ICD-O stands for International Classification of Diseases for Oncology an as the name suggests, it is an extension of ICD to better represent oncological diseases. It is often used in epidemiolgical cancer registries.
The TNM Classification of Malignant Tumours is a system to describe size, spread to lymph nodes and metastasis for solid tumors in oncology.
MedDRA (Medical Dictionary for Regulatory Activities) is a terminology mainly used to describe and classify Adverse Events in clinical trials. Its use is mandatory in the European Union.
Using Terminologies with the IMT
Importing all the terminologies is simple. Just select the staging server i2b2 instance and choose Import Data >> Import Standardterminologies.
Standard terminologies have no use on their own. If you don't have clinical data coded with a certain terminology, it's useless to import them.
The primary usage scenario is when you have data elements like admission diagnosis coded in ICD-10 or lab results coded in LOINC. Without an underlying terminology, you would have a very large lists of i2b2 leafs each representing one code. That is hard to handle for the user because of the sheer size, but also because nobody knows what all the codes stand for. Selecting all neoplasms for an i2b2 query, for instance, would mean to search and select about 150 terms.