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Section of Evidence Synthesis and Classification

WHO Classification of Tumours Group


Cancer classification has previously been based on consensus histopathological opinion, with limited molecular input. However, the understanding of cancer is currently undergoing a more rapid transformation than at any time during the past 30 years, as a result of the introduction of new technologies to practice. The molecular knowledge of cancer is now at a point where it needs to be integrated into cancer diagnosis. Digital pathology and imaging are now also producing new insights, and providing justification of many existing diagnostic criteria while challenging others. Rapidly improving computer technology, including artificial intelligence, is already producing clinically applicable aids to diagnosis, and this trend is likely to accelerate. There is an urgent need to integrate these facets of diagnosis into a globally accepted cancer classification.

The WHO Classification of Tumours series (also known as the WHO Blue Books) provides an evidence-based classification of all cancer types, to enable diagnosis and research worldwide.

Pathologists and others in the cancer community need timely synthesis and evaluation for tumour classification based on expert consensus review of peer-reviewed published evidence. The definitions are incorporated into the International Classification of Diseases (ICD) codes. The WHO Blue Books provide the user with a unique synthesis of clinical, imaging, histopathological, and molecular standards to guide cancer diagnosis. The diagnosis and classification of individual cancers underpins treatment of individual patients, as well as research into all aspects of cancer causation, prevention, therapy, and education.

The WHO Blue Books contribute to the Agency′s mission of monitoring global cancer occurrence, since without clearly defined histopathological and genetic diagnostic criteria, epidemiological and clinical studies are difficult to conduct.

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