The EPIC cohort includes over 520,000 individuals who were recruited between 1992 and 2000 from 23 study centers across 10 European countries (Denmark, France, Germany, Greece, Italy, Norway, Spain, Sweden, the Netherlands, and the UK). Participants were 35-70 years of age at recruitment, and approximately 70% of the cohort are women. The study design has been previously described [22 (
link), 23 (
link)]. In brief, extensive questionnaire data on dietary and lifestyle variables were collected at baseline, and approximately 75% of individuals provided non-fasting blood samples.
Incident cases of colorectal cancer were identified through record linkage with regional cancer registries or via a combination of methods, such as the use of health insurance records, contacts with cancer and pathology registries, and active follow-up through participants and their next of kin. Colorectal cancer was defined using the tenth edition of the International Classification of Disease (ICD-10) and the second edition of the International Classification of Disease for Oncology (ICD-O-2). Proximal colon cancers included those found within the cecum, ascending colon, hepatic flexure, transverse colon, and splenic flexure (C18.0 and C18.2–18.5). Distal colon cancers included those found within the descending (C18.6) and sigmoid (C18.7) colon. Overlapping (C18.8) and unspecified (C18.9) lesions of the colon were classed as colon cancers only. Cancer of the rectum included cancers occurring at the recto-sigmoid junction (C19) and rectum (C20).
The current study employed a fasted subset of EPIC data, obtained from two separate metabolomics studies on colorectal cancer, as a discovery cohort. Samples were analyzed using the Biocrates AbsoluteIDQ
TM p180 kit (467 cases and 467 matched controls) and the p150 kit (1141 cases and 1141 controls). Combining these studies and then excluding non-fasting participants resulted in a final combined sample of 654 fasted cases and 654 controls, of which 354 case-control pairs were analyzed using the p180 kit. Controls were selected using incidence density sampling from all cohort members who were alive and free of cancer (except non-melanoma skin cancer) at the time of diagnosis of the colorectal cancer cases. Controls were matched to cases on age at recruitment (within 6 months), sex, study center, follow-up time since blood collection, time of day at blood collection (within 4 h), and fasting status. Women were further matched on menopausal status (pre-, peri-, and post-menopausal) and, in pre-menopausal women, phase of menstrual cycle at blood collection. Approval for the study was obtained from the International Agency for Research on Cancer (IARC) and local center review boards. All participants provided written informed consent.
Rothwell J.A., Bešević J., Dimou N., Breeur M., Murphy N., Jenab M., Wedekind R., Viallon V., Ferrari P., Achaintre D., Gicquiau A., Rinaldi S., Scalbert A., Huybrechts I., Prehn C., Adamski J., Cross A.J., Keun H., Chadeau-Hyam M., Boutron-Ruault M.C., Overvad K., Dahm C.C., Nøst T.H., Sandanger T.M., Skeie G., Zamora-Ros R., Tsilidis K.K., Eichelmann F., Schulze M.B., van Guelpen B., Vidman L., Sánchez M.J., Amiano P., Ardanaz E., Smith-Byrne K., Travis R., Katzke V., Kaaks R., Derksen J.W., Colorado-Yohar S., Tumino R., Bueno-de-Mesquita B., Vineis P., Palli D., Pasanisi F., Eriksen A.K., Tjønneland A., Severi G, & Gunter M.J. (2023). Circulating amino acid levels and colorectal cancer risk in the European Prospective Investigation into Cancer and Nutrition and UK Biobank cohorts. BMC Medicine, 21, 80.