This report is the first to address the profile of ACPs in a cohort of symptomatic adult patients in Kuwait. Despite being a non-population-based study, significant data are presented. In our patients, the prevalence of ACPs was substantial among patients aged 50 years or more, and a considerable number of these patients had advanced adenoma.
The prevalence rates of ACPs vary considerably. An earlier study from Kuwait[13
] reported a prevalence of 4.6% for various types of colorectal polyps. In our study, the overall prevalence was comparatively higher. This might be attributed to higher mean age of our patients. Studies from different Asian countries on symptomatic patients showed a prevalence of 5.1% in India,[10
] 11.7% in Iran[14
] and 14.8% in 10 Asian countries according to reports from 17 endoscopy centers.[15
The variability in prevalence may be due to dissimilarity in indications for colonoscopy and in the proportion of patients who had high risk for ACPs, such as men, older patients, patients with positive fecal occult blood test and those with family history of CRC.[16
As reported in other studies,[14
] we did not find any significant association between the referring indication for colonoscopy and the detection of ACPs. However, in contrast to the notion that male gender predicts higher prevalence of adenoma,[21
] we found no significant gender-related association. This may be attributed to the relatively smaller number of females in this study. However, Bafandeh et al
. similarly found no association between gender and occurrence of ACPs in symptomatic Iranians referred for colonoscopy.[14
A significant number of ACPs were proximally located. Advanced proximal neoplasia may be missed if screening is done only by sigmoidoscopy.[11
] In our study, proximal ACPs were detected more frequently in patients with distal ACPs than in those without distal ACPs, which is supported by a meta-analysis of screening colonoscopy studies.[26
In addition, no age or gender difference with regard to site distribution of overall and advanced ACPs was observed in our patients; this has been noted in other studies as well.[10
] However, Imperiale et al
] and Lieberman et al
] have observed that age is an important risk factor for all proximal neoplasias regardless of distal findings. In addition, Anderson et al
] found male gender to be predictive of non-advanced proximal neoplasia.
Twenty-six percent of our patients with ACPs had villous component. In other studies, villous adenomas ranged from 10% to 38%.[10
] Villous polyps may become malignant in 29% to 70% of the cases.[30
The prevalence of advanced ACPs was slightly higher than that reported by Cheng et al
] (1.3%) but much lower than that reported by Sung et al
] (12.5%); and that reported by Lam et al
] who reported a peculiarly increasing prevalence of advanced colonic polyps in young patients undergoing colonoscopy in Hong Kong. Advanced ACPs have been reported to develop into cancer and to be predictive, after removal, of future advanced neoplasia.[32
] In our study, large ACPs were more likely to demonstrate advanced pathology. However, carcinoma in situ
and invasive cancers are sometimes found in small tubular adenomas (TA).[33
Increased polyp size, villous histology and severe dysplasia are all associated with an increased risk of malignancy in an adenoma. This risk is even greater for those who have multiple polyps.[34
] A total of 14 (26%) of our patients with ACPs had two or more polyps and thus carried high-risk adenomas. Additionally, and similar to other studies,[1
] it was found that the prevalence of overall and advanced adenomas increases substantially with advancing age, being more common over the age of 50 years.
Our study revealed a strong association between past history of colorectal adenomas and the adenoma detection on surveillance colonoscopy. Past history of adenoma increases the incidence of recurrent overall and advanced neoplasia.[28
] In addition, Kuwaiti nationals had almost 2-fold increased risk of ACPs when compared to non-Kuwaitis. The reasons for this higher risk are not clear. It is probable that higher exposure to western-type fatty diet and consequently higher incidence of obesity in Kuwaitis[38
] may be a contributory factor.
Although Kuwait is considered to be among the countries with low incidence of colorectal cancer, there has been an increasing trend in age-standardized rate (ASR) of colorectal cancer among Kuwaitis since 1988.[39
The last web-published data from the International Agency for Research on Cancer regarding cancer incidence in Kuwait showed ASR (per 100,000) during the period 1998-2002 for the colon and rectum cancers to be 8.4 and 5.2, respectively.[40
] Local unpublished data from the cancer registry in Kuwait has even shown further rise in ASR (per 100,000) of colon cancer to 9.2 among males and 9.5 among females.
It is relevant to mention that there is no screening program for CRC in Kuwait so far. Recommending a screening program requires population-based studies in asymptomatic average-risk individuals (aged ≥50 years), and its implementation will require strong collaboration between the primary health care sector and the specialized endoscopy centers.
Our study has certain limitations in that certain risk factors for ACPs like body mass index, smoking, alcohol and dietary pattern were not studied because of the restrictions associated with the retrospective nature of the study.
In conclusion, the prevalence of overall and advanced ACPs in our patients was significant. Most of the significant polyps were identified in patients aged 50 years or older, had a tubular type in histology and a considerable proportion of them had advanced pathology. Advancing age, being Kuwaiti nationals and past history of ACPs were significantly associated with the occurrence of ACPs.