Hypothesis and data-driven dietary patterns and colorectal Cancer survival: findings from Newfoundland and Labrador colorectal Cancer cohort

BACKGROUND: Dietary patterns are commonly used in epidemiological research, yet there have been few studies assessing if and how research results may vary across dietary patterns. This study aimed to estimate the risk of mortality/recurrence/metastasis using different dietary patterns and comparison amongst the patterns. METHODS: Dietary patterns were identified by Cluster Analysis (CA), Principal Component Analysis (PCA), Alternate Mediterranean Diet score (altMED), Recommended Food Score (RFS) and Dietary Inflammatory Index (DII) scores using a 169-item food frequency questionnaire. Five hundred thirty-two colorectal cancer patients diagnosed between 1999 and 2003 in Newfoundland were followed-up until 2010. Overall Mortality (OM) and combined Mortality, Recurrence or Metastasis (cMRM) were identified. Comparisons were made with adjusted Cox proportional Hazards Ratios (HRs), correlation coefficients and the distributions of individuals in defined clusters by quartiles of factor and index scores. RESULTS: One hundred and seventy cases died from all causes and 29 had a cancer recurrence/metastasis during follow-up. Processed meats as classified by PCA (HR 1.82; 95% confidence interval (CI) 1.07–3.09), clusters characterized by meat and dairy products (HR 2.19; 95% CI 1.03–4.67) and total grains, sugar, soft drinks (HR 1.95; 95% CI 1.13–3.37) were associated with a higher risk of cMRM. Poor adherence to AltMED increased the risk of all-cause OM (HR 1.62; 95% CI 1.04–2.56). Prudent vegetable, high sugar pattern, RFS and DII had no significant association with both OM and cMRM. CONCLUSION: Estimation of OM and cMRM varied across dietary patterns which is attributed to the differences in the foundation of each pattern. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s12937-018-0362-x) contains supplementary material, which is available to authorized users.