure of the cell appearance in tumor
s and other neoplasms. Some pathology grading systems apply only to malignant
neoplasms (cancer
); others apply also to benign
neoplasms. The neoplastic grading is a measure of cell anaplasia
(lack of differentiation
) in the sampled tumors arising from the hyperplasia
of normal tissue. Grading in cancer is distinguished from staging (Cancer staging
) that is instead a measure of the extent the cancer has spread.
Pathology grading systems classify the microscopic cell appearance abnormality, deviations in their rate of growth, degree of invasiveness and dissemination with the goal of predicting developments at tissue level (see also the 4 major histological changes in dysplasia
).
Cancer is a disorder of cell life cycle
alteration that leads (non-trivially) to excessive cell proliferation rates, typically longer cell lifespans and poor differentiation. The grade score (numerical: G1 up to G4) increases with the lack of cellular differentiation - it reflects how much the tumor cells differ from the cells of the normal tissue they have originated from (see 'Categories' below). Tumors may be graded on four-tier, three-tier, or two-tier scales, depending on the institution and the tumor type.
The histologic
tumor grade score along with the metastatic
(whole-body-level cancer-spread) staging are used to evaluate each specific cancer patient, develop their individual treatment strategy and to predict their prognosis. A cancer that is very poorly differentiated is called anaplastic.
The Gleason system, named after Donald Floyd Gleason
, used to grade the adenocarcinoma cells in prostate cancer is the most famous. This system uses a grading score ranging from 2 to 10. Lower Gleason scores describe well-differentiated less aggressive tumors.
Other systems include the Bloom-Richardson system (breast cancer) and the Fuhrman system (kidney cancer).
. Two researchers blindly measure the tumor length L and width W, in millimeters, with caliper
s. The depth is not measured and is assumed to equal the width W. The tumor's volume in cubic millimeters is then approximately 0.52W2L.
Pathology
Pathology is the precise study and diagnosis of disease. The word pathology is from Ancient Greek , pathos, "feeling, suffering"; and , -logia, "the study of". Pathologization, to pathologize, refers to the process of defining a condition or behavior as pathological, e.g. pathological gambling....
, grading is a measure of the cell appearance in tumor
Tumor
A tumor or tumour is commonly used as a synonym for a neoplasm that appears enlarged in size. Tumor is not synonymous with cancer...
s and other neoplasms. Some pathology grading systems apply only to malignant
Malignant
Malignancy is the tendency of a medical condition, especially tumors, to become progressively worse and to potentially result in death. Malignancy in cancers is characterized by anaplasia, invasiveness, and metastasis...
neoplasms (cancer
Cancer
Cancer , known medically as a malignant neoplasm, is a large group of different diseases, all involving unregulated cell growth. In cancer, cells divide and grow uncontrollably, forming malignant tumors, and invade nearby parts of the body. The cancer may also spread to more distant parts of the...
); others apply also to benign
Benign
A benign tumor is a tumor that lacks the ability to metastasize. Common examples of benign tumors include moles and uterine fibroids.The term "benign" implies a mild and nonprogressive disease. Indeed, many kinds of benign tumors are harmless to human health...
neoplasms. The neoplastic grading is a measure of cell anaplasia
Anaplasia
Anaplasia refers to a reversion of differentiation in cells and is characteristic of malignant neoplasms . Sometimes, the term also includes an increased capacity for multiplication. Lack of differentiation is considered a hallmark of aggressive malignancies. The term anaplasia literally means "to...
(lack of differentiation
Cellular differentiation
In developmental biology, cellular differentiation is the process by which a less specialized cell becomes a more specialized cell type. Differentiation occurs numerous times during the development of a multicellular organism as the organism changes from a simple zygote to a complex system of...
) in the sampled tumors arising from the hyperplasia
Hyperplasia
Hyperplasia means increase in number of cells/proliferation of cells. It may result in the gross enlargement of an organ and the term is sometimes mixed with benign neoplasia/ benign tumor....
of normal tissue. Grading in cancer is distinguished from staging (Cancer staging
Cancer staging
The stage of a cancer is a description of the extent the cancer has spread. The stage often takes into account the size of a tumor, how deeply it has penetrated, whether it has invaded adjacent organs, how many lymph nodes it has metastasized to , and whether it has spread to distant organs...
) that is instead a measure of the extent the cancer has spread.
Pathology grading systems classify the microscopic cell appearance abnormality, deviations in their rate of growth, degree of invasiveness and dissemination with the goal of predicting developments at tissue level (see also the 4 major histological changes in dysplasia
Dysplasia
Dysplasia , is a term used in pathology to refer to an abnormality of development. This generally consists of an expansion of immature cells, with a corresponding decrease in the number and location of mature cells. Dysplasia is often indicative of an early neoplastic process...
).
Cancer is a disorder of cell life cycle
Cell cycle
The cell cycle, or cell-division cycle, is the series of events that takes place in a cell leading to its division and duplication . In cells without a nucleus , the cell cycle occurs via a process termed binary fission...
alteration that leads (non-trivially) to excessive cell proliferation rates, typically longer cell lifespans and poor differentiation. The grade score (numerical: G1 up to G4) increases with the lack of cellular differentiation - it reflects how much the tumor cells differ from the cells of the normal tissue they have originated from (see 'Categories' below). Tumors may be graded on four-tier, three-tier, or two-tier scales, depending on the institution and the tumor type.
The histologic
Histology
Histology is the study of the microscopic anatomy of cells and tissues of plants and animals. It is performed by examining cells and tissues commonly by sectioning and staining; followed by examination under a light microscope or electron microscope...
tumor grade score along with the metastatic
Metastasis
Metastasis, or metastatic disease , is the spread of a disease from one organ or part to another non-adjacent organ or part. It was previously thought that only malignant tumor cells and infections have the capacity to metastasize; however, this is being reconsidered due to new research...
(whole-body-level cancer-spread) staging are used to evaluate each specific cancer patient, develop their individual treatment strategy and to predict their prognosis. A cancer that is very poorly differentiated is called anaplastic.
Categories
The most commonly used system of grading is as per the guidelines of the American Joint Commission on Cancer. As per their standards, the following are the grading categories.- GX Grade cannot be assessed
- G1 Well differentiated (Low grade)
- G2 Moderately differentiated (Intermediate grade)
- G3 Poorly differentiated (High grade)
- G4 Undifferentiated (High grade)
Systems
Grading systems are also different for each type of cancer.The Gleason system, named after Donald Floyd Gleason
Donald Floyd Gleason
Donald Floyd Gleason was an American pathologist known for his test, the Gleason score, a measure of malignancy of the prostate cancer.-References:...
, used to grade the adenocarcinoma cells in prostate cancer is the most famous. This system uses a grading score ranging from 2 to 10. Lower Gleason scores describe well-differentiated less aggressive tumors.
Other systems include the Bloom-Richardson system (breast cancer) and the Fuhrman system (kidney cancer).
Examples of grading schemes
| Grade 1 | Low grade | Well-differentiated |
| Grade 2 | Intermediate grade | Moderately-differentiated |
| Grade 3 | High grade | Poorly-differentiated |
| Grade 4 | Anaplastic | Anaplastic |
| Grade 1 | Low grade | Well-differentiated |
| Grade 2 | Intermediate grade | |
| Grade 3 | High grade | Poorly-differentiated |
| Grade 1 | Low grade | Well-differentiated |
| Grade 2 | High grade | Poorly-differentiated |
Tumor volume estimation
Experimental cancer studies involve the implantation of tumors subcutaneously in mice. Such studies require a simple mechanism by which to evaluate tumor burden. One such method is to approximate the tumor shape by a spheroidSpheroid
A spheroid, or ellipsoid of revolution is a quadric surface obtained by rotating an ellipse about one of its principal axes; in other words, an ellipsoid with two equal semi-diameters....
. Two researchers blindly measure the tumor length L and width W, in millimeters, with caliper
Caliper
A caliper is a device used to measure the distance between two opposing sides of an object. A caliper can be as simple as a compass with inward or outward-facing points...
s. The depth is not measured and is assumed to equal the width W. The tumor's volume in cubic millimeters is then approximately 0.52W2L.
See also
- TNM#Other parameters
- Tumor kinds that have their own grading system:
- TeratomaTeratomaA teratoma is an encapsulated tumor with tissue or organ components resembling normal derivatives of all three germ layers. There are rare occasions when not all three germ layers are identifiable...
- Teratoma
- Gleason scoreGleason scoreThe Gleason Grading system is used to help evaluate the prognosis of men with prostate cancer. Together with other parameters, it is incorporated into a strategy of prostate cancer staging which predicts prognosis and helps guide therapy. A Gleason score is given to prostate cancer based upon its...