You cannot improve what you cannot measure. In cancer care, that principle has a very concrete meaning: without reliable, population-level data on who is diagnosed with what cancer, at what stage, where, and with what outcomes, health systems are essentially navigating blind. In turn, policy and health decisions are made on incomplete pictures. Resources go where they are assumed to be needed rather than where the evidence points. Patients fall through the cracks and no one can see it.
This is exactly the problem City Cancer Challenge (C/Can) and its partners in León, Mexico have been working to solve through the Information Systems and Data project.
Since 2024, C/Can and its partners have been strengthening the foundations of a population-based cancer registry in León, building on the city’s own efforts to establish its registry, which began in 2019. This activity requires coordinating various stakeholders from public and private institutions across Mexico’s fragmented health system, aligning institutions that have historically operated in silos, and establishing the data collection processes and infrastructure necessary to create a comprehensive and operational registry. Without it, León, and Mexico, cannot fully understand its cancer burden, let alone respond to it effectively.
A National Commitment, Formalised
In September 2025, the project in León reached a significant milestone. As part of Mexico’s broader national efforts to establish a network of population-based cancer registries, coordinated by INCan since 2016, INCan (the National Cancer Institute of Mexico), the Secretary of Health of Guanajuato, and IMSS (the Mexican Institute of Social Security) signed a formal collaboration agreement to implement and operate a population-based registry for the central region of the state of Guanajuato, covering the municipalities of León, Silao, Purísima del Rincón, and San Francisco del Rincón, with C/Can as a witness of honor. The signing, held at INCan, also marked a broader technical cooperation agreement between INCan and C/Can, cementing the commitment to coordinated action on cancer prevention, diagnosis, and treatment across Mexico.
Today’s agreement with City Cancer Challenge represents an effort to implement all of our cancer care programmes jointly. It is essential that this implementation reaches the population and that we have a prototype city, in this case León, to serve as an example, as a public health policy model for all cities and states: to understand what works and what does not in our country, and where our gaps lie. Beyond improving care in the state of Guanajuato, we need this information to help us improve care across the entire country. And above all, we now have formalised, with the state, the support we need for the national population-based cancer registry to strengthen it, improve its quality, and generate the incidence and mortality rates and trends that will allow us to make the right decisions and public policies for Mexico.
Dr Oscar Gerardo Arrieta Rodriguez, Director General, INCan.
The alliance between C/Can, IMSS, and INCAN has been very important for the launch and implementation of the Population-based Registry Leon Bajio. Nowadays, the registry is the phase of increased coverage and exhaustivity. The City Cancer Challenge collaboration will permit the improvement of the consolidation and establishment of the registry.”
Dr Yelda Aurora Leal Herrera, Director, Centro Institucional del Registro de Cáncer de Base Poblacional, IMSS-INCan.
C/Can Leads Expert Mission to León with The International Agency for Research on Cancer (IARC)
From 17-20 March 2026, C/Can led an expert mission to León to conduct a formal review of the registry, bringing in IARC as a technical partner. IARC’s involvement reflects León’s ambition to ensure its registry meets international standards.
The team assessed how the cancer registry was functioning on the ground: what data sources are contributing, how data are collected, what data quality processes are in place, and whether they meet international standards. Evaluating coverage, analysing data quality, and identifying gaps were all part of this review, alongside the preparation of a report with concrete recommendations to strengthen what already exists.
The Leon population-based cancer registry is advancing in a solid way with a motivated team gathering data from major institutions. Moving forward, the goal is to bring in more partners and collaborators so the registry can achieve the coverage it needs. Visiting the León PBCR has been a really enriching experience, bringing together C/Can, IARC -GICR, the National Cancer Registry of Mexico, and the León Cancer Registry.
Dr Marion Piñeros, Section of Cancer Surveillance, International Agency for Research on Cancer
On 19 March, a roundtable was held at Hospital Aranda de la Parra to open the conversation beyond the institutions already involved. The event brought together clinicians, administrators, and health authorities from across the city to make the case that joining the registry is a contribution to something genuinely consequential. Every institution that captures cancer diagnoses and is not yet participating into the registry represents a blind spot in the data. Closing those gaps is how León, and ultimately Mexico, builds the evidence base necessary to drive real improvements in cancer care.
Making every Case Count
For C/Can, the expert mission represents a broader principle that runs through all of its work in León: that sustainable improvements in cancer care require not just clinical solutions, but the systems, data, and institutional alignment to support them. A registry that can produce comparable, complete, accurate, timely and precise data is a foundation that will outlast any single project or partnership.
The visit by IARC experts has improved the quality of the data in León’s population-based cancer registry; these international guidelines will enhance the registry’s validity, fostering confidence in multi-institutional participation and accurately reflecting the city’s ecosystem.
Dr Blanca Olivia Murillo Ortiz, Coordinator of the Population-Based Cancer Registry of Leon and Metropolitan area, IMSS.
The IARC expert mission is a quality check and a call to action, for León, Guanajuato, and for the national cancer data infrastructure that Mexico needs to make every case count.
