A prospective study of erythrocyte polyunsaturated fatty acids and risk of colorectal serrated polyps and conventional adenomas.

The influence of polyunsaturated fatty acids (PUFAs) on risk of colorectal cancer precursors remains largely unknown. We examined the associations of erythrocyte PUFAs, including n−3 and n−6 PUFAs, with risk of colorectal conventional adenomas and serrated polyps in 4517 participants from three US prospective cohorts who had provided a blood sample and undergone at least one endoscopic examination. We calculated the multivariable odds ratios (ORs) per 1 SD increment in individual PUFAs and the ratio of n−6/n−3 PUFAs. We considered P <.005 statistically significant to account for multiple testing. During a median of 20 years of follow‐up, we documented 493 conventional adenomas and 316 serrated polyps. After adjusting for various CRC risk factors, no associations for PUFAs achieved the stringent statistical significance for either conventional adenomas or serrated polyps (ORs per 1 SD ranged from 0.90 to 1.14). Some associations achieved nominal significance (P <.05), including the association of dihomogammalinolenic acid (DGLA) (20:3, n−6) with lower risk of conventional adenomas (OR = 0.91; 95% confidence interval [CI] = 0.83‐1.00), total n−6 PUFAs with higher risk of proximal serrated polyps (OR = 1.32; 95% CI = 1.01‐1.74) and eicosadienoic acid (20:2, n−6) and DGLA with lower risk of advanced adenomas (OR = 0.83; 95% CI = 0.71‐0.97 and OR = 0.84; 95% CI = 0.72‐0.98, respectively). Our findings indicate that erythrocyte PUFAs in a typical American diet are unlikely to have a substantial influence on risk of colorectal cancer precursors. The subgroup associations require further confirmation. What's new? The influence of polyunsaturated fatty acids on risk of colorectal cancer precursors remains largely unknown. Over a median follow‐up duration of 20 years, this prospective study examined the associations of erythrocyte n‐3 and n‐6 polyunsaturated fatty acids with risk of colorectal cancer precursors in three large prospective cohorts in the United States. No statistically significant association was found at α=0.005 level for any of the fatty acids with either conventional adenomas or serrated polyps. The findings indicate that n‐3 and n‐6 polyunsaturated fatty acids in a typical American diet are unlikely to have a substantial impact on colorectal cancer precursors. [ABSTRACT FROM AUTHOR]