Polyps and diverticula of the large intestine: a necropsy survey in Hong Kong

Prevalence of incidental colorectal cancer and polyps in autopsies of different populations: a systematic review with meta-regression analysis

The colorectal cancer (CRC) and polyps incidentally found in autopsies represent the lesions that have not actually caused problems throughout the lifetime and thus may not need to be removed during screening. This study aimed to investigate the prevalence of incidental CRC (iCRC) and polyps in autopsies of different populations. A systematic search was performed on 19 August 2022 to identify autopsy studies that provided data on prevalence of iCRC, adenomatous polyps, hyperplastic polyps, and/or all polyps combined. The prevalence was pooled with the random-effects model. Subgroup and multivariable meta-regression analyses were conducted to investigate the heterogeneity. Forty-three eligible studies including 59,656 autopsies were identified, with 94% conducted before 1990 when CRC screening was uncommon or not available. The pooled prevalence was 0.7% (95% confidence interval [CI], 0.3-1.2%) for iCRC, 18.4% (95% CI, 13.3-24.1%) for adenomatous polyps, 16.4% (95% CI, 8.7-25.9%) for hyperplastic polyps, 26.3% (95% CI, 15.4-38.8%) for all polyps combined, and 29.9% (95% CI, 14.8-47.6%) for iCRC plus polyps. The prevalence of iCRC was higher (1.2%) in white-predominant populations but lower (0.4%) after excluding low-quality studies. Multivariable analyses showed that the prevalence of polyps was higher in white-predominant populations and higher-quality studies, increased with age, and showed a downward trend from "before 1975" through "after 1985". In conclusion, the prevalence of iCRC in autopsies was not low, considering the average lifetime risk of CRC, while incidental polyps were common. Both varied greatly in different populations. These findings may have implications when weighing the benefits and harms of screening.

Pathophysiology of Diverticular Disease: From Diverticula Formation to Symptom Generation

Diverticular disease is a common clinical problem, particularly in industrialized countries. In most cases, colonic diverticula remain asymptomatic throughout life and sometimes are found incidentally during colonic imaging in colorectal cancer screening programs in otherwise healthy subjects. Nonetheless, roughly 25% of patients bearing colonic diverticula develop clinical manifestations. Abdominal symptoms associated with diverticula in the absence of inflammation or complications are termed symptomatic uncomplicated diverticular disease (SUDD). The pathophysiology of diverticular disease as well as the mechanisms involved in the shift from an asymptomatic condition to a symptomatic one is still poorly understood. It is accepted that both genetic factors and environment, as well as intestinal microenvironment alterations, have a role in diverticula development and in the different phenotypic expressions of diverticular disease. In the present review, we will summarize the up-to-date knowledge on the pathophysiology of diverticula and their different clinical setting, including diverticulosis and SUDD.

Sessile serrated lesions in patients with adenoma on index colonoscopy do not increase metachronous advanced adenoma risk

OBJECTIVES

Post-polypectomy surveillance intervals should be determined based on index colonoscopy findings. However, the risk of metachronous lesions, resulting from the coexistence of adenoma and sessile serrated lesions (SSLs), has rarely been addressed. We evaluated the impact of synchronous SSL on the risk of metachronous lesions within similar adenoma risk groups.

METHODS

We retrieved individuals with one or more adenomas on index colonoscopy in a single-center retrospective cohort and stratified them into four groups depending on the presence of SSL and low-risk/high-risk adenoma (LRA/HRA). Participants who underwent surveillance colonoscopies at least 12 months apart were included. We compared the risks of metachronous lesions including HRA, advanced adenoma (AA), or SSL within similar adenoma risk groups according to the presence of SSL.

RESULTS

Overall 4493 individuals were included in the analysis. The risk of metachronous HRA/AA was not significantly higher in the adenoma with SSL group compared with the adenoma without SSL group, irrespective of LRA (HRA, 6/86 vs. 231/3297, P = 1.00; AA, 0/86 vs. 52/3297, P = 0.64) or HRA (HRA, 11/64 vs. 240/1046, P = 0.36; AA, 3/64 vs. 51/1046, P = 1.00). However, the risk of metachronous SSL in individuals with synchronous SSL was higher than that in those without SSL for both LRA (15/86 vs. 161/3297, P < 0.001) and HRA groups (11/64 vs. 61/1046, P = 0.002).

CONCLUSION

The presence of synchronous SSL did not increase the risk of metachronous HRA/AA, compared with isolated adenoma, but increased the risk of metachronous SSL.

Colorectal polyp prevalence and aspirational detection targets determined using high definition colonoscopy and a high level detector in 2017

BACKGROUND

Colorectal adenoma prevalence can be determined by autopsy studies, or imaging studies such as colonoscopy. We describe the prevalence of colorectal adenomas determined by a single high detecting colonoscopist using high definition colonoscopes.

METHODS

We conducted a cross-sectional study of consecutive patients aged ≥18 years undergoing colonoscopy with a high level detector for the indications of screening, surveillance, and diagnostic reasons from December 29, 2016 to January 12, 2018.

RESULTS

During the study period, 1172 eligible patients underwent colonoscopy. Women comprised 55% (n = 646) and the majority (89%, n = 1038) were aged ≥50 years (mean age, 62.1 years). In persons aged ≥50 years undergoing screening, the prevalence of ≥1 conventional adenoma was 48.5% and ≥1 sessile serrated polyp was 15.3%. Diminutive polyps (1-5 mm in size) comprised three-quarters of all resected polyps (2236/2986). Among 246 patients (21%), 1050 hyperplastic appearing polyps were not resected from the recto-sigmoid. Adenoma prevalence was strongly associated with age and indication but serrated lesion prevalence was not.

CONCLUSIONS

The true prevalence of precancerous lesions in the colorectum determined by modern colonoscopy exceeds determination by autopsy studies. These data help define aspirational detection targets for colonoscopy. The economic burden associated with colonoscopic resection of tiny lesions is substantial.

Terminology, Molecular Features, Epidemiology, and Management of Serrated Colorectal Neoplasia

In addition to the adenoma to carcinoma sequence, colorectal carcinogenesis can occur via the serrated pathway. Studies have focused on clarification of categories and molecular features of serrated polyps, as well as endoscopic detection and risk assessment. Guidelines from the World Health Organization propose assigning serrated polyps to categories of hyperplastic polyps, traditional serrated adenomas, and sessile serrated lesions (SSLs). Traditional serrated adenomas and SSLs are precursors to colorectal cancer. The serrated pathway is characterized by mutations in RAS and RAF, disruptions to the Wnt signaling pathway, and widespread methylation of CpG islands. Epidemiology studies of serrated polyps have been hampered by inconsistencies in terminology and reporting, but the prevalence of serrated class polyps is 20%-40% in average-risk individuals; most serrated polyps detected are hyperplastic. SSLs, the most common premalignant serrated subtype, and are found in up to 15% of average-risk patients by high-detecting endoscopists. Variations in rate of endoscopic detection of serrated polyps indicate the need for careful examination, with adequate bowel preparation and sufficient withdrawal times. Risk factors for SSLs include white race, family history of colorectal cancer, smoking, and alcohol intake. Patients with serrated polyps, particularly SSLs and traditional serrated adenomas, have an increased risk of synchronous and metachronous advanced neoplasia. Surveillance guidelines vary among countries, but SSLs and proximal hyperplastic polyps require special attention in assignment of surveillance interval-especially in light of concerns regarding incomplete detection and resection.

Clinicopathological features of colorectal polyps in 2002 and 2012

BACKGROUND/AIMS

There are few comparative studies on the historical changes in the clinicopathologic characteristics of colorectal polyps in Korea. This retrospective study compared the clinicopathologic characteristics of colorectal polyps treated at our institution in 2002 and 2012.

METHODS

The medical records of 1,816 patients who underwent colonoscopy and were found to have colorectal polyps in 2002 (n = 597) or 2012 (n = 1,219) were reviewed retrospectively. Patient characteristics and polyp sizes, gross morphologies, locations, and pathologic results were analyzed and compared.

RESULTS

Mean age was older in the 2002 group than in the 2012 group (67.3 ± 11.1 years vs. 55.4 ± 10.8 years, p < 0.001). The 1,816 study subjects had a total of 3,723 colorectal polyps, with a mean of 2.05 polyps per patient. Mean polyp size was larger in the 2002 group than in the 2012 group (0.6 ± 0.4 cm vs. 0.4 ± 0.3 cm, p < 0.001). The most common histology was tubular adenoma and they were more common in the right colon in both study groups. Although the distribution of total adenoma was not significantly different between groups, the location of advanced adenoma differed significantly and was more common in the right colon in the 2012 group (30.4% vs. 63.2%, p = 0.01).

CONCLUSION

No significant change in total polyps and adenoma distribution was found between 2002 and 2012. However, advanced adenoma was more common in the right colon in 2012, which cautiously suggests a locational shift from the left to right colon. These findings indicate that right colon polyps require more attention.

The Natural History of Colonic Diverticulosis: Much Ado about Nothing?

BACKGROUND

Colonic diverticulosis is the most common incidental lesion found on routine colonoscopy. However, its true natural history is unclear. The aim of this review is to examine the epidemiology of colonic diverticulosis and the incidence of complications, namely acute diverticulitis and diverticular hemorrhage.

SUMMARY

Many studies have evaluated the epidemiology and risk factors of diverticulosis. Despite the common nature of this entity, little is known about the risk of complications in asymptomatic individuals. It has been suggested that the lifetime risk of acute diverticulitis is 10-25% and that of diverticular hemorrhage is 3-5%. These risk estimates were based on older literature without accurate studies on true prevalence. Three recent retrospective observational cohort studies including subjects identified at colonoscopy have addressed this issue, providing information on the long-term risk of complications of colonic diverticulosis. Cumulative data from these studies support an incidence of acute diverticulitis of 1.5-6.0 per 1,000 patient-years and 0.46 per 1,000 patient-years for diverticular hemorrhage.

KEY MESSAGES

Diverticulosis is a very common condition in individuals > 50 years of age. Based on population-based colonoscopy studies, the natural history of colonic diverticulosis appears favorable with a far lower incidence of complications than previously thought.

Implementation of real-time probe-based confocal laser endomicroscopy (pCLE) for differentiation of colorectal polyps during routine colonoscopy

BACKGROUND AND AIMS

 Probe-based confocal laser endomicroscopy (pCLE) is used to differentiate between neoplastic and non-neoplastic colorectal polyps during colonoscopy. We aimed to assess the accuracy of two endoscopists starting to use real-time pCLE for differentiation of colorectal polyps and to determine the negative predictive value (NPV) for neoplasia in polyps ≤ 5 mm.

METHODS

 Patients undergoing colonoscopy in a tertiary hospital were included in this prospective trial. After a training session, two colonoscopists assessed 50 polyps between August 2012 and April 2014. They sequentially used narrow-band imaging (NBI) and real-time pCLE to differentiate non-adenomatous, adenomatous, and carcinomatous polyps during colonoscopy. Histologic diagnosis by a gastrointestinal pathologist was the gold standard. Results were compared to post-hoc pCLE by a panel of gastroenterologists and pathologists.

RESULTS

 The accuracy of real-time pCLE was 76 %, compared to 73 % for NBI, and was not significantly different between the first 50 cases (74 %) and the last 50 cases (78 %, P  = 0.64). The accuracy in polyps > 5 mm was 87 % versus 59 % in polyps ≤ 5 mm ( P  = 0.04) and increased from 45 % (13/29) in poor quality images to 86 % (44/51) in fair quality images and 95 % (19/20) in good quality images ( P  < 0.01). The post-hoc pCLE accuracy was 62 %. The NPV for polyps ≤ 5 mm was 58 % for real-time pCLE and 54 % for post-hoc pCLE.

CONCLUSION

 Although a fair accuracy of real-time pCLE for differentiation of colorectal polyps can be achieved within 50 cases, low NPV and difficulty in obtaining high-quality pCLE images hamper implementation in routine clinical practice.

Distribution, size and shape of colorectal adenomas as determined by a colonoscopist with a high lesion detection rate: Influence of age, sex and colonoscopy indication

BACKGROUND

Increasing attention is focused on polyp-related features that may contribute to the operator-dependent nature of colonoscopy. Few data on polyps are available from high-yield colonoscopies, which may serve as a benchmark for quality control.

OBJECTIVES

Describe regional distribution, histology, size and shape of polyps, and the influence of patient age and gender, in colonoscopies performed by a colonoscopist with high lesion detection rate.

METHODS

Analysis of 698 consecutive patients with diagnostic, screening or surveillance colonoscopies.

RESULTS

In 704 colonoscopies, 1908 polyps were removed (360 were protruded and 1548 flat; 1313 were hyperplastic, 562 adenomas, 5 serrated adenomas and 8 mixed). There were 232 adenomas in female patients and 343 in male patients; 39% of the adenomas were protruded and 61% were flat. The peak adenoma detection rate (ADR) was 51% in patients beyond age 79 years. Men older than 49 years had a higher ADR than women. In men and women, respectively: 40% and 32% of adenomas were in the right colon, 31% and 22% were in the transverse colon, and 30% and 47% were in the left colon. Beyond age 59 years, the majority of adenomas were in the proximal colon.

CONCLUSIONS

An excess of adenomas in the proximal colon started at age 60 and this was more pronounced in men than in women. In all colonic regions, the majority of adenomas had a shape that was flat and smaller than 6 mm.

Prevalence and risk factors of asymptomatic colorectal diverticulosis in Taiwan

Background

To investigate the prevalence and risk factors of asymptomatic colorectal diverticulosis in Taiwanese general population.

Methods

From January 2009 to December 2011, consecutive asymptomatic subjects undergoing a health check-up were evaluated by colonoscopy. The colorectal diverticulosis was assessed, and a medical history and demographic data were obtained from each subject. Logistic regression analysis was conducted to search the risk factors of colorectal diverticulosis.

Results

Of the 1899 asymptomatic subjects, the prevalence of colorectal diverticulosis was 13.5%. On univariate logistic regression analysis, age over 60 years old, male, adenomatous polyp, current smoking and heavy alcohol consumption were significantly associated with diverticulosis. Multivariate logistic regression analysis revealed that age over 60 years old (relative risk [RR], 2.57; 95% confidence interval [CI], 1.64-6.47), adenomatous polyps (RR, 2.18; 95% CI, 1.18-4.61) and heavy alcohol consumption (RR, 1.82; 95% CI, 1.04-3.08) were independent predictors for colorectal diverticulosis.

Conclusions

The prevalence of asymptomatic colorectal diverticulosis was 13.5% in Taiwan. Age over 60 years old, adenomatous polyp and heavy alcohol consumption may affect the risk of development of the disease.

Routine colonic endoscopic evaluation following resolution of acute diverticulitis: Is it necessary?

Diverticular disease incidence is increasing up to 65% by age 85 in industrialized nations, low fiber diets, and in younger and obese patients. Twenty-five percent of patients with diverticulosis will develop acute diverticulitis. This imposes a significant burden on healthcare systems, resulting in greater than 300000 admissions per year with an estimated annual cost of $3 billion USD. Abdominal computed tomography (CT) is the diagnostic study of choice, with a sensitivity and specificity greater than 95%. Unfortunately, similar CT findings can be present in colonic neoplasia, especially when perforated or inflamed. This prompted professional societies such as the American Society of Colon Rectal Surgeons to recommend patients undergo routine colonoscopy after an episode of acute diverticulitis to rule out malignancy. Yet, the data supporting routine colonoscopy after acute diverticulitis is sparse and based small cohort studies utilizing outdated technology. While any patient with an indication for a colonoscopy should undergo appropriate endoscopic evaluation, in the era of widespread use of high-resolution computed tomography, routine colonic endoscopic evaluation following resolution of acute uncomplicated diverticulitis poses additional costs, comes with inherent risks, and may require further study. In this manuscript, we review the current data related to this recommendation.

Alcohol consumption is a risk factor for colonic diverticulosis

BACKGROUND AND AIM

The exact factors predisposing to colonic diverticulosis other than age are unknown.

METHODS

Cross-sectional study of asymptomatic subjects undergoing screening colonoscopy. A detailed dietary and social questionnaire was completed on all participants. A worldwide review of the literature was performed to further investigate any association between identified risk factors and diverticulosis.

RESULTS

Seven hundred forty-six consecutive individuals were enrolled (mean age, 61.1±8.3 y; female: male=0.98). Overall, the prevalence of diverticulosis was 32.8% (95% CI, 29.5-36.2). Diverticula were left-sided, right-sided, or both in 71.5%, 5.8%, and 22.7% of affected subjects, respectively. On univariate analysis, age, sex, adenomatous polyps, advanced neoplasia (adenoma≥1 cm, villous histology, or cancer), aspirin, and alcohol use were significantly associated with diverticulosis. Diet, body mass index, physical activity, and bowel habits were not associated with the disease. On multivariate analysis, increasing age (P<0.001), advanced neoplasia (P=0.021), and alcohol consumption (P<0.001) were significantly associated with diverticulosis. The adjusted odds ratio for diverticulosis in alcohol users was 1.91 (1.36 to 2.69), with increasing prevalence with higher alcohol consumption (P-value for trend=0.001). When the prevalence of diverticulosis reported from 18 countries was analyzed against alcohol use, there was a strong correlation with national per-capita alcohol consumption rates (Pearson correlation coefficient r=0.68; P=0.002).

CONCLUSIONS

Alcohol use is a significant risk factor for colonic diverticulosis and may offer a partial explanation for the existing East-West paradox in disease prevalence and phenotype. Further studies are needed to investigate this association and its putative pathophysiological mechanisms.

The changing trend of diverticular disease in a developing nation

AIM

Left-sided diverticular disease (LDD) is associated with reduced dietary intake, whereas right-sided diverticular disease (RDD) is more common amongst Oriental populations. We aimed to determine whether the prevalence, site and distribution of diverticular disease in our Oriental population has changed over the past two decades.

METHOD

A total of 1663 barium enema studies performed between January 2001 and August 2002 were reviewed retrospectively. The site of disease was correlated with age, gender and ethnicity of the patient.

RESULTS

Forty-five per cent of patients in the study population had diverticular disease. Older patients were more likely to have LDD, whereas the Chinese ethnic group was more likely to have RDD. Right-sided diverticular disease peaks at in the sixth decade, while for LDD this occurred in the seventh and eighth decades. Right-sided diverticular disease was more common in all age groups overall. When compared with two barium enema studies carried out in Singapore two decades earlier, there was a statistically significant increase in the incidence of RDD and LDD.

CONCLUSION

There is a positive association of RDD and LDD with Chinese race and increasing age. There is an increasing incidence of both LDD and RDD compared with two decades previously.

Endoscopic resection and histological evaluation of colorectal polyps: Is it a definitive treatment?

BACKGROUND AND AIMS

Primary aim of the present study was the evaluation of efficacy and safety of endoscopic polypectomy in a tertiary advanced endoscopic laboratory in Northwestern Greece. Additional aim was to estimate the effectiveness of endoscopic treatment of colorectal polyps and record the clinical course.

METHODS

One hundred and fifty consecutive patients (97 men) with colorectal polyps of size larger than 0.5 cm were included. The size, topography, shape and presence of pedicle were recorded for every polyp. Concerning the size, polyps were divided into: <1 cm, between 1-2 cm, >2 cm.

RESULTS

The rectum and sigmoid were the most common sites of detection (76.6%). Endoscopic resection was successful and the complication rate was very low (2.6%). The majority of the removed polyps were neoplastic (87.1%). Most neoplastic polyps were tubulovillous adenomas (50.8%). Low-grade dysplasia was detected in most of the polyps (82.9%), but highgrade dysplasia or invasive carcinoma was also detected in some patients. In total, 10 patients underwent surgical resection. Regular follow-up did not reveal significant residual polyps or recurrence of the lesions.

CONCLUSION

Endoscopic polypectomy is effective and safe and leads to complete resection of neoplastic polyps in the majority of cases.

Clinicopathological features of colon polyps from African-Americans

BACKGROUND AND AIMS

Among the ethnic groups, the age-standardized incidence rate of colorectal cancer (CRC) is highest among African-Americans. The majority of CRC arise from preexisting adenoma. It is shown that 30% of the US adult population has adenomas. The potential risk of malignant transformation in adenomas differs by specific pathologic and clinical characteristics that we aimed to study in AAs.

MATERIALS AND METHODS

All pathologic reports (150,000) in Howard University Hospital from 1959 to 2006 were reviewed manually. Those pathology reports compatible with the colorectal polyps were carefully reviewed and selected by a GI pathologist. All cases with cancer were then excluded from the list. Data were then entered into Microsoft Excel and checked for missing data and duplications. Differences in right-side and left-side polyps for sex, histology, and clinical symptoms were assessed by Chi-2 test.

RESULTS

A total number of 5,013 colorectal polyps were diagnosed in this period that include 47% male, with mean age (SD) of 63 (12). Half of the cases were diagnosed in 2001-2006. Tubular adenoma was the most frequent pathology (73%). The highest frequency of right-sided polyps was observed in the 1990s (56%). Left-sided polyps were younger (p < 0.0001), more hyperplasic (23 vs. 5%; p < 0.0001), and more frequent in female (56 vs. 52%; p = 0.02) compared to right-sided polyps. The frequency of right-sided adenoma significantly increases from 18% in the 1960s to 51% in the period of 2001-2006 (p < 0.0001). The most frequent symptom in both sides was GI bleeding (21%).

CONCLUSION

There was a ratio of 8:1 for neoplastic to hyperplastic polyps in our study, which is more than what has been reported in Caucasians (7:1). Our data shows a shift in polyps from the left side to the right side of the colon in recent years. This data is consistent with the lack of a reduction in the incidence of colon cancer in African-Americans. Screening is thus very important in AA to reduce the incidence of colon cancer.

Serrated colonic polyps in a teaching hospital in Saudi Arabia: prevalence and review of classification

BACKGROUND/AIM

To determine the prevalence of serrated colorectal polyps in the King AbdulAziz University Hospital population and to review the current classification of colorectal serrated polyps with emphasis on morphological features.

MATERIALS AND METHODS

This retrospective study used cases diagnosed with serrated colorectal polyps at the histopathology laboratory of King AbdulAziz University Hospital during last five years (2004-2008). The slides were reexamined microscopically and the lesions were renamed according to the terminology discussed in this article.

RESULTS

Diagnosed hyperplastic polyps represented 12.3% of all colorectal polyps submitted to our laboratory during the study period. However, the false positive rate was found to be 42.5%. Of the truly diagnosed serrated polyps, the most common subtype is the microvesicular serrated polyps. The majority of the serrated colorectal polyps was found in males, with a wide age range.

CONCLUSION

The prevalence of serrated colorectal polyps in our geographic area seems to be similar to that in western populations.

Hyperplastic and serrated polyps of the colorectum

The serrated polyp pathway is a histopathological sequence that begins in a hyperplastic polyp, or precursor serrated aberrant crypt focus, and has the potential to end in a colonic adenocarcinoma that is CIMP-high and, in most cases, also MSI. An activating mutation of the BRAF oncogene is a marker for this pathway. There is evidence that aberrant CpG-island methylation is the molecular engine that drives the progression through sequential steps of the pathway, from hyperplastic polyp to a form of atypical hyperplastic polyp (termed sessile serrated adenoma) to dysplastic serrated polyp and, ultimately to serrated carcinoma. A second serrated pathway, identified by mutations of KRAS in serrated adenoma, is delineated less completely. Its endpoint is a colorectal carcinoma that is CIMP-low and MSS, and both the advanced serrated adenoma and carcinoma stages of this pathway show molecular genetic and morphologic features that overlap with those of the conventional APC carcinogenic pathway. Clinical studies are needed to elucidate the natural history of serrated neoplasia, and provide evidence-based guidance for risk assessment and surveillance of individuals discovered to harbor its various serrated polyp precursors.

A hierarchical non-homogenous Poisson model for meta-analysis of adenoma counts

We use a hierarchical model for a meta-analysis that combines information from autopsy studies of adenoma prevalence and counts. The studies we included reported findings using a variety of adenoma prevalence groupings and age categories. We use a non-homogeneous Poisson model for multinomial bin probabilities. The Poisson model allows risk to depend on age and sex, and incorporates extra-Poisson variability. We evaluate model fit using the posterior predicted distribution of adenoma prevalence reported by the studies included in our analyses and validate our model using adenoma prevalence reported by more recent colonoscopy studies. For 1990, the estimated adenoma prevalence among Americans at age 60 is 40.3 per cent for men compared to 29.2 per cent for women.

[Cost-effectiveness of colorectal cancer screening]

Colorectal cancer (CRC) screening in France is based on a faecal occult blood test every two years in average risk subjects 50-74 years of age while other endoscopic or non-endoscopic screening methods are used in Europe and in the USA. Beside the reduced incidence of and mortality from CRC found in available studies, cost-effectiveness data need to be taken into account. Because of the delay between randomized controlled trials and clinical results, transitional probabilistic models of screening programs are useful for public health policy makers. The aim of the present review was to promote the implementation of cost-effectiveness studies, to provide a guide to analyze cost-effectiveness studies on CRC screening and, to propose a French cost effectiveness study comparing CRC screening strategies. Most of these trials were performed by US or UK authors and demonstrate that the incremental cost-effectiveness ratio varies between 5 000 and 15 000 US dollars/one year life gained, with wide variations: these results were highly dependent on the unit costs of the different devices as well as the predictive values of the screening tests. Although CRC screening programs have been implemented in several administrative districts of France since 2002, and the results of these randomized controlled trials using fecal occult blood have been updated, cost-effectiveness criteria need to be integrated; especially since the results of screening campaigns based on other tools such as flexible sigmoidoscopy should be available in 2007.

The rare epidemiologic coincidence of diverticular disease and advanced colonic neoplasia

BACKGROUND AND AIMS

In Western industrialised countries the prevalence of neoplastic colonic lesions and diverticular disease markedly increases with age. In contrast, the coincident occurrence of both diseases seems to fall below their individual epidemiologic estimates. Because directly comparing data are rare, this retrospective study evaluates the coincidence of neoplastic lesions and diverticular disease.

PATIENT AND METHODS

A total of 1,838 patients from 1986 to 2000 were admitted to the study. For 1,326 patients-56% male (n=741), 44% female (n=585), mean age 64 (+/-11.83 SD)-with a resection due to colonic cancer, the documented findings of colonoscopy, colonic contrast enema, and/or histopathology were analysed with regard to the prevalence of colonic diverticulosis. In 512 patients--51% male (n=263), 49% female (n=249), mean age 60 (+/-12.59 SD)--with a colonic resection due to diverticulitis, the synchronous or metachronous occurrence of neoplastic colonic lesions was recorded using the database of the Tumour Centre, Aachen. To compare the observed results with published epidemiology, statistical analysis included age-referred binomial tests and an age-stratified analysis (Cochran-Mantel-Haenszel test). Odds ratios (OR) were also calculated. P<0.05 was considered to indicate locally statistical significance.

RESULTS

In the cancer group, we found a statistically significant reduced rate of diverticula in nearly all age categories and the age-stratified analyses (corresponding OR 0.30-0.51). Consistently, the diverticulitis group revealed a statistically significant decreased rate of advanced colonic neoplastic lesion in nearly all age categories and all age-stratified analyses (corresponding OR 0.13-0.43).

CONCLUSION

Our results indicate that patients with colonic neoplastic lesions or diverticular disease probably form heterogeneous groups. Because current results from molecular biology emphasize the impact of the extracellular matrix on the genesis of diverticulosis and colonic cancer, the observed heterogeneity could be an expression of a distinct composition of the local milieu.

Generation of a unique strain of multiple intestinal neoplasia (Apc(+/Min-FCCC)) mice with significantly increased numbers of colorectal adenomas

The relevance of the Apc(+/Min) mouse model in the study of human colorectal cancer remains uncertain due to the predominance of small intestinal adenomas and few, if any, colorectal adenomas. A new strain of Apc(+/Min) mice (Apc(+/Min-FCCC)) with significantly greater numbers of colorectal adenomas has been generated and characterized. Male C57BL/6J-Apc(+/Min) mice (the Jackson Laboratory, Bar Harbor, ME) were crossed with wild-type (Apc(+/+)) C57BL/6J females from an independent colony at this institution (offspring=Apc(+/Min-FCCC)) and 233 animals were evaluated over 20 generations. In order to determine the contribution of genetics to the enhanced colorectal adenoma phenotype, breeding pairs (Apc(+/Min) male x wild type female C57BL/6J) were purchased from the Jackson Laboratory and offspring (Apc(+/Min-JAX)) were maintained in our facility under identical conditions (n=98). Animals were fed Purina Rodent chow (#5013) diet containing 5% fat. The entire intestinal tract was examined histopathologically in both strains. Both the Apc and Pla2g2a (candidate for Mom1) genes were sequenced and found to be identical for both the Apc(+/Min-FCCC) and Apc(+/Min-JAX) mouse strains. The multiplicity of colorectal adenomas in the Apc(+/Min-FCCC) mice was much higher than reported in the literature and significantly greater than the multiplicity of colorectal adenomas in Apc(+/Min-JAX) mice maintained in our facility (P=0.01). Apc(+/Min-FCCC) had a significantly greater incidence of rectal prolapse (P = 0.02) and small intestinal adenocarcinomes (P=0.001), and multiplicity of small intestinal adenocarcinomas (P=0.001) compared to Apc(+/Min-JAX) mice. Male Apc(+/Min-FCCC) mice had significantly greater numbers of colorectal adenomas compared to female Apc(+/Min-FCCC) mice (P=0.0002), as did male Apc(+/Min-JAX) mice vs. female Apc(+/Min-JAX) mice (P< 0.0001). These results allow us to conclude: (1) Apc(+/Min-FCCC) mice are unique in that they develop significantly greater numbers of colorectal adenomas and small intestinal cancers, and a significantly greater incidence of small intestinal cancers and rectal prolapse than Apc(+/Min-JAX) mice. (2) This study represents the first report of a significant gender difference in multiplicity of colorectal adenomas. (3) Differences between Apc(+/Min-FCCC) and Apc(+/Min-JAX) mice in currently undefined genetic modifiers may contribute to the enhanced colorectal phenotype. (4) The Apc(+/Min-FCCC) strain is highly suited for the investigation of colorectal neoplastic disease and chemoprevention studies.

Colonic diverticular disease in a multiracial Asian patient population has an ethnic predilection

BACKGROUND

Traditionally, diverticular disease of the colon has been attributed to ageing, low dietary fibre and a high intraluminal pressure. Recently, genetic and racial factors have also been implicated.

METHODS

Four-hundred and ten consecutive multiracial Asian patients undergoing colonoscopy for a variety of bowel symptoms in a private endoscopy unit were studied for differing frequencies (if any) in colonic diverticular disease and concomitant abnormalities.

RESULTS

Forty-one patients (10%) had diverticular disease. Diverticula were present in 22/147 Chinese (15%), 14/153 Indians (9%) and 5/110 Malays (4.5%). The mean age of patients with diverticular disease was 55 years as compared with 51.3 years in those without (P = 0.12) and there was no gender difference. Thirty-six patients (88%) had diverticula in the right colon only, four patients (10%) exclusively in the left hemicolon, and one patient (2%) had bilateral involvement. Using regression analysis, Chinese ethnicity [odds ratio (OR)=2.11; 95% confidence interval (CI), 1.09-4.09; P = 0.027), constipation (OR = 2.65; 95% CI, 1.23-5.42; P = 0.007) and colorectal adenomas (OR = 2.65; 95% CI, 1.08-6.46; P = 0.033) were independently associated with diverticular disease.

CONCLUSIONS

Colonic diverticular disease in a multiracial Asian patient population has an ethnic predilection and is predominantly right-sided.

Histopathological and clinical evaluation of serrated adenomas of the colon and rectum

We evaluated the diagnostic utility of the histological characteristics ascribed in the literature to serrated adenomas and developed a practical working model to allow their reliable identification. We also documented the frequency and location of serrated adenomas identified in an unselected series of individuals undergoing colonoscopic evaluation, as well as the clinical characteristics of those individuals. One hundred forty consecutive individuals (prospective polyp data set; 97 male, 43 female; age mean: 63.3 y; age range: 29-98 y) with 255 polyps were identified from 919 individuals undergoing colonoscopy. Further polyps previously removed from these individuals were added for the purpose of histological assessment (extended polyp data set, n = 380). All polyps were assessed by two independent examiners for eight selected architectural and cytological features of serrated adenomas. In the prospective polyp data set, 56 patients had 72 hyperplastic polyps, 7 had 9 serrated adenomas, 3 had 4 admixed polyps, and 98 had 170 conventional adenomas. There was no difference in the age, sex, or cancer association of the seven patients with serrated adenomas when compared with the case of other individuals with polyps. The prevalence of serrated adenomas was 9/919 (1%) in our population, with an average size of 5.8 mm. When assessing serrated adenomas histologically, the combination of nuclear dysplasia and serration of >/=20% of crypts provided the most accurate model for detection of these lesions (sensitivity 100%, specificity 97%). Other criteria provided supportive evidence but did not increase the diagnostic yield. The optimum model for the histological identification of the serrated adenoma includes the presence of a serrated architecture in >/=20% of crypts in association with surface epithelial dysplasia.

Epidemiology of diverticular disease

Diverticulosis, which is an acquired condition marked by mucosal herniation through defects in the colonic wall, has been termed both a "disease of the 20th century" and a "disease of Western civilization" due to its increasing prevalence in modern times and its striking geographical variability. Both of these epidemiological observations may provide interesting insights into the pathophysiology of diverticulosis. This chapter will review the known epidemiology of diverticulosis coli and its main complications: diverticulitis and diverticular haemorrhage. Where possible, attempts will be made to place these observational reports in the context of both the cause and clinical behaviour of this disorder.

Diverticular disease in the elderly

Diverticular disease is common among the elderly. Because of the advanced age and muted symptoms and signs of many of those affected, diagnosis can be difficult. Consequently, great demands are placed on the physician to diagnose and treat clinically evident diverticular disease. Endoscopic, radiologic, and surgical advances have increased the availability of more definitive therapies for patients with complicated diverticular disease and diverticular hemorrhage.

Dietary habits and right-sided colonic diverticulosis

PURPOSE

In Asian populations, there is a high prevalence of right-sided colonic diverticulosis, the cause of which is uncertain. It is suspected that dietary habits may interact with a congenital predilection to cause this condition. To evaluate the relationship between long-term dietary habits and the prevalence of right-sided diverticulosis in the general population, we performed a retrospective case-control study.

METHODS

We reviewed the records of 3,105 screening colonoscopies performed on healthy, asymptomatic adults. All cases of right-sided diverticulosis were selected, and a similar number of gender-matched and age-matched controls with negative colonoscopies were randomly sampled from the same cohort. All case and control subjects were interviewed by a single-blinded nurse to establish their dietary habits during the past decade, in addition to other demographic characteristics. Based on consumption frequency, they were assigned to one of three diet classes for each of three food categories of interest: meat, vegetable, and fruit products. Staple foods such as rice were not included. Odds ratios were then calculated using multivariate conditional logistic regression and tests for trend were performed.

RESULTS

A total of 86 cases of right-sided diverticulosis were included, whereas 106 controls were randomly selected. There was a marked association between meat consumption frequency and right-sided diverticulosis, with a trend P value of <0.01 and an odds ratio of 24.81 between the most and least frequent consumers of meat products.

CONCLUSIONS

The prevalence of right-sided diverticulosis is strongly positively associated with past meat consumption frequency. There is no association with vegetable or fruit consumption frequency, laxative use, supplemental fiber intake, smoking, or family history.

Advanced distal colonic lesions as predictors of advanced lesions in the proximal colon

The characteristics of adenomas found during sigmoidoscopy have been suggested to predict synchronous adenomas in the proximal colon. Our aim was to examine whether the presence and characteristics of distal colonic lesions are associated with the presence and characteristics of lesions in the proximal colon. We performed a university hospital based case-control study with 3,268 consecutive subjects who received colonoscopy between January 1992 and December 1995. Subjects who had a history of colonic polyps, inflammatory bowel disease, intestinal resection, or had a contraindication against biopsies were excluded. Number size, and histologic characteristics of polyps in the distal and proximal colon were recorded. Advanced lesions were defined as neoplastic lesions with 1 or more of the following features: 1) > or = 1 cm diameter, and/or 2) villous histology, and/or 3) severe dysplasia or carcinoma, and/or 4) > or = 3 lesions. We found that 439 patients had neoplastic lesions in the distal colon only (61.3% with advanced lesions), 198 patients had lesions in the proximal colon only (55.1% advanced), and 197 had lesions in both the distal colon (74.6% advanced) and the proximal colon (55.8% advanced). Distal lesions were significantly more often advanced in patients with synchronous proximal lesions compared with patients with lesions in the distal colon only (odds ratio: 1.9; 95% confidence interval [CI]: 1.3-2.8; p < 0.001). The odds ratios for finding any neoplastic lesion in the proximal colon and an advanced proximal lesion, respectively, were 3.7 (2.6-5.3) (p < 0.001) and 2.2 (1.3-3.7) (p < 0.01) when a nonadvanced lesion was found in the distal colon, and 6.8 (5.3-8.7) (p < 0.001) and 6.7 (4.9-9.0) (p < 0.001) when an advanced lesion was found in the distal colon. Logistic regression analysis revealed number of distal polyps and villous histology as independent predictors of advanced lesions in the proximal colon; size and severe dysplasia were not independent predictors. In conclusion, characteristics of neoplastic lesions in the distal colon predict the presence and characteristics of lesions in the proximal colon.

Distal hyperplastic polyps do not predict proximal adenomas: results from a multicentric study of colorectal adenomas

BACKGROUND

The association between distal hyperplastic polyps and proximal adenomas is still a matter of debate. We investigated this association while taking into account patient characteristics.

METHODS

After exclusion of patients with inflammatory bowel diseases, familial adenomatous polyposis, or any cancer, 3088 eligible consecutive subjects aged 18 to 69 years underwent total colonoscopy in four gastroenterology units. The odds ratios (OR) of having proximal adenomas according to patient characteristics (age, sex, medical center, year of endoscopy, reasons for referral, and distal findings) were estimated in univariate and multivariate analyses.

RESULTS

Patients with distal polyps of any type showed an adjusted OR of 2.5 (95% CI [1.9, 3.1] p < .001) of having proximal adenomas as compared with those without distal polyps. When distal adenomas and distal hyperplastic polyps were included in the multivariate model as independent factors, the presence of adenomas significantly increased the risk of proximal adenomas (OR = 2.8: 95% CI [2.2, 3.6] p < .001), whereas the presence of hyperplastic polyps did not (OR = 1.1: 95% CI [0.8, 1.5] p = .64). No association with number, size, or location of distal hyperplastic polyps was seen.

CONCLUSIONS

Our data show that the presence of hyperplastic polyps should not be the sole indication for total colonoscopy because they are not associated with proximal adenomas when adjusting for patient characteristics and presence of distal adenomas.

Clinical behavior of complicated right-sided and left-sided diverticulosis

PURPOSE

The aim of the study was to characterize the clinical entity of multiple right-sided (RS) diverticular disease, which is uniquely common in Asians.

METHODS

Patients hospitalized with proven diverticular disease from June 1989 to January 1996 were reviewed. Data were retrieved from a prospectively collected computerized database.

RESULTS

One hundred eighty consecutive patients were admitted to the Department of Colorectal Surgery, Singapore General Hospital, with multiple diverticular disease. Average age was 65.1 (standard error of the mean, 13.9) years. There were 96 men and 84 women. Women presented, on average, 8.4 years later than men (P < 0.005). Eighty-five patients (47 percent) had massive rectal bleeding, 65 (36 percent) had diverticulitis, 21 (12 percent) had obstructive symptoms, and 9 (15 percent) had enteric fistulas. The diverticula were RS in 76 patients(42 percent), left-sided (LS) in 62 patients (34 percent), and on both sides in 42 patients (24 percent). RS diverticulosis tended to present with massive rectal bleeding (42/76; 55 percent) more often than LS disease (14/62; 23 percent; P < 0.005). Surgery for bleeding was also required more often for RS (17/42; 41 percent) than for LS disease (1/14; 7 percent; P < 0.05); however, diverticulitis was more common on the left (RS, 25/76, 33 percent; LS, 32/62, 52 percent; P < 0.05). Seventy-eight patients (43 percent) required surgery for these complications of diverticular disease. At a mean follow-up of 15.2 (standard error of the mean, 2) months, mortality was 2 in 78 patients who underwent surgery (3 percent), and morbidity was 15 percent.

CONCLUSIONS

In comparison with LS, RS diverticular disease tended to present more often with massive bleeding than with diverticulitis and fistulation. This bleeding was often more severe and required surgical intervention.

Case report: calcified stones in right-sided colonic diverticula stimulating gallstones

Right-sided colonic diverticulosis, though unusual in the Western population, is common in the Orient. Calcified stones are rarely found within colonic diverticula. Standard textbooks of diagnostic radiology do not list calcified stones within caecal or ascending colonic diverticula as possible causes of calcification in the right hypochondrium or right iliac fossa. We present a patient with multiple laminated right-sided diverticular concretions mimicking gallstones. This possibility should be included in the differential diagnosis of gallstones or calcifications on the right side of the abdomen.

Incidence and recurrence rates of colorectal adenomas: a prospective study

BACKGROUND/AIMS

The frequency of colorectal adenomas, the precursor lesions for most cases of colorectal carcinoma, has been generally measured as prevalence rates of adenomas at autopsy or colonoscopy. The aim of this study was to estimate the incidence rate of adenomas and compare it with the adenoma recurrence rate.

METHODS

Data on colonoscopies performed in three New York City practices were collected prospectively. The cumulative rate of adenoma diagnosis on repeat colonoscopy was calculated for patients with no abnormalities on index colonoscopy ("incidence" rate) and for patients with adenomas on the index colonoscopy ("recurrence" rate).

RESULTS

The cumulative incidence rate of adenomas at 36 months was 16%, and the cumulative recurrence rate at 36 months was 42% (P < 0.004). The recurrence rate was higher in patients with multiple adenomas than in those with a single adenoma on index colonoscopy, although the increase was not statistically significant.

CONCLUSIONS

Although the recurrence rate has always been assumed to be elevated, this study is the first to compare the recurrence rate of adenomas with the incidence rate directly and to show that the recurrence rate is indeed elevated.

Diverticular disease. Epidemiology and pharmacological treatment

Diverticular disease is worldwide in distribution, but the incidence is highest in industrialised countries. It is associated with aging and low intake of dietary fibre. There is a broad range of clinical manifestations--from asymptomatic diverticula to life-threatening complications. Elderly patients often present with complicated diverticular disease, and may lack typical symptoms and signs. Treatment includes fibre supplementation, drugs or antibiotics for complications, and surgery for refractory disease. Proper diagnosis and treatment requires knowledge of the full range of presentations and careful selection and timing of medical versus surgical intervention.

Surgical management of cecal diverticulitis

Ninety surgical cases of cecal diverticulitis at the University of Hawaii hospitals were reviewed from 1980 to 1991. Seventy-eight percent of the study group were of Asian descent, with a mean age of 41.7 years. Right lower quadrant pain and tenderness were the only constant findings, occurring in 86 and 87 of the 90 patients, respectively. The most common preoperative diagnosis was acute appendicitis, occurring in 73% of patients. A right colectomy or cecectomy was performed in 49 patients, an appendectomy in 29, and a diverticulectomy in 10. Seventeen complications occurred, only 1 of which was in the appendectomy group. Follow-up of up to 10 years was successful in 27 of 29 appendectomy patients, only 4 of whom had recurrent pain. There were no instances of a missed cecal carcinoma. We concluded that in those patients in whom carcinoma can be ruled out and in whom there is no evidence of abscess formation, appendectomy combined with postoperative antibiotics is a safe and effective method for the treatment of cecal diverticulitis.

Adult polycystic kidney disease in Hong Kong Chinese: an autopsy study

To appraise the frequency, clinical features and prognosis of adult polycystic kidney disease (APKD) in Hong Kong, 41 Chinese patients who had an autopsy diagnosis of APKD were studied retrospectively. The APKD patients constituted 0.295% of 13,890 (or one in 339) autopsies performed during the study period (1964-1991). The frequency of APKD in autopsied populations in Western countries varies from one in 261 to one in 1,019 with an average of one in 503. Nineteen (46%) patients reached end-stage renal disease (ESRD) at the time of death. Ruptured berry aneurysm caused death in 3 patients while 3 others had spontaneous intracerebral hemorrhage. Left ventricular hypertrophy was found in 24 (59%) patients. Polycystic liver was present in 26 (63%) patients. This frequency was higher than the 4% to 60% (average 47%) reported in similar studies conducted in Western countries. The probability of patients being alive and without ESRD, estimated using a life table analysis, was 83%, 54%, 32% and 12% by the age of 40, 50, 60 and 70 respectively. No difference in frequency, clinical features and survival between male and female APKD patients could be demonstrated.

Predictors of presence, multiplicity, size and dysplasia of colorectal adenomas. A necropsy study in New Zealand

Three hundred and thirty six forensic necropsy specimens of large bowel were examined in order to identify subject related variables that independently predicted the following adenoma characteristics: presence, size (largest), multiplicity and high grade dysplasia. The variables were age, gender, body mass index, race (European origin versus Maori/Polynesian) and presence of hyperplastic (metaplastic) polyp(s). Subjects included 303 New Zealanders of European origin (M = 185, F = 118) yielding 149 adenomas and 251 hyperplastic polyps and 33 Maori/Polynesians (M = 25, F = 8) yielding five adenomas and one hyperplastic polyp. Independent predictors of adenoma presence as determined by regression analysis were age (p = 0.0001), presence of hyperplastic polyps (p = 0.0001) and male gender (p = 0.05). Models were poor at explaining variation in size, multiplicity, and dysplasia. Larger adenomas occurred more frequently in subjects with multiple adenomas (p = 0.03) and multiple adenomas were probably associated with hyperplastic polyps (p = 0.09) and male gender (p = 0.09) in Europeans. High grade dysplasia was more frequent in women (p = 0.05) and possibly in subjects with hyperplastic polyps (p = 0.2). Body mass index and ethnicity did not predict any adenoma characteristics, but hyperplastic polyp prevalence was influenced by European origin (p = 0.04) and to a lesser extent by body mass index (p = 0.08) as well as presence of adenoma (p = 0.0002) and age ( = 0.005). The association of hyperplastic polyp with presence, multiplicity but not size of adenoma and with a high risk group for colorectal cancer (New Zealanders of European origin) suggests that the hyperplastic polyp serves as a marker for a factor which influences neoplastic evolution at the stages of initiation/transformation but not promotion. Fifty nine per cent of individuals with adenoma(s) did not have hyperplastic polyp(s) emphasising that the last would serve only as a marker of populations and not individuals at high risk of bowel cancer. Low intracolonic butyrate may be the factor linking the expression of the two types of polyp.

Prevalence of colorectal polyps in Filipinos. An autopsy study

From May 1988 to May 1990, a prospective autopsy study was performed in patients who died at the Philippine General Hospital in Manila, Philippines. Patients younger than 10 years of age, patients with a history of large bowel resection, and patients whose deaths were related to trauma were excluded. There were 416 patients; 246 were males, and 170 were females. The mean age was 47 years (range, 11-95 years). Six of the 416 patients (1.4 percent) were found to have polyps. One patient had an inflammatory polyp, one was diagnosed with familial adenomatous polyposis, and one had an associated cecal carcinoma. Five "sporadic" adenomatous polyps were found in the remaining three patients (prevalence rate, 0.7 percent). All of the adenomatous polyps were located distal to the hepatic flexure and exhibited only mild atypia. The mean size was 6.4 mm (range, 2-20 mm). The incidence of colorectal adenomas in Filipinos is low compared with that in age-adjusted Western populations. This finding coincides with a low incidence of colorectal carcinoma. The documentation of a low risk for adenomatous polyps and colorectal cancer indicates that it would be difficult for massive screening programs to demonstrate a significant positive impact on the early detection of colorectal neoplasias in the Filipino general population.

Trends of diverticular disease of the large bowel in a newly developed country

Five hundred twenty four consecutive barium enemas done over an 18-month period were reviewed in Singapore to ascertain the prevalence and distribution of diverticular disease in the large bowel. In this study, the prevalence rate was 20 percent, which is comparable to European and American studies but higher than similar studies in Asian countries. However, the distribution of the disease showed a predominance of right-sided disease (70 percent). This is a pattern that is markedly different from that seen in Europe and North America, where the disease involves largely the left side of the large bowel. The high prevalence rate in this series is at variance with the widely held belief that diverticulosis occurs less frequently in oriental communities.

Primary colonoscopy

There is good evidence that colonoscopy, in expert hands, is the most accurate investigation for the diagnosis of colorectal disease, and it also allows histological confirmation and therapeutic procedures to be carried out. Furthermore, by screening high-risk groups together with regular follow-up of patients with known colorectal neoplasia and surveillance of long-standing ulcerative colitis patients, it may be possible to reduce the incidence of colorectal cancer. However, at the present time, the lack of widespread availability and the variability in the quality of examinations precludes the employment of colonoscopy as the first-line investigation in colorectal disease. Flexible sigmoidoscopy combined with good quality double contrast barium enema is a reasonable alternative in the majority of cases, reserving colonoscopy for investigation of the elderly and high-risk patients, together with surveillance of patients with premalignant conditions. Technologically, colonoscopy has probably reached its peak and it is now necessary to make provision for more widely available colonoscopy services, provided by adequately trained endoscopists who can guarantee total colonoscopy in more than 90% of cases safely and rapidly. This requires structured training programmes for gastrointestinal physicians and surgeons and ultimately changes in patterns of working practice if adequate numbers of colonoscopy sessions capable of dealing with a steadily increasing workload are to be achieved.

Schistosomal colonic disease

This study evaluates 216 patients with schistosomal colonic disease, diagnosed by endoscopic biopsies at the Armed Forces Hospital, Riyadh. The colonoscopic appearance was suggestive of schistosomiasis in 98 of these patients (45.37%), Schistosoma mansoni ova in stool was detected in only 24 of these 216 patients (11.11%). The most common histopathological finding in colonic biopsies of these patients was Schistosoma mansoni ova in the colonic mucosa with no or mild inflammatory cells infiltrates. These findings correlate with the endoscopic appearances in most patients. The most common symptoms were abdominal pain or distention in 84 patients (38.88%). Sixty five patients (30.09%) had hepatosplenic schistosomiasis. Eight patients had schistosomal polyps and two patients had colonic malignancy in which no association between their malignancy and Schistosoma mansoni infection was established. After antischistosomal treatment follow up, sigmoidoscopy was normal in 28 patients who previously had abnormal endoscopic appearances. Colonoscopic examination is valuable in colonic schistosomiasis as it can show characteristic colonic lesions and colonic biopsies are diagnostic and correlates with histological findings.

Colorectal carcinoma in Hong Kong Chinese. A pathological survey of 1,117 cases, 1972-1981

Hong Kong Chinese, when compared with the world population, have an intermediate incidence rate for colorectal carcinoma. The purpose of this retrospective analysis of a large number of colorectal carcinomas (1,117 cases) was to explore possible differences between this series and others, and to re-examine the divergent features reported in a smaller series. The present study revealed a distribution by age, sex, site and Dukes' stage, as well as histopathological features, which were analogous to those reported from other countries. Thus, while the incidence is lower in this group, the other manifestations of the disease are very similar to those seen elsewhere. The implication is that, apart from varying incidence, there is a global similarity among colorectal tumours.

Polyps of the large intestine in Aarhus, Denmark. An autopsy study

In 336 consecutive autopsies a total of 305 tumors were recorded in the large intestine. Of these, 184 were adenomas occurring in 26% of the 196 men and 17% of the 140 women, resulting in an overall prevalence of 22%, or 15% when standardized to the world standard population (WSP). The prevalence of adenomas increased with age, and a shift from distal to proximal location occurred in the older age groups, mostly accounted for by the greater tendency to multiplicity in old age. Regardless of age 57% of the cases of adenomas could have been identified by flexible sigmoidoscopy. The prevalence of hyperplastic polyps was 13%, and an association between these and adenomas was found. Five adenocarcinomas occurred in the study. With some exceptions, which are discussed in detail, the results are in accordance with studies from other countries with a high incidence of colorectal cancer and similar socioeconomic composition. The study supports the theory of the adenoma-carcinoma sequence.

Do all colorectal carcinomas arise in preexisting adenomas?

In this article, the underlying nature of the adenoma is defined and evidence in support of the adenoma-carcinoma sequence is presented. Emphasis is placed on recent findings from the field of molecular biology which fortify the concept of the adenoma as a step in the evolution of large bowel cancer. Despite the considerable body of indirect evidence in support of the adenoma-carcinoma sequence, the de novo theory still has some support. Although differences between the de novo and adenoma carcinoma concept are largely semantic, the fact that infiltrating carcinoma can arise within small, flat foci of severely dysplastic epithelium (indistinguishable from carcinoma in situ) may be of considerable clinical importance. Other routes of morphogenesis exist also, but these make a relatively small contribution to the overall incidence of colorectal cancer. Even if it is accepted that the majority of colorectal cancers develop in a preexisting adenoma, the systematic removal of adenomas would pose a number of practical difficulties. First, adenomas are extremely common, particularly in populations at high risk of colorectal cancer. A second factor is the recently recognized existence of flat or depressed adenomas which may be small and difficult to visualize endoscopically. A simple screening program based on our knowledge of the evolution of colorectal cancer is outlined.

Polyps of the colon in Barcelona, Spain. An autopsy study

This study is based on a prospective survey of 212 autopsies that was conducted to determine the prevalence of colon adenomas in Barcelona, Spain. Adenomatous polyps were found in 21.7% of the patients (29.3% of the men and 12.5% of the women); multiple adenomas were found in 40% of the patients. Almost all adenomas were less than 5 mm in diameter, although 6.7% of the ones seen predominantly in the rectosigmoid colon were larger than 1 cm. The prevalence and number of adenomas increases with age. The prevalence of hyperplastic polyps was very low (1.6%). The data shows a relationship between the prevalence of colon adenomas in Spain and the incidence of colon cancer. The prevalence of colon adenomas in Spain is one of the lowest compared with that in other European countries and North America.

Incidental carcinoma of the colorectum at autopsy and its effects on the incidence and future trends of colorectal cancers in Singapore

Ten incidental invasive carcinomas (two early carcinomas involving the submucosa, and eight advanced carcinomas involving the muscularis propria or beyond) of the large intestine were discovered in a series of 1014 consecutive autopsies. All occurred in Chinese aged 60 years and older, constituting a prevalence rate of about 3% in this age group. If unsuspected colorectal carcinomas in Chinese Singapore residents aged 60 years and older exist in those who died in 1984 to the same extent as that noted in this autopsy study, it was estimated that 146 additional cases would have been added to the Cancer Registry in that year. This would constitute 47.9% of the total number of colorectal cancers diagnosed in this age group in 1984. This potential contribution has to be taken into consideration in epidemiologic studies on the incidence and future trends of colorectal cancers in Singapore. It was observed further that incidental carcinomas were found predominantly in the ascending colon. With more frequent use of colonoscopy, the incidence of right-sided cancers of the large bowel may be expected to increase. The current underdiagnosis of ascending colon carcinomas has to be taken into consideration when any future increase in right-sided cancers of the large bowel is observed.

Age-dependent shift-to-the-right in the localization of colorectal adenomas

The age-dependent prevalence and topographical distribution of colorectal adenomas was investigated in 1006 unselected autopsies (554 males and 452 females) in Mainz, FRG. In 200 out of 1006 autopsies (19.8%) a total of 498 adenomas of the large intestine were detected. The percentage of patients with adenomas increased continuously with age. Only 6% of all adenomas were localized in the caecum and 8% in the rectum, whereas all the other adenomas were distributed rather evenly throughout the ascending colon (23%), the transverse colon (25%), the descending colon (15%) and the sigmoid colon (23%). Analyzing the topographical distribution of adenomas for definite age groups (40-59, 60-69, 70-79 and 80-99 years of age), it became evident that the topographical distribution is not constant, but shows an age-dependent shift-to-the-right, i.e. with advancing age an increase in the relative frequency of adenomas in the proximal colonic segments (from caecum to transverse colon) and a decrease in the distal segments (from descending colon to rectum). This shift to the right, which evolves continuously from the youngest to the oldest age group, results from a disproportionate increase in the absolute number of adenomas in the proximal colonic segments when compared with the distal segments. The age-dependent shift-to-the-right of colorectal adenomas provides an important confirmation of the adenoma-carcinoma sequence, but cannot be explained by current concepts concerning the aetiology of colorectal adenomas and carcinomas.