In this section we aim to discuss the main features of the methodological design of Prevencanadol:
Firstly, the project complies with the basic requirements for a parallel randomized controlled trial: (a) the study factor is artificially manipulated (online educational intervention and delivery of SMS) and (b) the study population is randomly distributed to an EG and to a CG. Notwithstanding that, this randomization is determined by the first registered student of a classroom, and consequently real classroom randomization is achieved. From this standpoint, this trial can be considered a cluster randomized controlled trial, which is a very useful design to avoid the possible contamination of the groups. However, an important limitation of the experimentation with educational interventions is that it is not possible to guarantee that participants have received the content of the intervention, as it could be done if it were a pill, for instance. But Prevencanadol has managed to reduce this limitation since it has incorporated in the statistical analysis the scoring obtained during the competition, which is an indirect indicator of the reception degree of the intervention.
Secondly, as already pointed out, the program addresses a target population between 12 and 16 years old in order to reach the highest cancer preventive efficacy, since adolescence is a vital stage in which many behaviors (that will shape the adult stage) are acquired and consolidated. Although it can be a difficult age range, prevention of risk behaviors in this population group is also possible, especially if advice is linked to the school context [32–34]. However, it is not a task that is exclusively linked to school: we should bear in mind that society and family can be important sources of behaviors , and therefore we also encourage the registering of adults (teachers and family) in the website http://www.alertagrumete.com. In this way, it is even possible that healthy adolescents also become instigators of some preventive behaviors among adults; that consequently achieves ascending education. Finally, regarding the diversity of participants, we should also mention that we could only have included in the program adolescents with established risk behaviors, as other authors do in their works , but in our opinion when working with such a young population, it is as necessary to treat existing risk behaviors as well as to prevent their presence.
Thirdly, as the intervention is both school- and web-based, it is required that adolescent participants are currently attending school and have Internet access available. In relation to the first requirement, we can affirm that about 5.4% and 13.2% of the Spanish and Mexican adolescents respectively do not regularly attend school , usually because they belong to disadvantaged environments. Regarding the second condition, we can conclude that in Spain almost all schools have Internet access , but in Mexico only less than half comply with this requirement . Due to these two reasons, the intervention could be confined only to those families and schools with a higher socioeconomic level.
Fourthly, the chosen educational tools (Internet and SMS) are novel in the field of Health Education and can be easily adapted to young population. In addition, students and teachers of Secondary Education helped with the web design in order to avoid the refusal of the participating students, since it is well-known that planning this kind of interventions without bearing in mind the likes of the target population could cause them to fail even before they have been implemented . However, the vertiginous evolution of this kind of technologies may have clouded the originality of this initiative, since nowadays global social networks (such as Facebook, Twitter, Ozone, etc.) have completely changed the way in which the web is understood. It might have even caused a certain lack of interest in the users towards other kinds of websites or minority social networks, as this one we have tried to create through http://www.alertagrumete.com.
Lastly, we would like to mention that Catalano et al.  published in 2012 an interesting manuscript that seems to support the approach of Prevencanadol since: (a) they acknowledge it is necessary to involve state workers (in this case, teachers) in the program; (b) these authors also suggest the identifying of both the problems and the groups in which an educational intervention is urgently needed (this is one of the aims of Prevencanadol, which we have highlighted above); and specially (c) they highlight that it is necessary to prove the efficacy of these initiatives in lower-middle income countries, as well as to find factors in these countries that can be different to those found in richer countries (and that is exactly what this program has done in Mexico).
To sum up, Prevencanadol could be considered groundbreaking, since it (a) aims to link family and school environments, (b) combines the use of the Internet and the delivery of SMS, (c) considers psychosocial models which are supported internationally, (d) intervenes in six behaviors simultaneously, and (e) compares the efficacy of the intervention in a country with a high income level (Spain) with that obtained in another one with a middle income level (Mexico).