Background
Since 1975, Jalisco state, located in the central-western region of Mexico, began implementing a histopathology-based cancer registry through the Public Health Services Coordination and the National Campaign Against Cancer, utilizing the pathology laboratories network of both public and private sectors. During the following decades, the cancer registry participated in two national initiatives: first with the National Cancer Registry (1982) and second with RHNM (1994). However, it closed in 2014. By 2017, the registry was reopened with the support of INCan and the RedCancerMx initiative to attempt to implement a population-based registry covering Guadalajara City and its metropolitan area. Unfortunately, it closed again in 2020. In 2023, the Jalisco Ministry of Health established a new institutional framework via Decree-29146/LXIII/23. Finally, at the end of 2023, it was included in the national Population-Based Cancer Registry (PBCR) network, adopting the International Agency for Research on Cancer (IARC) guidelines and quality criteria, and focusing efforts on achieving population coverage in a short time.
Objectives
To provide a brief overview of key aspects of the PBCR establishment in Guadalajara city and describe the pre­liminary results achieved for the years 2017-2024.
Methods
The population covered by the PBCR includes 1,385,629 inhabitants within a 151 km² area of Guadalajara city, the capital of Jalisco state, that concentrates oncological services in the region. Database from 2017-2020 was incomplete and non-standardized. Subsequent efforts focused on enhancing quality control, standardizing core variables, refining data capture procedures, and developing an Information Sources Matrix (comprising 95 establishments). Additionally, there was an expansion of coverage and an improvement in the skills of registry teams in accordance with IARC guidelines. CanReg5 software was used for data entry, storage, and analysis. 
 Results
A total of 10,282 new cases were collected using both active and passive methods from 72.2% of the information sources, with the majority occurring among females at 61.2%. The most frequent cancers among females were breast cancer at 39.5%, colorectal cancer at 7.3%, cervical cancer at 6.6%, ovarian cancer at 6.2%, and corpus uteri cancer at 5.7%. In contrast, among males, it was prostate cancer at 24.6%, colorectal cancer at 12.9%, lymphomas at 8.1%, lung cancer at 5.8%, and kidney cancer at 4.3%. Childhood and adolescent cancers (0-19 years) represent 2.1% of all cancers, with leukemias accounting for 23.9%. Regarding data quality, 86.4% of the cases have morphological verification, and 3.0% are DCO. Age-adjusted cancer incidence rates per 100,000 for all sites were 78.3 for females and 56.6 for males.
Conclusions / Implications
The implementation of the Guadalajara-PBCR has been a sustained effort over several years. It will be the second population registry with successful approach in Mexico. The preliminary results provide a critical baseline for understanding the cancer burden in the region. Therefore, it is necessary to continue with both local and national efforts to achieve consolidation and obtain high-quality cancer data to inform public health policies and cancer control strategies.