Background
Evidence-based practice has substantially advanced cancer pathology, research, and tumour classification. However, systematically identifying high-quality evidence and clearly characterizing evidence gaps remains a challenge for both researchers and clinicians.
Objective
To develop a software tool that allows to explore evidence gap maps (EGMs) of scientific literature to support evidence-based decision-making in tumour classification and facilitate identification of knowledge gaps and pockets of low-level evidence to inform future research priorities and health policies in the field.
Methods 
We developed an intuitive web application that integrates EGMs in a searchable database of scientific evidence related to tumour classification. The application is built entirely on open-source technologies. The user interface was implemented using R Shiny (R v4.3.3; Shiny v1.8.1.1), while the backend database prototype uses MariaDB (v10.4.32), a MySQL-compatible relational database. Both components were optimized to support dynamic querying and responsive interaction, enabling efficient exploration of complex evidence structures.
Results 
The application consists of three main components to enable the end-user to perform a focused exploration of specific areas within the retrieved evidence:

1. EGM Panel: Users can explore evidence gap maps with functionality analogous to EPPI-Mapper, enabling structured visualization of the available evidence across tumour types and pathology domains.
2. Dashboard: Users can filter and query articles based on tumour type, pathological characteristics, and level of evidence, among other criteria, allowing targeted exploration of specific classification questions. Interactive visualizations complement the filtered results to support rapid interpretation.
3. EGM Creator Panel: Users can generate customized EGMs by selecting tumour entities and classification features of interest, drawing directly from the underlying evidence database.The resulting web application, the WCT Evidence Explorer, provides a practical decision-making support tool for decision making in topics related to tumour classification and cancer research.

Conclusions
By combining evidence gap maps with a structured, searchable evidence base, the WCT Evidence Explorer streamlines the identification of research gaps and improves access to relevant, high-quality evidence. The platform supports more transparent and systematic use of evidence in tumour classification, with potential benefits for both policy makers, pathologists, researchers and clinicians.