Establishing a cancer cohort in Latin America: The Mexican Teachers Cohort

Abstract

Purpose In Latin America, prospective cancer research is restricted by limited access to cancer outcome data. In this study, we demonstrate a strategy for identifying incident breast cancer cases within an established prospective cohort, the Mexican Teachers’ Cohort (MTC), through the use of self-reports, electronic health records (EHRs), administrative databases, and registries. Methods The MTC consists of 115,275 female teachers aged 25 years and older who completed a questionnaire on reproductive history, lifestyle, and health between 2006 and 2008. We used self-reported breast cancer, mortality and cancer registries, and EHRs and administrative databases for case ascertainment. Person-time was calculated from the date of baseline questionnaire response to diagnosis, death, or December 31, 2019. We estimated age-specific and age-standardized incidence rates for breast cancer. Results We identified 1,313 incident breast cancers; 94% were confirmed through registries and/or databases, and 6% directly by contacting participants. The crude breast cancer incidence was 102 per 100,000 person-years, with the highest incidence in women aged 65–69 (185 per 100,000 person-years). The age-standardized incidence was 77 per 100,000. Over one-third of cases (n = 476) occurred in women younger than 50 years. Conclusion The efficient identification of participants with incident breast cancer in the MTC demonstrates that prospective cancer cohorts can be successfully established in Latin America.