Evidence and Gap Maps (EGMs)

An evidence and gap map (EGM) is a systematic presentation of all relevant evidence about a specific topic or research question. EGMs provide a visual and interactive display to explore the amount and/or the level of evidence of the studies by study design, and in turn to identify gaps where evidence is missing and pockets of low-level evidence. EGMs provide a foundational source of information on which to base future research.

The IARC Handbooks of Cancer Prevention programme has developed EGMs based on the systematic reviews performed for IARC Handbooks Volume 19: Oral Cancer Prevention, which summarizes all the available evidence related to primary and secondary prevention of oral cancer.

The EGM framework is presented as a matrix. The rows represent interventions, such as preventive dietary agents, interventions for cessation of smokeless tobacco and/or areca nut use, and determinants of participation in screening for oral cancer. The columns represent outcomes, such as oral cancer incidence and mortality, cessation (quit) rates for smokeless tobacco and/or areca nut use, and screening participation percentage. At the intersection of a row and a column, bubbles indicate the number of studies (size) and the study design (colour). General and specific filters can be applied to selectively display the studies for the chosen filtering variable.

The following EGMs are available:

• Primary Prevention Intervention: Preventive dietary agents – evidence on the protective effects of consuming dietary agents on the incidence of oral cancer and oral potentially malignant disorders (OPMDs)
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• Primary Prevention Intervention: Quitting exposure to oral cancer risk factors – evidence on the potential protective effect of quitting exposure to a risk factor on the incidence of oral cancer and oral potentially malignant disorders (OPMDs), and on oral cancer mortality
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• Primary Prevention Intervention: Interventions for cessation of smokeless tobacco and areca nut use – evidence on the effectiveness of behavioural interventions alone, pharmacological interventions alone, and combined pharmacological and behavioural interventions on cessation of smokeless tobacco and areca nut use
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• Primary Prevention Intervention: Policies for smokeless tobacco and areca nut control – key evidence on the implementation and/or impact of implementation of policies for smokeless tobacco and areca nut control
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• Secondary Prevention Intervention: Screening – evidence on the effectiveness of screening by clinical oral examination on the incidence of oral cancer and oral potentially malignant disorders (OPMDs), and on oral cancer mortality; evidence on factors that determine participation in oral cancer screening; interventions to increase participation in oral cancer screening
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EGM navigation guide

The coding tool used to develop the EGMs is available on the EPPI Visualiser tool, which can be used to generate various visualization items on selected variables, such as tables, bar graphs, pie charts, and even more EGMs: https://eppi.ioe.ac.uk/eppi-vis/login/open?webdbid=775