Aspirin and Delayed Chemoprevention of Colorectal Cancer

Ultra-Processed Food Intake and Risk of Colorectal Cancer: A Matched Case-Control Study

Colorectal cancer (CRC) is the third most prevalent and the second fatal cancer in the world. Ultra-processed foods (UPFs) are suggested to be related to various non-communicable diseases including cancers. However, studies on the relationship between UPFs and CRC are scarce. The aim of this study was to determine the association between consumption of UPFs and CRC. In a case-control study conducted in four hospitals in Tehran, Iran, consumption of UPFs in 71 CRC patients and 142 controls (patients with non-neoplastic diseases) were compared. Using 125-item semi-quantitative food frequency questionnaire, dietary intakes were assessed. We used Multivariate logistic regression to estimate the association between UPFs intake and risk of CRC. Intake of nondairy beverages (P = 0.009), processed meat and fast food (P = 0.04) was significantly higher in those in the highest tertile of UPFs intake compared to the lowest tertile. In addition, intake of UPFs was associated with higher risk of CRC. The association remained constant after adjustment for BMI, income, smoking, type of job, educational level, and physical activity (OR, 3.32; 95% CI, 1.44-7.61; P = 0.003). Results of this study indicate that the intake of UPFs is associated with increased odds of CRC.

Long-term use of antihypertensive medications, hypertension and colorectal cancer risk and mortality: a prospective cohort study

BACKGROUND

Hypertension and the use of antihypertensive medications have been intensively investigated in relation to colorectal cancer (CRC). Prior epidemiologic studies have not been able to examine this topic with adequate confounding control and follow-up time, or disentangle the effects of antihypertensive agents and hypertension.

METHODS

Eligible participants in the Nurses' Health Study and Health Professionals Follow-up Study were followed for up to 28 years, with repeat assessments of exposures. Cox proportional hazards models were used to estimate hazard ratios and 95% confidence intervals.

RESULTS

In fully adjusted analyses based on both new-user and prevalent-user designs, there was no association between the use of beta-blockers, calcium-channel blockers, thiazide diuretics, angiotensin-converting enzyme inhibitors, furosemide, other antihypertensive drugs and CRC risk and mortality reached the statistically significant threshold after Bonferroni correction. The results remained similar in sensitivity analyses among participants with hypertension. Before Bonferroni correction, suggestive associations between beta-blocker use and CRC risk and between furosemide use and CRC-specific mortality were observed specifically in analyses using a new-user design. Hypertension was not associated with CRC risk in analyses based on both new-user and prevalent-user designs.

CONCLUSIONS

Hypertension and long-term use of major classes of antihypertensive medications are unlikely to be associated with CRC risk and mortality.

Long-Term Statin Use, Total Cholesterol Level, and Risk of Colorectal Cancer: A Prospective Cohort Study

INTRODUCTION

Statin use has been examined as a potential chemopreventive strategy against colorectal cancer (CRC). Previous studies have not been able to investigate this topic with adequate follow-up time or disentangle the effects of statin use and total cholesterol level. We investigated prospectively this topic.

METHODS

Eligible participants (100,300 women and 47,991 men) in the Nurses' Health Study and Health Professionals Follow-Up Study were followed for up to 24 years. Cox proportional hazards models were used to estimate hazard ratios and 95% confidence intervals.

RESULTS

We documented 2,924 incident CRC cases during follow-up. In fully adjusted analyses, longer duration of statin use was associated with higher risk of colon cancer (hazard ratios, the 95% confidence interval was 1.09, 0.95-1.25 for 1-5 years; 1.16, 0.99-1.36 for 6-10 years; 1.08, 0.81-1.44 for 11-15 years; 1.85, 1.30-2.61 for >15 years; vs never users, P = 0.004 for trend) rather than rectal cancer. The risk elevation was driven by proximal colon cancer (1.16, 0.98-1.38 for 1-5 years; 1.19, 0.98-1.45 for 6-10 years; 1.25, 0.89-1.74 for 11-15 years; 2.17, 1.46-3.24 for >15 years; vs never users, P = 0.001 for trend) rather than distal colon cancer. The results remained robust in analyses among participants with hypercholesterolemia or who never received screening. Total cholesterol level was not associated with CRC risk.

DISCUSSION

This study does not support benefit of statin use in CRC chemoprevention or any association between total cholesterol level and CRC risk. On the contrary, long-term statin use may be associated with increased colon cancer risk (driven by proximal colon cancer).

Timing of Aspirin Use in Colorectal Cancer Chemoprevention: A Prospective Cohort Study

BACKGROUND

Prior epidemiological and intervention studies have not been able to separate independent effects of dose, timing, and duration of aspirin use in colorectal cancer (CRC) chemoprevention. We examined aspirin-based CRC chemoprevention according to timing in the Nurses' Health Study and Health Professionals Follow-Up Study.

METHODS

The exposures include cumulative average dose and total duration of aspirin use in more than 10 years before follow-up started (remote period) and in the immediate 10 years before follow-up started (recent period). Cox models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for exposures and CRC risk.

RESULTS

Aspirin use of longer than 10 years before follow-up started (HR = 0.88, 95% CI = 0.83 to 0.94) per 5-year increment and the immediate 10 years before follow-up started (HR = 0.90, 95% CI = 0.84 to 0.96) were similarly important in CRC chemoprevention, though a 5-year lag was required for a clear benefit in the recent period. In the remote period, the association was not dose dependent; compared with less than 0.5 standard-dose (325 mg) tablets per week; hazard ratios were 0.78 (95% CI = 0.63 to 0.98), 0.81 (95% CI = 0.72 to 0.91), and 0.74 (95% CI = 0.64 to 0.86) for doses of 0.5 to less than 1.5, 1.5 to less than 5, and 5 and more tablets per week, respectively. However, there was dose dependency in the recent period (with respective HR = 0.91, 95% CI = 0.79 to 1.06; HR = 0.87, 95% CI = 0.77 to 0.98; and HR = 0.76, 95% CI = 0.64 to 0.91).

CONCLUSIONS

A suggestive benefit necessitates at least 6-10 years and most clearly after approximately 10 years since initiation of aspirin. Remote use and use within the previous 10 years both contribute independently to decrease risk, though a lower dose may be required for a benefit with longer term use.

Updates on the molecular mechanisms of aspirin in the prevention of colorectal cancer: Review

Colorectal cancer is one of the commonest malignancies worldwide. The estimated lifetime risk of the disease is about 5% with an incidence of one million new cases and 600,000 deaths worldwide every year. It is estimated that in 2019, approximately 134,490 new cases of colorectal cancer will be diagnosed with 49,190 mortalities. Though the disease is regarded as a disorder of the more developed world, the occurrence is steadily increasing in many developing countries. Since chronic inflammation is a known aggravating risk factor for colorectal cancer, anti-inflammatory agents such as aspirin have been used to prevent the development of colorectal cancer and related mortality. The potential mechanisms for the effect of aspirin in the prevention of colorectal cancer have been proposed and broadly classified as cyclooxygenase (COX) dependent and COX-independent. Some of the primary effectors of COX-dependent mechanisms in carcinogenesis are likely to be prostaglandins. In contrast to the reversible action of other nonsteroidal anti-inflammatory drugs, aspirin is known to irreversibly inactivate COX enzymes to suppress production of prostaglandins. COX-independent mechanisms of anticancer effects of aspirin include down-regulation of nuclear factor kappa B activity and Akt activation, modulation of Bcl-2 and Bax family proteins, suppression of vascular endothelial growth factor, induction of apoptosis, disruption of DNA repair mechanisms, and induction of spermidine/spermine N¹-acetyltransferase that modulates polyamine catabolism.

Lifestyle and dietary environmental factors in colorectal cancer susceptibility

Colorectal cancer (CRC) incidence changes with time and by variations in diet and lifestyle, as evidenced historically by migrant studies and recently by extensive epidemiologic evidence. The worldwide heterogeneity in CRC incidence is strongly suggestive of etiological involvement of environmental exposures, particularly lifestyle and diet. It is established that physical inactivity, obesity and some dietary factors (red/processed meats, alcohol) are positively associated with CRC, while healthy lifestyle habits show inverse associations. Mechanistic evidence shows that lifestyle and dietary components that contribute to energy excess are linked with increased CRC via metabolic dysfunction, inflammation, oxidative stress, bacterial dysbiosis and breakdown of gut barrier integrity while the reverse is apparent for components associated with decreased risk. This chapter will review the available evidence on lifestyle and dietary factors in CRC etiology and their underlying mechanisms in CRC development. This short review will also touch upon available information on potential gene-environment interactions, molecular sub-types of CRC and anatomical sub-sites within the colorectum.