International Classification of Diseases for Oncology, 3rd Edition (ICD-O-3)


Used principally in tumour or cancer registries for coding the site (topography) and the histology (morphology) of neoplasms, usually obtained from a pathology report.

Classification structure

A multi-axial classification of the site, morphology, behaviour, and grading of neoplasms.

The topography axis uses the ICD-10 classification of malignant neoplasms (except those categories which relate to secondary neoplasms and to specified morphological types of tumours) for all types of tumours, thereby providing greater site detail for non-malignant tumours than is provided in ICD-10. In contrast to ICD-10, the ICD-O includes topography for sites of haematopoietic and reticuloendothelial tumours.

The morphology axis provides five-digit codes ranging from M-8000/0 to M-9989/3. The first four digits indicate the specific histological term. The fifth digit after the slash (/) is the behaviour code, which indicates whether a tumour is malignant, benign, in situ, or uncertain (whether benign or malignant).

A separate one-digit code is also provided for histologic grading (differentiation).

Administrative status

Creation date: 1976

Last date change: 2000

Change description: Updates in nomenclature and Classification, with emphasis of changes on haematologic and neurologic neoplasms.

Reference documents

Available indexes:

A single combined alphabetical index for topography and morphology.

Available formats:

Training and training materials:

The European Network of Cancer Registries has provided training courses with the assistance of the International Agency for Research on Cancer, the European Commission and the United States National Cancer Institute


Published: Chinese, Czech, English, Finnish, Flemish/Dutch, French German, Japanese, Korean, Portuguese, Spanish, Romanian, Turkish

Relationships with other classifications

Correspondence between revisions

Correspondence tables are available between ICD-O revisions and between ICD-O revisions and ICD-9 and ICD-10.

Correspondence with international, multinational, national classifications

The topography classification is essentially that used by ICD-10 for malignant tumours.

Relationships – conceptual, structural and other pertinent

Originally based on the American Cancer Society's Manual of Tumor Nomenclature and Coding (MOTNAC) first published in 1951.

Relationships with other terminologies

There is an agreement between the World Health Organization and the College of American Pathologists that the ICD-O morphology classification will be used for the M-8000 to M-9989 codes in the morphology axis of SNOMED. A change of SNOMED in 1993 led to incompatibilities for non-neoplastic lesions. For that reason ICD-O-3 does not longer include SNOMED codes for non-neoplastic lesions.


The Secretariat / WHO
International Association of Cancer Registries
c/o International Agency for Research on Cancer

150, cours Albert Thomas
69372 Lyon Cedex 08

Telephone: (33) 4 72 73 80 56; Fax: (33) 4 72 73 86 96

Contact information:

Mr Freddie Bray

International Agency for Research on Cancer
150, cours Albert Thomas
69372 Lyon Cedex 08
Telephone:(33) 4 72 73 80 56; Fax:Fax: (33) 4 72 73 86 96

Dr Robert Jakob

World Health Organization
20 Av. Appia
1211 Geneva 27

Page updated on 5 October 2015