Differences between men and women with respect to colorectal cancer mortality despite screening colonoscopy

Causal Relationships between Polyunsaturated Fatty Acids and Colon Polyps: A Two-Sample Mendelian Randomization Study

BACKGROUND

Epidemiological studies have shown that fatty acids, especially polyunsaturated fatty acids (PUFAs), influence colorectal carcinogenesis. Colon polyps, particularly those identified as precancerous, are a frequently encountered phenomenon associated with PUFAs. However, the results are inconsistent. Therefore, we investigated the effect of PUFAs on colon polyps in individuals of European ancestry.

METHODS

Single nucleotide polymorphisms correlating with PUFAs and colon polyps were derived from extensive genome-wide association studies, encompassing a discovery cohort of 135,006 samples and a corresponding validation set with 114,999 samples. Causality was assessed by employing a range of techniques, such as inverse variance weighted (IVW), weighted median, MR-Egger, and simple and weighted modes. The analysis was complemented with sensitivity checks using leave-one-out and heterogeneity evaluation through MR-IVW and Cochran's Q.

RESULTS

A thorough analysis was performed to examine the causal effects of PUFAs on the development of colon polyps. The findings indicated that levels of Omega-3 fatty acids (OR = 1.0014, 95% CI 1.0004-1.0024, p = 0.004), the ratio of Docosahexaenoic acid (DHA)/total fatty acids (FAs) (DHA/totalFA; OR = 1.0015, 95% CI 1.0002-1.0028, p = 0.023), and the ratio of Omega-3/totalFA (Omega-3/totalFA; OR = 1.0013, 95% CI 1.0003-1.0022, p = 0.010) were identified as biomarkers associated with an increased risk of colon polyps. Conversely, the ratio of Omega-6/Omega-3 (OR = 0.9986, 95% CI 0.9976-0.9995, p = 0.003) and the ratio of Linoleic acid (LA)/totalFA (LA/totalFA; OR = 0.9981, 95% CI 0.9962-0.9999, p = 0.044) were negatively associated with susceptibility to colon polyps. The MR-Egger and MR-IVW analysis revealed that pleiotropy and heterogeneity did not significantly impact the outcomes.

CONCLUSION

This study has uncovered a possible adverse effect of PUFAs, notably Omega-3, on the formation of colon polyps. Elevated Omega-3 levels were correlated with a heightened risk of colon polyps.

Gender Differences in Quality of Bowel Preparation for Colonoscopy: Post Hoc Analysis of a Randomized Controlled Trial

OBJECTIVE

Bowel cleansing is a key element for a quality colonoscopy. Despite recent advances, not all predictors of successful cleansing are fully known. This post hoc analysis of an RCT aims to explore gender differences in bowel cleansing quality.

METHODS

The "OVER" trial was a multicenter phase-4 RCT including 478 patients randomized 1:1 to receive split-dose 1L polyethylene glycol plus ascorbate (PEG+ASC) or 4L-PEG. In this post hoc analysis, multivariable logistic regression models were designed to assess predictors of cleansing success (CS) and adenoma detection rate (ADR) by gender.

RESULTS

Of the 478 randomized patients, 50.2% were males and 49.8% females.Overall, CS was comparable between females and males (87.1% vs 88.4, P = 0.6), whereas CS in the right (95.7% vs 90.9, P = 0.049) and transverse colon (98.6% vs 93.9, P=0.011) was significantly higher in females.At multivariable regression analysis for CS outpatient setting (OR = 5.558) and higher withdrawal time (OR = 1.294) were independently associated with CS in females, whereas screening/surveillance indication (OR = 6.776) was independently associated with CS in males.At multivariable regression analysis for ADR, running time <5 hours (OR = 3.014) and higher withdrawal time (OR = 1.250) were independently associated with ADR in females, whereas older age (OR = 1.040) and higher withdrawal time (OR = 1.093) were independently associated with ADR in males.

CONCLUSIONS

This study showed different results in bowel preparation quality and different predictors of CS and ADR by gender. These findings suggest the need for further research to explore gender-specific approaches for bowel preparation.