RESUMEN
BACKGROUND: Current communication technologies can be used in health education. The aim was to assess the process of an online program designed to prevent cancer risk behaviours using an educational website and mobile phones. METHODS: High school students from Spain and Mexico were recruited during 3 academic years (2009-12) to participate in a web-based program supplemented with mobile phone messages (SMS) which aim was to prevent cancer risk behaviours. The program was designed as a randomized trial, with control and experimental group (EG). Recruitment and adherence were analyzed using data of the Web management platform and Google Analytics. RESULTS: 3,855 students started the logging on the program of which 2,001 (51.9%) completed the questionnaire.77.5% were Mexicans, 13 years old (40.6%), with good academic level (68.7%) and with parents (49.6%) and mothers (53.9%) having university degree. 56.4% recorded a phone number to receive SMS. The EG consisted of 1,014 students and the averages of their visits to the website were 31.6 in the first year, 21.8 in the second and 21.9 in the third. Each adolescent of the EG was able to incorporate 1.16 adults (total 1,172) and other 1,076 were recorded spontaneously. Retention rate at the end of follow-up was 41.5% and was higher among those who were best students (OR: 12,5), Mexicans (OR: 4.4), 12 years old (OR: 3.1) and have been incorporated in the first three months of the implementation (OR: 2.8). CONCLUSION: Students' recruitment and retention was scarce, mainly in Spain. However students involved visited the program website with sufficient amount of time to achieve good results.