WCT EVI MAP tool

Welcome to the WCT Evidence Explorer!

This project is part of the International Collaboration for Cancer Classification and Research.

Evidence Gap Maps (EGMs)

Choose an EGM:

Download EGM

Dashboard

Level of Evidence (LOE) in the selected articles

Level of Evidence (LOE) over time in the selected articles

WCT Characteristics in the selected articles

WCT Characteristics over time in the selected articles

Download Table

Tumour type vs Level of Evidence

Tumour type vs Characteristics

Wordcloud

Build your EGM

EGM Examples:

About us

Meet the IARC team

Mr. Ramon Cierco Jimenez (developer) EVI MAP Bioinformatics Specialist and Information Assistant, WHO Classification of Tumours programme	Dr. Harshima Wijesinghe EVI MAP (IARC) Member and Visiting Scientist, WHO Classification of Tumours programme
Dr. Christine Giesen EVI MAP (IARC) Member and Visiting Scientist, WHO Classification of Tumours programme	Dr. Dr Pavitratha Puspanathan EVI MAP (IARC) Member and Visiting Scientist, WHO Classification of Tumours programme
Ms. Cécile Monnier EVI MAP Project Assistant, WHO Classification of Tumours programme	Dr Ian A. Cree EVI MAP (IARC) Member and Senior Visiting Scientist, WHO Classification of Tumours programme
Blanca Iciar Indave EVI MAP Principal Investigator, IC3R Coordinator, and Systematic Reviewer, WHO Classification of Tumours programme	Dr Dilani Lokuhetty Head, WHO Classification of Tumours programme and IC3R

Our institution

International Agency for Research on Cancer

The International Agency for Research on Cancer (IARC) is the specialized cancer agency of the World Health Organization (WHO).

The objective of the IARC is to promote international collaboration in cancer research. The Agency is inter-disciplinary, bringing together skills in epidemiology, laboratory sciences and biostatistics to identify the causes of cancer so that preventive measures may be adopted and the burden of disease and associated suffering reduced. A significant feature of the IARC is its expertise in coordinating research across countries and organizations; its independent role as an international organization facilitates this activity. The Agency has a particular interest in conducting research in low and middle-income countries through partnerships and collaborations with researchers in these regions.

Evidence Synthesis and Classification Branch

The Evidence Synthesis and Classification Branch (ESC) branch produces the WHO Classification of Tumours, the IARC Monographs on the Identification of Carcinogenic Hazards to Humans, and the IARC Handbooks of Cancer Prevention. For each volume, IARC convenes international, interdisciplinary Working Groups of expert scientists to systematically review the pertinent scientific literature and to develop consensus evaluations and classifications. IARC selects these experts based on their knowledge and experience and the absence of real or apparent conflicting interests.

Group of WHO/IARC Classification of Tumours Series

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.

Contact us

✉ WCT EVI MAP email
📍 IARC - International Agency for Research on Cancer, 25 Av. Tony Garnier, 69007 Lyon. +33 (0) 4 72 73 84 85 (Open in Google Maps)

Additional information

Name	Definition	Notes for clarification
Pathogenesis	The mechanisms – usually at the molecular and genetic level – by which a risk factor or other agent contributes to the development of a certain disease, or how the disease progresses to after its onset. Often combined studies (e.g. molecular epidemiology) using both epidemiological and laboratory methods to examine causation or pathogenesis. We include here direct studies of causation in patients, samples, cell or animal models, often using laboratory methods and also combined studies (e.g. molecular epidemiology) using both epidemiological and laboratory methods to examine causation or pathogenesis.	The pathogenesis of a disease describes the mechanisms by which it develops, progresses, and either persists or is resolved.
Diagnostic Imaging	Medical or diagnostic imaging technologies used to study the human body for the purpose of diagnosing, monitoring, or treating medical conditions. Technics include X-rays, ultrasound, computed tomography (CT) and magnetic resonance (MR), Molecular Imaging such as Single Photon Emission Computed Tomography (SPECT) and Positron Emission Tomography (PET), as well as mixed technics as SPECT/CT, PET/CT and PET/MR. These are powerful tools for the diagnosis of several health conditions, in particular cancer, allowing the visualization, characterisation and quantification of anatomical lesions or biologic events that occur at early stages of disease.	Endoscopy is not included.
Histopathology	Microscopic examination of tissue, usually with diagnostic intent, including several techniques, such as direct observation, various histologic methods and microscopic technics, including immunohistochemistry.
Cytopathology	Cytology (also known as cytopathology) is the microscopic examination of cells aspirated from tissue or obtained from bodily tissues or fluids various cytologic methods and microscopic technics, including immunocytochemistry to determine a diagnosis.
Diagnostic molecular pathology	Application of molecular tests or molecular techniques to correctly identify molecular alterations of diagnostic significance in tumours.	Laboratory methods that are used to help identify a disease or the risk of developing a disease, such as cancer, by studying molecules, such as DNA, RNA, and proteins, in a tissue or fluid sample. Molecular diagnostics may also be used to help plan treatment for a disease, look for recurrence of disease, or find out how well treatment is working. There are many types of molecular diagnostic tests, such as biomarker tests, genetic tests, tumour sequencing tests, and liquid biopsies.
Prognosis	Prognosis involves assessing the likely course and outcome of a disease once it is diagnosed regardless of the treatment applied. This domain focuses on determining the severity of the disease and predicting its future progression, which helps in planning treatment and anticipating health outcomes. Risk factors affecting progression or survival are included here.	Prognostic factors may be defined by association with a clinical outcome in the absence of therapy or with the application of a standard therapy.
Prediction	Studies evaluating the relationship between certain tumour biomarker characteristic and the expected patient’s response to a certain treatment or intervention, compared to that in the absence of this biomarker characteristic. Various factors and tests utilizing various laboratory technics can be included into this category.	Predictive factors are associated with the response to a particular therapy. They imply a differential benefit of therapy that is dependent on the value of tumour (including tumour environment) or patient related factors (Histology, TNM, Grading, Hormone Receptor Status, Molecular Characteristics, Cellular or body fluid-based biomarkers).

Name	Definition	Notes for clarification
Consensus, statements or clinical guidelines	Consensus Study: An original study which seeks a consensus among experts using a formal methodology such as a Delphi study, an online or in person survey or voting process (consensus conference) and published as a position statement/recommendation. This is distinct from simple published surveys, letters to editors or opinion articles. Clinical Practice Guidelines are defined as systematically developed statements or processes to assist clinician and patient decisions about appropriate health care for specific clinical circumstances. We will include if the abstract states ‘guideline or statement’ developed by a panel of experts or professional societies or official institutions or its abstract refers to the use of some systematic methods for the development of clinical practice guidelines or recommendations (i.e. GRADE, IOM Standards, G-I-N Standards or Guidelines 2.0).
Systematic Review	A review of the scientific evidence which applies strategies that limit bias in the assembly, critical appraisal, and synthesis of all relevant studies on the specific topic. With meta-analysis: systematic review followed by a statistical analysis of results from separate studies, examining sources of differences in results among studies, and leading to a quantitative summary of the results if the results are judged sufficiently similar or consistent to support such synthesis.	This code includes also: Umbrella Review. Umbrella Reviews or Overviews of Reviews are reviews of systematic reviews. Overviews are often broader in scope than any individual systematic review, meaning that they can examine a broad range of evidence.
Animal Study (mechanistic)	A study that uses animals or animal samples (including cell lines) as research subject including xenograft models (models of cancer where the human tissue or cells are implanted into an animal). Studies carried out in the areas of basic research (mechanistic studies) and medicine referring to human oncology. Research concerning veterinary medicine purposes are to be excluded.
Other Mechanistic Basic Science Studies	Studies without clinical data associated. In vitro/in silico studies that use human derived samples for fundamental/basic science/biological experimental work (such as living cells lines or tissues, molecules, or studies using organoids, three-dimensional miniature versions of organs or tissues generated from cells with stem potential). This does not include studies of clinical tests carried out in the lab on patient tissues taken for clinical purposes (these are considered in vivo clinical/epidemiological or diagnostic studies instead).	Are included here: In silico studies: computer simulation or evaluations of synthetic data with known properties. Molecular database derived studies: Databases from cohort or case-control consortia are considered human data (i.e., Practical, TGCA). The rest of studies using data derived from online molecular, genetic, or another biological database repository are included here.
Ecological Study	A study in which the units of analysis are populations or groups of people rather than individuals (aggregated data). Geographical comparisons with aggregated outcomes such as temporal trends including joinpoint analysis, time series, interrupted time series and correlations between aggregated variables.
Case Report	Detailed description of observations at the individual level, documented from a single patient or clinical case. This code also includes small case series with less than five subjects (n<5).
Case Series/Longitudinal Case Series	Case series: A collection of subjects (usually patients) with common characteristics used to describe some clinical, pathophysiological, or operational aspect of a disease, treatment, exposure, or diagnostic procedure. Without non-tumoral comparison group. Longitudinal case series: A single-group research design in which measurements are made at several different times, thereby allowing trends to be detected.
Population-based Descriptive Study	Population-based Descriptive Study: Studies carried out from Population-based Cancer Registries (or other population-based registries, i.e. official country mortality data) that seek to describe a population group, but without a comparison group (there may be comparisons based on sociodemographic variables such as sex, age, or ethnic groups). A hospital registry is not a population-based registry.
Diagnostic Test Agreement/Reproducibility Study	A study where the repeatability (reproducibility) of a specific diagnostic test or procedure is evaluated by multiple observers (pathologists or others) or machines (image analysis, AI), or their combination. This may take the form of a test being repeated multiple times on the same cases at different time points or, more often, where different observers (e.g., a group of pathologists) evaluate and interpret/report the results of the test independently. The results of repeated testing are compared between the observers. Sometimes diagnostic agreement/reproducibility design may accompany diagnostic accuracy studies.
Laboratory Test Validation Study	These studies validate the performance of a laboratory test or assay in a controlled laboratory environment (i.e., pathology laboratory), usually in cherry-picked cases/samples. The focus is primarily on the technical aspects of the laboratory method to ensure that it produces consistent and valid results when compared to the reference method. These studies are foundational for ensuring that a test is suitable for further clinical evaluation.
Diagnostic Test Accuracy Study	These studies evaluate the effectiveness and reliability of diagnostic tests in the clinical settings and focus on their ability to accurately detect the presence or absence of a particular disease or condition. The focus here is on the clinical utility of the test, i.e., assessing how well it helps to make accurate diagnostic decisions for a specific clinical question/situation. Therefore, the identification of selected patients and controls is mandatory as well as a comprehensive statistical analysis.	Key metrics used in these studies must include at least one of these options: The area under the curve (AUC) of the receiver operating characteristic (ROC) curve. Sensitivity, specificity, PPV, NPV: at least two of them and with 95% confidence interval (CI 95%). Sensitivity, specificity, PPV, NPV: all of them without CI 95%. These studies are designed to quantify the performance of a test in a clinical setting and inform clinicians about the reliability of the test for making diagnostic decisions.
Randomized Controlled Trial	A clinical-epidemiological experiment in which subjects are randomly allocated into groups, usually called intervention/test and control groups, to receive or not to receive a preventive or a therapeutic procedure or intervention.
Other Clinical Trial	A clinical-epidemiological experiment in which subjects are not randomly allocated into groups, to receive or not to receive a preventive or a therapeutic procedure or intervention.	Includes several types of study: Quasi-experimental: situation in which the investigator lacks full control over the allocation and/or timing of intervention but nonetheless conducts the study as if it were an experiment, allocating subjects to groups. Single-arm trials, with no control group. Historical control: The control group are subjects who were studied before the main group receive the intervention. Experimental before-after studies: An approach in which the outcome is measured before and after an intervention that has been delivered to all participants.
Observational Longitudinal Study RCT derived	The information and/or samples collected in an RCT are used to test a different hypothesis (i.e. the prognostic value of a biomarker). Patients were not randomized according to the new objective, so it is an observational study taking advantage of the systematic collection of data and the quality control measures usually included in RCTs.
Cohort study	Study design in which the investigator observes participants (free of the event that is going to be evaluated) who are exposed and unexposed and follows them up to see if they develop the disease or event of interest. In a cohort study, the investigator observes and does not assign the participants’ exposure status as in the experimental design. They could be prospective or retrospective (conducted by reconstructing data about participants at a time or times in the past).	Includes Nested Case-Control and Case-Cohort studies
Other Longitudinal Studies	Observational before-after Study: An approach in which the outcome is measured before and after an exposure has occurred to all participants. In contrast to the experimental ones, the exposure is not defined by the researcher. Other follow up studies: other longitudinal studies that do not meet the stated criteria for cohorts, they may compute percentage of survival patients or other index typical of cohort studies, but without controlling losses of follow-up and/or using survival analytical methods.
Self-matched Case-Control Study	In this design, each participant (case) serves as its own matched control. I.e., when the tumour tissue from a cancer case is compared with the corresponding “healthy” tissue from the same patient to assess the association between some characteristic/feature/exposure with the outcome (disease or cancer subtype).
Cross-Sectional Study	Study in which the outcome and other variables are determined in each participant of the study at one particular time. It can refer to a period, however observed photographically (without evolution). There is no formal selection of controls, this means that firstly the participants are recruited and only after that, they are classified depending on their diagnosis into the comparison groups (sometimes referred as cases and controls). Comparisons of histological, immunohistochemical, genetic, etc. profiles between groups of tumours are included here (exception: in this case it is considered cross-sectional even with a formal selection of controls).
Classic Case-Control Study	Study design in which the investigator selects participants with the outcome (cancer type or subtype) (cases) and a comparison group without that particular outcome (controls) to study the association between previous exposures or previous characteristics with the outcome. Cases and controls are very often matched by age, sex, or other variables.

WCT characteristics	Diagnostic imaging	Pathogenesis	Histopathology	Molecular Diagnostic Features	Prognosis	Prediction
Research focus	Clinical characteristics of the tumour	Biological development and progression	Pathological characterisation (macro- and micro-)	Molecular characterisation	Prognostics	Factors predicting response to treatment
Example questions	What is the anatomical localisation of the primary tumor? What are the signs and symptoms of the tumor? What does the tumor look like and how it interacts with surrounding tissues (X-rays, CT, MRI, PET, US)?	What are the mechanisms through which the tumour arises and progresses? What biological processes, at the cellular, molecular, or genetic levels, lead to the development and progression of the tumour?	What is the appearance of the tumour following surgical removal? What are the microscopic features, i.e. structural and cellular patterns, that indicate disease? What are the appearance and characteristics of cells aspirated from a tissue or body fluids? How well does this test confirm the diagnosis compared with a gold standard? AND / OR Is there consistency when applying the diagnostic test several times to the same subject/sample?	What biomolecules (eg. DNA, RNA, proteins, epigenetic changes) characterise cells, tissues and body fluids for the diagnosis of tumours? How well does this test confirm the diagnosis compared with a gold standard? AND / OR Is there consistency when applying the diagnostic test several times to the same subject/sample?	What is the likely course and outcome of the tumour once it is diagnosed, regardless of the treatment applied? What features influence progression or overall survival?	Does this feature/biomarker identify patients who are likely to respond to treatment?
Level 1	Systematic review	Systematic review	Systematic review	Systematic review	Systematic review	Systematic review
Level 2	Population-based descriptive study Observational longitudinal RCT-derived study Cohort study	Observational longitudinal RCT-derived study Cohort study Self-matched case-control study	Population-based descriptive study Randomized controlled trial (RCT) Observational longitudinal RCT-derived study Cross-sectional study	Population-based descriptive study Randomized controlled trial (RCT) Observational longitudinal RCT-derived study Diagnostic test accuracy study Diagnostic test agreement / reproducibility study	Population-based descriptive study Randomized controlled trial (RCT) Observational longitudinal RCT-derived study Cohort study	Randomized controlled trial (RCT) Observational longitudinal RCT-derived study Cohort study
Level 3	Classic case-control study Cross-sectional study Other cohorts & other longitudinal studies Diagnostic test accuracy study Diagnostic test agreement / reproducibility study	Classic case-control study Cross-sectional study Other cohorts & other longitudinal studies	Cohort study Classic case-control study Self-matched case-control study Diagnostic test accuracy study Diagnostic test agreement / reproducibility study	Cohort study Classic case-control study Cross-sectional study Self-matched case-control study	Non-randomized controlled trial Other cohorts & other longitudinal studies Case series / longitudinal case series	Non-randomized controlled trial Other cohorts & other longitudinal studies
Level 4	Self-matched case-control study Case series / longitudinal case series Laboratory test validation study Ecological study	Case series / longitudinal case series Other mechanistic basic science studies Animal study (mechanistic)	Other cohorts & other longitudinal studies Case series / longitudinal case series Laboratory test validation study	Other cohorts & other longitudinal studies Case series / longitudinal case series Laboratory test validation study	Cross-sectional study Classic case-control study Ecological study	Cross-sectional study Classic case-control study Case series / longitudinal case series Ecological study
Level 5	Case report	Case report	Case report	Case report	Case report	Case report
Unclassifiable	Big picture reviews Consensus, statements, or clinical guidelines, & other study designs not included in cells above	Big picture reviews Consensus, statements, or clinical guidelines, & other study designs not included in cells above	Big picture reviews Consensus, statements, or clinical guidelines, & other study designs not included in cells above	Big picture reviews Consensus, statements, or clinical guidelines, & other study designs not included in cells above	Big picture reviews Consensus, statements, or clinical guidelines, & other study designs not included in cells above	Big picture reviews Consensus, statements, or clinical guidelines, & other study designs not included in cells above