Behavioural, Nutritional and Genetic Risk Factors of Colorectal Cancers in Morocco: Protocol for a Multicentre Case-Control Study

Abstract

Background: Colorectal cancer (CRC) is the third most common cancer in men and the second in women worldwide and its risk factors are complex. Genetic and environmental factors are strongly involved including lifestyle and eating habits. In Morocco, the number of new CRC cases is increasing. In parallel, cancer risk factors and behaviors of the Moroccan population are changing due to profound societal and technical changes. Aim: To that end we designed a multicenter case control study that aimed to evaluate the relationship between dietary habits, physical activity, genetics factors and the risk of CRC in Moroccan population. Methods: This case control study was conducted between January 2009 and February 2017 in 5 major University Hospital Centers in Morocco (Fez, Rabat, Oujda, Casablanca and Marrakech). Cases were matched with controls by age (±5 years), sex and center. Participants completed a face-to-face questionnaire on sociodemographic data, lifestyle, family history of CRC and no steroidal anti-inflammatory drugs. In addition, participants completed a semiquantitative food-frequency questionnaire (FFQ) was developed to assess food intake in the Morocco population. Pathology tumor samples were collected for 200 cases. For genetic data analysis, DNAs were extracted by manually scraping tissue from unstained slides. To assess the strength of the association between characteristics and the risk of CRC, odds ratios (OR) with 95% confidence intervals were estimated by conditional regression models. All statistical analyses were done using SPSS v20. Results: In total, 3032 pairs (1516 cases and 1516 controls) were recruited. Excluded participants (case/control) were unspecified primitive cancer (7 pairs), participants with missing dietary data (26 pairs) and participants with the lowest and highest 1% of the distribution of the ratio between energy intake and energy requirement (30 pairs). All together, 2906 cases and controls were recruited during the study period. Both cases and controls did not differ significantly with respect to sex 50.7% were women and 49.3% were men ( P = 0.51), the center that recruited the most was Rabat, followed by Casablanca, Oujda, Fez, and finally Marrakech ( P = 1.00). For marital status, being married was most frequent for both cases and controls (76.3% vs 77.0%) ( P = 0.36), alcohol consumption was higher in cases than controls (2.4% vs 1.7%) ( P = 0.12). However, participants in the control group were significantly more moderately active (58.4% vs 52.1%) and more likely to be never smoker (83.8% vs 77.6%). Conclusion: This study is the first large one that has described the risk factors of CRC in Morocco and in North Africa. It gives for the first time results about these risk factors which are drawn directly from this target population. Preventive recommendations could, therefore, be reviewed and adapted to these populations accordingly.