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The TNM classification of carcinoma structures: An ontological assay
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Veröffentlicht: | 8. September 2005 |
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Gliederung
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The TNM classification carcinoma structures
TNM classifications have been developed for over 40 types of carcinoma structures for purposes of specifying stages in the development of such structures on the basis of tumor extent (T), lymph node spread (N) and distal metastasis (M). For example a T2N1M1 carcinoma structure will have a T2-stage structure has invaded the mucosa, submucosa and muscularis mucosa; an N1-stage structure has invaded one to three lymph nodes, an M1-structure has invaded distant organs such as the lung or liver.
Such TNM information is designed to serve within the Electronic Health Record (EHR) as a representation of the state of the patient at successive points in time. The goal is to reason with such information, for example to infer from past and present patient states information about the future progression pattern of the carcinoma.
Formal representation of carcinoma structures
A carcinoma can progress from one stage to the next in a variey of different ways. In the case of colon carcinoma, the tumour can first spread from the mucosa to submucosa and from the submucosa to the muscularis propria, from there to the regional lymph nodes and then cause metastasis in the lung. But the tumour can also cause lung metastasis before its spread to the lymph node. But there is a limited number of such alternative progressions which can be instantiated in actual patients with colon carcinoma, and we can represent such alternatives and the associated carcinoma structure at the class level.
1. Representation of pathological structure in various carcinoma stages
Each colon carcinoma structures can be represented in terms of its constituent entities and of the entities in its environment with which is associated. A different pattern of such entities will be characteristic of pathological structures in a T2 stage, for example, from those present in an N1 or M1 stage.
We can formulate such statements in terms of axioms of the form A → B & C & D ... as follows. Such axioms express ontological dependence relations, and they are to be read as signifying that if instances of the class A exist, then instances of the classes B, C, D ... also exist.
T2 colon carcinoma structure → (Portion of colon mucosa carcinoma pathological structure) & (Portion of colon submucosa carcinoma pathological structure) & (Portion of colon muscularis propria carcinoma structure)
N1 colon carcinoma structure → (1 lymph node with colon carcinoma metastatic structure) or (2 lymph node with colon carcinoma metastatic structure) or (3 lymph node with colon carcinoma metastatic structure)
M1 colon carcinoma structure → (Lung with colon carcinoma metastatic structure) or (Liver with colon carcinoma metastatic structure)
The T2N1M1 colon carcinoma structure then involves the collection of the corresponding three types of structures.
2. Representation of progression patterns of the carcinoma structure
Since there are multiple possibilities in which a particular instance of the class tumour can spread, the process of progression can be deterministically traced only backwards, that is once the tumour has progressed to an advanced stage, the preceding processes can be represented. However since each progression pathway is instantiated within many patients, the corresponding pattern of progression exists also as a class or universal. Thus, one pattern can be represented using the relation transformation_of taken from the Relation Ontology developed by the Open Biomedical Ontologies Consortium [Ref. 1].
T2N1M1 carcinomatous structure transformation_of T2N1M0 carcinomatous structure transformation_of T2N0M0 carcinomatous structure transformation_of T1N0M0 carcinomatous structure transformation_of TisN0M0 carcinomatous structure transformation_of Colon part
The above pattern is instantiated in all cases where a carcinoma in a portion of colon mucosa later invades an adjacent portion of colon submucosa which then invades the muscularis mucosa, is metastasized to a lymph node and then finally to a distant organ.
Discussion
The advantages of such representations include the ability of drawing inferences across these representations, integration of information present within the EHRs and representation of processes which occur while these structural transformations take place.
Acknowledgements
Work on this paper was carried out under the auspices of the Wolfgang Paul Program of the Alexander von Humboldt Foundation, of the EU Network of Excellence in Semantic Datamining, and also of the project “Forms of Life” sponsored by the Volkswagen Foundation.
References
- 1.
- Smith B, Ceusters W, Koehler J, Klagges B, Kumar A, Lomax J, Mungall C, Neuhaus F, Rector A, Rosse C. Relations in Biomedical Ontologies Genome Biology. (In press)