The Effect of Low Doses of Acetylsalicylic Acid on the Occurrence of Rectal Aberrant Crypt Foci

Abstract

Background and Objectives: Aberrant crypt foci (ACF) are one of the earliest putative preneoplastic and, in some cases, neoplastic lesions in human colons. Many studies have confirmed the reduction of ACFs and colorectal adenomas after treatment with acetylsalicylic acid (ASA) commonly referred to as ASA; however, the minimum effective dose of ASA and the duration of use has not been fully elucidated. The objective of our study was to assess the significance of low dose ASA (75-mg internally once daily) to study the chemopreventive effect of ASA in ACF and adenomas development in patients taking this drug for a minimum period of 10 years. Materials and Methods: Colonoscopy, combined with rectal mucosa staining with 0.25% methylene blue, was performed on 131 patients. The number of rectal ACF in the colon was divided into three groups: ACF < 5; ACF 5−10; and ACF > 10. Patients were divided into two groups: the “With ASA” group (the study group subjects taking ASA 75-mg daily for 10 years); and “Without ASA” group (control group subjects not taking ASA chronically). The incidence of different types of rectal ACF and colorectal polyps in both groups of subjects was analysed and ascertained. Results: Normal ACF was found in 12.3% in the study group vs. 87.7% control group, hyperplastic 22.4% vs. 77.6%, dysplastic 25% vs. 75%, mixed 0% vs. 100%. Treatment with ASA affects the occurrence of colorectal adenomas. The amount of dysplastic ACFs was lower in the study group than in the control group. The increase in dysplastic ACFs decreases with age in both groups, with the increase greater in those not taking ASA. Conclusions: Patients who take persistent, chronic (>10 years) low doses of ASA have a lower total number of all types of rectal ACFs and adenomas compared to the control group.

Keywords: acetylsalicylic acid (ASA); colonoscopy; colorectal adenoma; colorectal cancer (CRC); rectal aberrant crypt foci (ACF).

Figure 1

Relationship of the incidence of rectal aberrant crypt foci (ACF) counts to with ASA or without ASA. The rate of ACF formation in patients without ASA is higher than in patients with ASA. There is a difference in the probability distributions of the occurrence of ACF count in patients with and without ASA and it is statistically significant according to the X2 criterion with a significance level of p < 0.05.

Figure 2

Incidence of dysplastic ACFs in the group with ASA and without ASA. The total number of dysplastic ACFs is higher in those without ASA. The increase in the number of dysplastic ACFs decreases with age in both groups (with ASA and without ASA), with the increase being greater in those without ASA.

Figure 3

Incidence of ACF normal in the group with ASA and without ASA. In those without ASA, the number of ACF normally increases rapidly in the age group 50–60 years, then decreases from age 60 years. In the group with ASA, there is a lower number of ACF normal.

Figure 4

Incidence of hyperplastic ACF in the group with ASA and without ASA. The number of hyperplastic ACFs in subjects without ASA is greater than those with ASA. In subjects without ASA, the number and increment of hyperplastic ACFs gradually decrease with age. In subjects with ASA, the number and increment of hyperplastic ACFs increases with age. The difference in the number of hyperplastic ACFs between with ASA and without ASA decreases with age, but even after age 70 there are more in those without ASA.

Figure 5

Incidence of ACF mixed in the group with ASA and without ASA. No ACF mixed was observed in subjects with ASA. In those without ASA, the increase in the number of ACF mixed decreases with age. After age 50, the number of this type of ACF is similar in all age groups in those without ASA.

Figure 6

Relationship of adenoma incidence in subjects with ASA and without ASA across age groups. With age, the intensity of adenoma growth decreases, although there is an apparent increase in the number of adenomas in the elderly. Without ASA affects the incidence of more adenomas compared to those with ASA. The curve of adenoma incidence in subjects without ASA can be described by the equation y = 4.6x with a coefficient of determination of 0.98.

Figure 7

Relationship of hyperplastic polyp incidence in people with ASA and without ASA by age groups. The number of hyperplastic polyps in people without ASA increases between the ages of 50–70 years and then decreases. The rate of growth of hyperplastic polyps in people without ASA decreases with age. In people taking ASA, the number of hyperplastic polyps increases in the age group of 50–60 years and then decreases to take an increasing trend again from the age of 70 years. The trend of decreasing rate of growth of these polyps is similar to that in people without ASA.

Figure 8

Relationship of serrated polyp incidence in subjects with ASA and without ASA by age groups. In subjects without ASA, the growth rate and total number of serrated polyps decreases with age. There is no increase in the number of serrated polyps in people with ASA between the ages of 50–70 years.