Dietary patterns and the adenomacarcinoma sequence of colorectal cancer.

BACKGROUND: Food components of a diet are highly related, so that building up dietary patterns may help understand the relationship between chronic diseases and diet, and identify high risk groups that need preventive advice. AIM: The aim of this study was to determine dietary patterns associated with the colorectal adenoma-carcinoma pathway. METHODS: We performed a two-step analysis using first principal component analysis to select the most appropriate food groups, then a hierarchical agglomerative clustering method, in order to determine dietary patterns in 1372 subjects included in a case-control study. Patients with hyperplastic polyps (n = 103), adenomas < 10 mm, (n = 154) or larger adenomas (n = 208) were then compared with polyp-free controls (n = 426), and colorectal cancer cases (n = 171) compared with population controls (n = 309) using unconditional logistic regression adjusted on age and gender. RESULTS: Cluster analysis determined five food patterns. Cluster 1 identified a low-energy diet; cluster 2 a high-starch, highfat, and low-fruit diet; cluster 3 a high-processed meat, -energy, -alcohol, and -starchy foods diet; cluster 4 a high-fish, -cereals, -honey, -olive oil, -fruit and -vegetables diet; and cluster 5 a high-flour, -sugar, -chocolate, -animal fats, and -eggs diet. Logistic regression identified cluster 2 [corrected] as significantly associated with risk of small adenomas (OR = 1.7; 95% confidence interval 1.0-2.7), large adenomas (OR = 1.9; 1.2-3.0) and cancers (OR = 1.7; 1.1-2.8) compared with cluster 1 [corrected] Cluster 4 diet was inversely associated with risk of small adenomas (OR = 0.4; 0.2-1.0). There was no relationship between patterns and risk of hyperplastic polyps. Multiple adjustment decreased the strength of the relationships with cluster 2 [corrected] which remained significantly associated with adenomas, but not cancer. CONCLUSION: A lowenergy diet appeared as protective all along the adenoma-carcinoma sequence, contrary to a high-energy, high-processed meat and -animal fat diet.