Design: an international, multicenter, retrospective case-control study of prospectively enrolled patients; low-risk intervention study as it will perform a fecal occult blood test Endpoint: predictive power of a semi-quantitative food frequency questionnaire (SQFFQ) developed for eoCRC. Cases: Patients with a recent diagnosis of eoCRC (within 2 years from enrollment). Controls: matched by age (matching range ± 5 years) and sex. Healthy volunteers will be mainly enrolled among workers within the participating hospital center. The enrolled healthy volunteers will perform a fecal occult blood test. Variables of interest: age, sex, ethnicity, BMI at the time of eoCRC diagnosis and at 18 years old, country, tobacco smoking at the time of eoCRC diagnosis and at 18 years old, sitting time, TV-viewing time, moderate-to-vigorous physical activity (MVPA), waist circumference (cm), home blood pressure levels (mmHg), fasting blood glucose (mg/dl), regular consumption of aspirin/NSAID, calcium and folate supplements, oral contraceptive agents, post-menopausal hormones and years of consumptions, if the filled questionnaire reflects diet for the last 5-10 years before. Cases only: date of eoCRC diagnosis, symptoms at diagnosis, eoCRC localization, eoCRC stage, histological diagnosis, type of surgery, and date (if performed), chemotherapy and radiotherapy (if performed), vital status and duration of follow-up, family history of CRC and other cancers (uterus, ovary, stomach, small intestine, urinary tract/bladder/kidney, bile ducts, brain, pancreas, skin tumors), type of germline pathogenetic variant (if performed). Before the case-control study, three non-consecutive 24-hour Dietary Recalls (24hDRs) will validate the SQFFQ. The SQFFQ will be administered to the validation study group during three non-consecutive calls, including one non-weekday (30-minute 24-h-recall computer-aided personal interview). Primary Objective To measure the relative risk of specific dietary and lifestyle factors (smoking habit, alcohol intake, physical activity) for early-onset colorectal cancer in countries where eoCRC incidence is increasing versus stable/decreasing