The epidemiology of colorectal polyps: prevalence in New Orleans and international comparisons

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.

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.

Intake consumption of ginsenoside Rg3, profiling of selected cytokines, and development of rectal polyps

Background: Rectal polyps is a major risk factor for rectal cancer. There is a need to explore a panel of preventive measures, as well as reliable biomarkers for screening of rectal polyps.

Patients and methods: We conducted a case control study which aimed to explore the effects of regular consumption of ginsenoside Rg3, profiling of selected cytokines, and development of rectal polyps in a Chinese population.

Results: Significantly higher levels of IL-4, MIP-1β, FasL, TGF-β1, and RANTES were detected in rectal polyp cases. Further, we found significant dose-response relationships between quartile-categorized levels of IL-4, MIP-1β, FasL, and TGF-β1, and risk of rectal polyps. The strongest associations for IL-4, MIP-1β, FasL, and TGF-β1 were observed for the highest quartile vs the lowest quartile with an OR of 1.78, 2.70, 1.49, and 2.36, respectively. Compared with non-Rg3 consumers, regular Rg3 consumers had a significantly lower risk of rectal polyps (OR =0.71; 95% CI: 0.55–0.92; P=0.009). We also found that Rg3 consumers had significantly lower levels of IL-4, MIP-1β, FasL, and TGF-β1 than non-Rg3 consumers, in both rectal polyp cases and healthy controls.

Conclusion: These results indicate that regular consumption of Rg3 might prevent the occurrence of rectal polyps through decreasing the serum level of selected cytokines, including IL-4, MIP-1β, FasL, and TGF-β1. Further clinical trials and prospective cohort studies with larger sample sizes are warranted to validate the anti-inflammatory activity and the anti-tumorigenic role of Rg3.

The role of inherited genetic variants in colorectal polyposis syndromes

Colorectal carcinoma (CRC) is the third most common cancer in men and the second most common cancer in women across the world. Most CRCs occur sporadically, but in 15-35% of cases, hereditary factors are important. Some patients with an inherited predisposition to CRC will be diagnosed with a "genetic polyposis syndrome" such as familial adenomatous polyposis (FAP), MUTYH-associated polyposis (MAP), polymerase proofreading associated polyposis (PPAP), NTHL1-associated polyposis, MSH3-associated polyposis or a hamartomatous polyposis syndrome. Individuals with ≥10 colorectal polyps have traditionally been referred for genetic diagnostic testing to identify APC and MUTYH mutations which cause FAP and MAP respectively. Mutations are found in most patients with >100 adenomas but in only a minority of those with 10-100 adenomas. The reasons that diagnostic laboratories are not identifying pathogenic variants include mutations occurring outside of the open reading frames of genes, individuals exhibiting generalized mosaicism and the involvement of additional genes. It is important to identify patients with an inherited polyposis syndrome, and to define the mutations causing their polyposis, so that the individuals and their relatives can be managed appropriately.

Frequency of coexistent carcinoma in sessile serrated adenoma/polyps and traditional serrated adenomas removed by endoscopic resection

BACKGROUND AND STUDY AIMS

Sessile serrated adenoma/polyps (SSA/Ps) have a different potential than traditional adenomatous polyps for developing into malignant colorectal cancer. However, little is known about the coexistent cancer rate. Here, we evaluate the frequency of carcinoma in serrated polyps removed by endoscopic resection (ER).

PATIENTS AND METHODS

This was a retrospective single-center cohort study of consecutive patients with colorectal polyps who underwent ER from March 2003 to October 2014. We determined the frequency of serrated polyps among all resected colorectal polyps and analyzed the clinicopathological findings as well as the frequency and characteristics of coexistent carcinoma in the serrated polyps resected by ER based on pathology reports.

RESULTS

A total of 21,048 polyps from 15,326 patients were identified, including 15,984 traditional adenomatous polyps (75.9 %), 621 SSA/Ps (3.0 %), 136 traditional serrated adenomas (TSAs) (0.6 %), 1,121 hyperplastic polyps (5.3 %), and 3,186 polyps of other types (15.1 %). The clinical and endoscopic findings of SSA/Ps revealed a male predominance (68.6 %), with 61.7 % of the polyps located in the proximal colon. Males accounted for 77.2 % of all patients with TSAs, and 77.2 % of these polyps were located in the distal colon. The mean sizes of the SSA/Ps and TSAs were 8.8 and 10.7 mm, respectively. Among the SSA/Ps, 8 (1.3 %) cases had coexistent carcinoma, and 1 (0.7 %) patient with TSA showed coexistent carcinoma. In the patients with SSA/Ps, female sex and a tumor size ≥ 10 mm were predictive factors for coexistent carcinoma.

CONCLUSIONS

The frequency of SSA/Ps with carcinoma was lower than that for traditional adenoma. Female sex and tumor size ≥ 10 mm were significant predictive factors for coexistent carcinoma.

Sessile serrated polyp prevalence determined by a colonoscopist with a high lesion detection rate and an experienced pathologist

BACKGROUND

The prevalence of sessile serrated adenomas and/or polyps (SSA/Ps) is uncertain.

OBJECTIVE

To determine the prevalence of SSA/Ps and SSA/Ps with cytologic dysplasia (SSA/P-CD) by using a colonoscopist with a high lesion detection rate and an expert in serrated lesion pathology.

DESIGN

Retrospective screening colonoscopy study.

SETTING

Academic endoscopy unit.

PATIENTS

A total of 1910 average risk, asymptomatic patients aged ≥50 years underwent screening colonoscopy between August 2005 and April 2012 by a single colonoscopist with a high lesion detection rate.

INTERVENTIONS

Slides of all lesions in the serrated class proximal to the sigmoid colon and all rectal and sigmoid colon serrated lesions >5 mm in size were reviewed by an experienced GI pathologist.

MAIN OUTCOME MEASUREMENTS

Prevalence of SSA/Ps, defined as the proportion of patients with ≥1 SSA/P.

RESULTS

There were 1910 patients, of whom 389 had 656 lesions in the serrated class. Review by the experienced GI pathologist determined a prevalence of SSA/Ps without cytologic dysplasia of 7.4% and SSA/Ps-CD of 0.6% (total SSA/P prevalence 8.1%). SSA/Ps and SSA/Ps-CD comprised 5.6% and 0.3%, respectively, of all resected polyps. The mean size of SSA/Ps was 7.13 mm (standard deviation [SD] 4.66), and 51 of 77 (66.2%) polyps ≥10 mm in the serrated class were SSA/Ps.

LIMITATIONS

Retrospective design.

CONCLUSION

A colonoscopist with a high lesion detection rate and an experienced pathologist identified a high prevalence (8.1%) of SSA/Ps in a screening population. SSA/Ps are more common than previously believed.

Types and patterns of colonic polyps encountered at a tertiary care center in a developing country in South Asia

PURPOSE

To identify the prevalence, types, and patterns of colonic polyps in a cohort of patients presenting to a tertiary care referral center in Sri Lanka.

METHODS

Endoscopy and pathology reports of a single unit from 2006 to 2013 were analyzed retrospectively. Spearman's correlation coefficient and chi-square test were used to identify correlations.

RESULTS

There were a total of 158 patients (M : F, 10 : 57) who had polyps encountered on colonoscopy (n = 1408) and flexible sigmoidoscopy (n = 2402) with an incidence of 4.1%. Mean age was 56.5 years (SD 16.4) and the incidence of polyps increased with age. The majority (81.6%) had one polyp. A total of 188 polyps were assessed and most were seen in the rectum (33.5%) followed by sigmoid colon (22.9%). The commonest histological type was tubulovillous adenoma (33.5%) followed by tubular adenoma (24.5%). Most polyps were benign (91.5%). There was no statistically significant correlation with age or gender with malignancy, site, or histology.

DISCUSSION AND CONCLUSION

The incidence of colorectal polyps was lower than the values reported in the west. More polyps were identified in males. There was no statistically significant association between age, gender, or multiplicity and malignant change in the polyps.

Serrated lesions of the colorectum: review and recommendations from an expert panel

Serrated lesions of the colorectum are the precursors of perhaps one-third of colorectal cancers (CRCs). Cancers arising in serrated lesions are usually in the proximal colon, and account for a disproportionate fraction of cancer identified after colonoscopy. We sought to provide guidance for the clinical management of serrated colorectal lesions based on current evidence and expert opinion regarding definitions, classification, and significance of serrated lesions. A consensus conference was held over 2 days reviewing the topic of serrated lesions from the perspectives of histology, molecular biology, epidemiology, clinical aspects, and serrated polyposis. Serrated lesions should be classified pathologically according to the World Health Organization criteria as hyperplastic polyp, sessile serrated adenoma/polyp (SSA/P) with or without cytological dysplasia, or traditional serrated adenoma (TSA). SSA/P and TSA are premalignant lesions, but SSA/P is the principal serrated precursor of CRCs. Serrated lesions have a distinct endoscopic appearance, and several lines of evidence suggest that on average they are more difficult to detect than conventional adenomatous polyps. Effective colonoscopy requires an endoscopist trained in the endoscopic appearance of serrated lesions. We recommend that all serrated lesions proximal to the sigmoid colon and all serrated lesions in the rectosigmoid > 5 mm in size, be completely removed. Recommendations are made for post-polypectomy surveillance of serrated lesions and for surveillance of serrated polyposis patients and their relatives.

Adverse events in older patients undergoing colonoscopy: a systematic review and meta-analysis

BACKGROUND

Studies suggest that advancing age is an independent risk factor for experiencing adverse events during colonoscopy. Yet many of these studies are limited by small sample sizes and/or marked variation in reported outcomes.

OBJECTIVE

To determine the incidence rates for specific adverse events in elderly patients undergoing colonoscopy and calculate incidence rate ratios for selected comparison groups.

SETTING AND PATIENTS

Elderly patients undergoing colonoscopy.

DESIGN

Systematic review and meta-analysis.

MAIN OUTCOME MEASUREMENTS

Perforation, bleeding, cardiovascular (CV)/pulmonary complications, and mortality.

RESULTS

Our literature search yielded 3328 articles, of which 20 studies met our inclusion criteria. Pooled incidence rates for adverse events (per 1000 colonoscopies) in patients 65 years of age and older were 26.0 (95% CI, 25.0-27.0) for cumulative GI adverse events, 1.0 (95% CI, 0.9-1.5) for perforation, 6.3 (95% CI, 5.7-7.0) for GI bleeding, 19.1 (95% CI, 18.0-20.3) for CV/pulmonary complications, and 1.0 (95% CI, 0.7-2.2) for mortality. Among octogenarians, adverse events (per 1000 colonoscopies) were as follows: cumulative GI adverse event rate of 34.9 (95% CI, 31.9-38.0), perforation rate of 1.5 (95% CI, 1.1-1.9), GI bleeding rate of 2.4 (95% CI, 1.1-4.6), CV/pulmonary complication rate of 28.9 (95% CI, 26.2-31.8), and mortality rate of 0.5 (95% CI, 0.06-1.9). Patients 80 years of age and older experienced higher rates of cumulative GI adverse events (incidence rate ratio 1.7; 95% CI, 1.5-1.9) and had a greater risk of perforation (incidence rate ratio 1.6, 95% CI, 1.2-2.1) compared with younger patients (younger than 80 years of age). There was an increased trend toward higher rates of GI bleeding and CV/pulmonary complications in octogenarians but neither was statistically significant.

LIMITATIONS

Heterogeneity of studies included and not all complications related to colonoscopy were captured.

CONCLUSIONS

Elderly patients, especially octogenarians, appear to have a higher risk of complications during and after colonoscopy. These data should inform clinical decision making, the consent process, public health policy, and comparative effectiveness analyses.

Colorectal cancer screening and surveillance in the elderly patient

Colorectal cancer (CRC) is the third leading cause of cancer-related deaths in the United States. Older age is associated with a rise in colorectal cancer and adenomas, necessitating the need for CRC screening in older patients. However, decisions about CRC screening and surveillance in older adults are often difficult and challenging. The decision requires an individualized assessment that incorporates factors unique to performing colonoscopy in older adults in order to weigh the risks and benefits for each patient according to their overall health and preferences. This review addresses the factors unique to colorectal cancer and performing colonoscopy in older adults that are relevant in weighing the risks and benefits of screening and surveillance in this population.

Prevention, screening and treatment of colorectal cancer: a global and regional generalized cost effectiveness analysis

BACKGROUND

Regional generalized cost-effectiveness estimates of prevention, screening and treatment interventions for colorectal cancer are presented.

METHODS

Standardised WHO-CHOICE methodology was used. A colorectal cancer model was employed to provide estimates of screening and treatment effectiveness. Intervention effectiveness was determined via a population state-transition model (PopMod) that simulates the evolution of a sub-regional population accounting for births, deaths and disease epidemiology. Economic costs of procedures and treatment were estimated, including programme overhead and training costs.

RESULTS

In regions characterised by high income, low mortality and high existing treatment coverage, the addition of screening to the current high treatment levels is very cost-effective, although no particular intervention stands out in cost-effectiveness terms relative to the others.In regions characterised by low income, low mortality with existing treatment coverage around 50%, expanding treatment with or without screening is cost-effective or very cost-effective. Abandoning treatment in favour of screening (no treatment scenario) would not be cost effective.In regions characterised by low income, high mortality and low treatment levels, the most cost-effective intervention is expanding treatment.

CONCLUSIONS

From a cost-effectiveness standpoint, screening programmes should be expanded in developed regions and treatment programmes should be established for colorectal cancer in regions with low treatment coverage.

Clinical predictors of colorectal polyps and carcinoma in a low prevalence region: Results of a colonoscopy based study

AIM: To estimate the prevalence of colorectal cancer (CRC) in patients with long lasting colonic symptoms undergoing total colonoscopy; and to establish clinical features predicting its occurrence.

METHODS: This prospective study was carried out in Imam Hospital, Tabriz University of medical sciences, Iran. Continuous patients with long lasting lower gastrointestinal tract symptoms who had the criteria of a colonoscopy were included. The endoscopist visualized the caecum documented by a photo and/or a specimen from terminal ileum.

RESULTS: Four hundred and eighty consecutive symptomatic patients [mean age (SD): 42.73 (16.21)] were included. The prevalence of colorectal neoplasia was 15.3% (34 subjects) and 37.7% (181 subjects) had a completely normal colon. Adenomatous polyps were detected in 56 (11.7%) patients, in 12.3% of men and 10.9% of women. The mean age of the patients with a polyp was significantly higher than the others (49.53 ± 14.16 vs 41.85 ± 16.26, P = 0.001). Most of the adenomatous polyps were left sided and tubular; only 22.5% of polyps were more than 10 mm. Cancer was detected in 16 (3.6%) of our study population, which was mostly right sided (57.2%). The mean age of patients with cancer was significantly higher than the others (60.25 ± 8.26 vs 42.13 ± 16.08, P < 0.005) and higher than patients with polyps [60.25 (8.26) vs 49.53 (1.91) (P < 0.0005)]. None of the symptoms (diarrhea, abdominal pain, rectal bleeding, constipation, altering diarrhea and constipation, history of cancer, known irritable bowel disease, history of polyp and fissure or family history of cancer) were predictors for cancer or polyps, but the age of the patient and unexplained anemia independently predicted cancer.

CONCLUSION: Less advanced patterns and smaller sizes of adenomas in Iran is compatible with other data from Asia and the Middle East, but in contrast to western countries. Prevalence of colonic neoplasia in our community seems to be lower than that in western population. Colonic symptoms are not predictors for polyps or cancer but unexplained anemia and elder age can predict CRC.

Are we finally winning the war on cancer?

President Nixon declared what came to be known as the “war on cancer” in 1971 in his State of the Union address. At first the war on cancer went poorly: despite a substantial increase in resources, age-adjusted cancer mortality increased by 8 percent between 1971 and 1990, twice the increase from 1950 through 1971. However, between 1990 and 2004, age-adjusted cancer mortality fell by 13 percent. This drop translates into an increase in life expectancy at birth of half a year—roughly a quarter of the two-year increase in life expectancy over this time period and a third of the increase in life expectancy at age 45. The decline brings cancer mortality to its lowest level in 60 years. In the war on cancer, optimism has replaced pessimism. In this paper, I evaluate the reasons for the reduction in cancer mortality. I highlight three factors as leading to improved survival. Most important is cancer screening: mammography for breast cancer and colonoscopy for colorectal cancer. These technologies have had the largest impact on survival, at relatively moderate cost. Second in importance are personal behaviors, especially the reduction in smoking. Tobacco-related mortality reduction is among the major factors associated with better health, likely at a cost worth paying. Third in importance, and more controversial, are treatment changes. Improvements in surgery, radiation, and chemotherapy have contributed to improved survival for a number of cancers, but at high cost. The major challenge for cancer care in the future is likely to be the balancing act between what we are able to do and what it makes sense to pay for.

Sensitivity of immunochemical fecal occult blood test to small colorectal adenomas

BACKGROUND

Although the immunochemical fecal occult blood test (FOBT) is reportedly more sensitive to large adenomas or colorectal cancer (CRC) than the guaiac-based FOBT, the sensitivity of the immunochemical FOBT to small adenomas has scarcely been reported. Previous reports have indicated that the guaiac-based FOBT can detect small adenomas only by serendipity.

OBJECTIVES

To investigate the sensitivity of immunochemical FOBT to small adenomas using a large-scale cohort.

METHODS

We analyzed 21,805 consecutively enrolled asymptomatic persons who underwent colonoscopy and immunochemical FOBT.

RESULTS

The sensitivity to adenomas </=9 mm was significantly higher than the false-positive rate as revealed by analysis of all eligible subjects (7.0%vs 4.5%, P < 0.001). In men, the sensitivity was superior to the false-positive rate and increased with age (<50 yr 6.1% and >60 yr 11.3%). On the other hand, the sensitivity in women was not significantly different from the false-positive rate in any generation (5.1%vs 4.7% for all eligible women, P= 0.72).

CONCLUSIONS

Immunochemical FOBT detected a small percentage of small adenomas in men at a rate that is significantly higher than the false-positive rate. Studies comparing the guaiac and immunochemical FOBTs using the end point of CRC-related death are expected.

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.

Hyperplastic polyposis and the risk of colorectal cancer

PURPOSE

Hyperplastic polyps are usually considered to be an innocent finding with little or no potential to progress to colorectal cancer. However, recent literature suggests that some of these polyps may be morphologically and genetically distinct and lead to microsatellite unstable colorectal cancers. The purpose of this study was to define the cancer risk associated with hyperplastic polyposis.

METHODS

All patients with hyperplastic polyposis diagnosed by a single colorectal surgeon at a university hospital were followed prospectively. The diagnosis of hyperplastic polyposis was made by the presence of more than 20 hyperplastic polyps distributed throughout the colon and/or a hyperplastic polyp at least 1 cm in size in diameter in the right colon. Patient demographics, family history, size, location, and distribution of polyps and the development of colorectal cancer were noted.

RESULTS

Thirteen patients who met the criteria for hyperplastic polyposis were identified and followed prospectively. All of these patients had at least 30 polyps distributed throughout the colon, often > 100. Nine of 13 also had a hyperplastic polyp at least 1 cm in size, usually in the right colon. Of particular note, 7 of 13 patients (54 percent) were diagnosed with colorectal cancer during the study period. Four had cancer on initial diagnosis and three patients developed cancer despite frequent colonoscopic surveillance. Five of seven colorectal cancers were located in the right colon.

CONCLUSIONS

Patients with hyperplastic polyposis are at high risk for colorectal cancer. Failure to identify this subset of patients could have dire consequences.

The anatomical distribution of colorectal polyps at colonoscopy

BACKGROUND

Colorectal carcinoma is one of the most common causes of cancer-related deaths in Australia. The distribution of polyps in the colon may effect the efficacy of a screening modality. The aim of this study was to determine the age-matched anatomic location and histologic type of colorectal polyps observed at colonoscopy over a 10-year period at our endoscopy unit.

STUDY

Endoscopy reports on 2,578 patients were reviewed; polyp/lesion histology and location (left, right, or both) were determined in 2,553.

RESULTS

Of all polyps observed, 1,310 (51%) cases were left-sided, 510 (20%) were right-sided, and 733 (29%) were synchronous. Adenomas were present in 1,659 cases (65%); of these, 734 (44%) were left-sided only and 405 (24.5%) were right-sided only. Carcinoma was observed in 189 (7%) cases, of which 71 (37.5%) were left-sided only. There was an increased right-sided prevalence of adenoma or carcinoma with age (p = 0.0029).

CONCLUSION

This was not a screening study, but it has shown that a significant number of adenomas and carcinomas lie proximal to the splenic flexure. Thus, in the absence of left-sided lesions, it is expected that examination of the colon limited to the splenic flexure would miss 23% of such lesions. The increasing right-sided prevalence of these lesions with age suggests that evaluation of the proximal bowel is particularly important in older people.

Pathology of colorectal cancer

The earliest phases of colorectal tumourigenesis initiate in the normal mucosa, with a generalised disorder of cell replication, and with the appearance of clusters of enlarged crypts (aberrant crypts) showing proliferative, biochemical and biomolecular abnormalities. The large majority of colorectal malignancies develop from adenomatous polyps. These can be defined as well demarcated masses of epithelial dysplasia, with uncontrolled crypt cell division. An adenoma can be considered malignant when neoplastic cells pass through the muscularis mucosae and infiltrate the submucosa. Definitions like "carcinoma in situ" or "intramucosal carcinoma" should be abandoned, since they lead to confusion. Although several lines of evidence indicate that carcinomas usually originate from pre-existing adenomas, this does not imply that all polyps undergo malignant changes, and does not exclude "de novo" carcinogenesis. Besides adenomas, other types of polypoid lesions include hyperplastic polyps (showing elongated crypts often with cystic dilatation), serrated adenomas (with a serrated glandular pattern], flat adenomas (flat lesions which are difficult to detect in routine lower endoscopy, but may possess malignant potential), hamartomatous polyps (which show a complex branching pattern of smooth muscle supporting normal lamina propria and glands), and inflammatory polyps. Colorectal carcinomas are one of the most frequent neoplasms in Western society; the macroscopic appearance of these lesions may be that of a polypoid vegetating mass or of a flat infiltrating lesion. Most of these tumours are adenocarcinomas (96%), that, in some cases, show a mucinous component. More rare malignancies of the large bowel include signet-ring cell carcinoma, squamous carcinoma, undifferentiated neoplasms and medullary type adenocarcinoma (solid carcinoma with minimal glandular differentiation or slight cellular pleomorphism). Colorectal carcinoma can be graded into well, moderately and poorly differentiated lesions; there is little evidence, however, that grading may be of help in evaluating prognosis of affected patients. In conclusion, colorectal tumours cover a wide range of premalignant and malignant lesions, many of which can easily be removed at endoscopy. It follows that colorectal neoplasms might be prevented by interfering with the various steps of carcinogenesis, which begins with uncontrolled epithelial cell replication, continues with the formation of adenomas of various dimensions, and eventually evolves into malignancy.

Adenoma characteristics as risk factors for recurrence of advanced adenomas

BACKGROUND AND AIMS

The link between adenoma characteristics at baseline colonoscopy and adenoma recurrence is poorly understood. We assessed whether the number, size, location, or histology of resected adenomas was related to the probability of recurrence of advanced lesions.

METHODS

Analyses were based on 1287 men and women in the wheat bran fiber (WBF) study, a randomized, double-blind trial of WBF as a means of decreasing the probability of adenoma recurrence over a period of 3 years. Multiple logistic regression was used to calculate odds ratios (ORs) and 95% confidence intervals (CIs).

RESULTS

Recurrence of advanced adenomas (>1 cm or tubulovillous/villous histology) was higher among individuals with adenomas >1 cm compared with those with adenomas <0.5 cm (OR, 2.69; 95% CI, 1.34-5.42) and among those with proximal than those with distal adenomas (OR, 1.65; 95% CI, 1.02-2.67). No association was observed for adenoma number or histology. A shift in location from the distal colon and rectum at baseline (54.6%) to more proximal recurrent adenomas (45.2%), including advanced lesions (42.8%), was observed.

CONCLUSIONS

Large or proximally located adenomas are important indicators of recurrence of advanced lesions. Because most recurrences were detected in the proximal colon, careful surveillance of this area is warranted.

Cost-utility of one-time colonoscopic screening for colorectal cancer at various ages

OBJECTIVE

One-time colonoscopy has been recommended as a possible colorectal cancer (CRC) screening strategy. Because the incidence of colorectal neoplasia increases with age, the effectiveness and cost of this strategy depend on the age at which screening occurs. The purpose of this study was to investigate the age-dependent cost-utility of one-time colonoscopic screening.

METHODS

We constructed a computer simulation model of the natural history of colorectal neoplasia. This model was used to compare the cost-utility of no screening and age-based strategies employing one-time colonoscopic screening (age ranges evaluated: 45-49, 50-54, 55-59, and 60-64 yr).

RESULTS

We determined that one-time colonoscopic screening in men age <60 yr and in women age <65 yr dominates never screening and screening at older ages. For both sexes, one-time colonoscopic screening between 50 and 54 yr of age is associated with a marginal cost-utility of less than $10,000 per additional quality-adjusted life-year compared to screening between 55 and 60 yr of age. One-time colonoscopic screening between 45 and 49 yr of age is either dominated (women) or associated with a marginal cost-utility of $69,000/per quality-adjusted life-year (men) compared to screening between 50 and 54 yr of age. The marginal cost-utility of one-time colonoscopic screening is relatively insensitive to plausible changes in the cost of colonoscopy, the cost of CRC treatment, the sensitivity of colonoscopy for colorectal neoplasia, the utility values representing the morbidity associated with the CRC-related health states, and the discount rate.

CONCLUSIONS

One-time colonoscopic screening between 50 and 54 yr of age is cost-effective compared to no screening and screening at older ages in both men and women. Screening in men between 45 and 49 yr of age may be cost-effective compared to screening between 50 and 54 yr of age depending on societal willingness to pay.

Hyperplastic-adenomatous polyposis syndrome

BACKGROUND

Although the syndrome of familial adenomatous polyposis is well known, sporadic patients with multiple polyposis are rare. There are no known syndromes associated with hyperplastic polyposis. In our search of the English surgical literature, we find no reference to a hyperplastic-adenomatous polyposis syndrome.

STUDY DESIGN

Over a 3-year period, we identified six patients ages 41 to 75 (mean age 61) with 50 to 100 hyperplastic polyps associated with adenomas.

RESULTS

Most of the hyperplastic polyps were found in the left colon and the largest ranged in size from 6 mm to 18 mm. The larger polyps were clinically indistinguishable from adenomas. Three of our six patients had invasive cancer of the proximal colon. All tumors were confined to the bowel wall. There was a family history of colon cancer in only one patient and no family history of polyposis.

CONCLUSION

These patients differ from previously described patients with polyposis syndromes; hyperplastic-adenomatous polyposis syndrome (HAPS) occurs in an older population with no family history of polyposis, has fewer polyps, most of which are hyperplastic, and is strongly associated with adenocarcinoma of the colon. In this series, we describe a previously unreported hyperplastic-adenomatous polyposis syndrome.

Initial management and follow-up surveillance of patients with colorectal adenomas

The clinical management of patients with adenomas is interesting because of the adenomas' malignant potential, the availability of effective intervention by colonoscopy, and the increasing number of patients having adenomas detected and removed. The current literature on follow-up surveillance is reviewed, and surveillance intervals are suggested based on data from the National Polyp Study. Patients newly diagnosed with three or more adenomas, an adenoma of more than 0.5 cm, or with a family history of colorectal cancer should have surveillance colonoscopy at 3 years following the polypectomy. Surveillance of patients with single, small tubular adenomas can be extended to 5 or more years. Patients with large sessile or malignant adenomas need to have follow-up earlier. Identification and removal of adenomatous polyps have been shown to reduce colorectal cancer incidence.

Importance of adenomas 5 mm or less in diameter that are detected by sigmoidoscopy

BACKGROUND

The need for colonoscopy in patients with adenomas 5 mm or less in diameter that are detected by sigmoidoscopy is controversial.

METHODS

We prospectively determined the prevalence of proximal colonic neoplasms in asymptomatic patients at average risk for colorectal cancer, each of whose index lesion on screening fiberoptic sigmoidoscopy was a benign adenoma. Polyps found on sigmoidoscopy underwent biopsy, and colonoscopy was recommended to all patients with neoplastic polyps. Rectosigmoid adenomas were classified as diminutive (< or = 5 mm in diameter), small (6 to 10 mm in diameter), or large (> or = 11 mm in diameter).

RESULTS

Of 3496 consecutive patients referred for sigmoidoscopy, 311 had neoplastic rectosigmoid polyps; 108 of these patients were excluded from the analysis because of a history of colonic neoplasia, symptoms, prior colonic evaluation, or incomplete follow-up data. The remaining 203 patients made up the study group, and all underwent colonoscopy. Neoplasms were found in the proximal colon in 40 of 137 patients (29 percent) with diminutive index polyps, 15 of 52 patients (29 percent) with small index polyps, and 8 of 14 patients (57 percent) with large index polyps. Advanced neoplasms (adenomas > or = 10 mm in diameter, adenomas with a villous component or moderate-to-severe dysplasia, carcinoma in situ, or frank carcinoma) were found in 8 patients (6 percent), 5 patients (10 percent), and 4 patients (29 percent), respectively. Two patients with diminutive index polyps had proximal carcinoma in situ, and two had proximal stage I carcinomas; one patient with a large index polyp had proximal stage III carcinoma.

CONCLUSIONS

The substantial prevalence of proximal colonic neoplasms, including advanced lesions, in asymptomatic average-risk patients with rectosigmoid adenomas < or = 5 mm in diameter warrants colonoscopy in these patients.

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.

Precursors of colorectal carcinoma. Biopsy and biologic markers

The term biologic marker (biomarker) of colorectal cancer refers in this article to an early preclinical phenotypic characteristic that relates to the risk for developing this cancer. Putative biologic markers in the normal colorectal mucosa of patients at risk include abnormal cell proliferation as determined by kinetic studies, ornithine decarboxylase activity, and polyamine synthesis. Alterations of mucin synthesis have been studied using both histochemical stains and lectin-binding techniques. Blood group and related carbohydrate antigens also have been evaluated as potential biomarkers in the normal mucosa. Biopsy small (less than 5 mm) polyps encountered at endoscopy has become a standard practice. Although a small polyp found to be an adenoma has a low likelihood of harboring high-grade dysplasia or invasive carcinoma, it represents an indicator of risk for colorectal neoplasia. Hyperplastic polyps, however, even though they have certain epidemiologic associations with colorectal neoplasia, are controversial as putative biomarkers of clinical relevance. Current research supports a concept of a field defect of the colorectal mucosa at risk for neoplasia, which may be identified by phenotypic abnormalities of the normal mucosa and the development of small adenomas.

Cigarette smoking, alcohol use and adenomatous polyps of the sigmoid colon

The relationship of adenomatous polyps of the sigmoid colon with cigarette smoking and alcohol use was investigated in male self-defense officials in Japan. In the comparison between 116 cases and 930 controls, total ethanol intake was not at all associated with the risk of adenomatous polyps, but cigarette smoking was strongly related to adenomatous polyps. After adjustment for total ethanol intake, body mass index and rank, odds ratios (and 95% confidence interval) for the categories of 0, 1-399, 400-799, and 800 or more cigarette-years were 1.0 (referent), 2.3 (1.1-4.6), 2.9 (1.5-5.4) and 3.2 (1.6-6.5), respectively. Among five alcoholic beverages (sake, shochu, beer, whiskey including brandy, and wine), only whiskey consumption was weakly related to the risk of adenomatous polyps. Because the present findings disagree with an earlier observation on self-defense officials, we examined the association with smoking and alcohol use separately for small (less than 5 mm) and large (greater than or equal to 5 mm) adenomas, combining data from these two studies. Cigarette smoking was more strongly associated with small adenomas while the positive association with certain alcoholic beverages were largely confined to large adenomas. These findings suggest that cigarette smoking and alcohol use may be linked with the development of adenoma at different stages of colon tumorigenesis.

Ethnic differences in the anatomical location of colorectal adenomatous polyps

The ratio of right- to left-sided colonic cancer is increasing, but data on the distribution of its usual precursor lesion, the colorectal adenoma, are contradictory. Therefore, we investigated the prevalence of right- and left-sided colorectal adenomatous polyps from January 1, 1970, to September 30, 1989, using the study design of "epidemiologic necropsy" and the autopsy files of The Johns Hopkins Hospital. Compared with the decade of the 1970's, the 1980's showed a slight decrease in the overall prevalence of right-sided adenomas (6.4 per 1,000, 95% confidence limits 4.7-8.8 vs. 5.1 per 1,000, 95% CL 3.6-6.5), but a marked decrease occurred in left-sided adenomas (11.8 per 1,000, 95% CL 9.3-14.3 vs. 6.7 per 1,000, 95% CL 4.8-8.6). As a result, the ratio of right-sided to left-sided adenomas increased from 0.55 in the 1970's to 0.77 in the 1980's. This increased ratio occurred in both sexes, although prevalences were lower in females, and in whites. Unexpectedly, blacks had a ratio of right-sided to left-sided adenomas greater than unity in both the 1970's and 1980's (1.19 vs. 1.79) due to a relatively high prevalence of right-sided adenomas (5.8 per 1,000, 95% CL 3.6-8.0 in 1970's; 5.8 per 1,000, 95% CL 3.3-8.3 in 1980's), but low prevalences of left-sided adenomas (4.9 per 1,000, 95% CL 3.0-6.8 in 1970's; 3.2 per 1,000, 95% CL 1.2-5.2 in 1980's). The overall adenoma prevalence in blacks was lower than in whites. We conclude that the right-sided predominance of colorectal adenomas in blacks suggests ethnic differences in the pathogenesis of colorectal adenomas. This observation may have important implications for secondary prevention of colorectal cancer.

Flexible sigmoidoscopy may be ineffective for secondary prevention of colorectal cancer in asymptomatic, average-risk men

Asymptomatic men (N = 114) 50 years of age or older had screening for colorectal neoplasia with flexible sigmoidoscopy followed by colonoscopy regardless of the sigmoidoscopic result. Our study objective was to determine the prevalence of patients having isolated adenomatous polyps in a proximal colonic segment in the absence of a distal index neoplasm within reach of the sigmoidoscope. Through the combined use of sigmoidoscopy and colonoscopy, adenomatous polyps were detected in 47 of 114 individuals (41%). A total of 88 adenomas was found. Seventeen patients had isolated neoplasms in proximal colonic segments in the absence of distal adenomas. These patients represented 15% of screened subjects (17 of 114) and 20% of individuals who lacked adenomas on sigmoidoscopy (17 of 84). The majority of proximal neoplasms were small (less than 1.0 cm), tubular adenomas. Flexible sigmoidoscopy may be ineffective for screening asymptomatic men for neoplasia. However, it remains to be determined if a 20% miss rate (for those with a normal sigmoidoscopic examination) is significant and whether small proximal adenomas are worth finding.

Solitary and synchronous adenomas of the colon and rectum: comparison of malignancy parameters

The histological, mucin histochemical and immunohistochemical features were evaluated of 74 solitary and 73 synchronous colorectal adenomas which were endoscopically removed from 124 patients. Of the patients, 60% had a single adenoma, whereas 40% had at least two adenomas in their colorectum. Comparing the incidence of synchronous adenomas in both sexes revealed a statistically significant higher incidence (P less than 0.005) in males. The localization of the solitary and synchronous adenomas in the large bowel was similar. Moreover, parameters of malignant change within the adenomas (size, predominant type of mucosal growth and degree of dysplasia-with the exception of severe dysplasia) as well as signs of dedifferentiation (relative proportions of goblet and columnar cells) were also similar. Mucin staining intensities (periodic acid-Schiff, high iron diamine and alcian blue) and the immunoreactivity patterns of secretory component and carcinoembryonic antigen, both cytoplasmic and on the surface of the epithelial cells, were also identical in both groups of adenomas. Thus, neither the routine histological nor the mucin- and immunohistochemical features differed between the groups, except for severe dysplasia. It is concluded that there is no inherent difference in malignant potential between solitary and synchronous adenomas, with the possible exception of the degree of dysplasia.

Colonoscopic screening of asymptomatic patients with a family history of colon cancer

The records of 201 asymptomatic patients who underwent colonoscopy based solely on a family history of colon cancer were reviewed. Eighty-five patients (42 percent) had a total of 166 lesions. Fifty-four (27 percent) patients of the screened population had neoplastic lesions, while 31 (15 percent) patients had nonneoplastic polyps. Four carcinomas were found. Twenty-five of the patients with polyps (29 percent) had no polyps distal to the splenic flexure; these proximal polyps (and two carcinomas) would have been missed on screening with fiberoptic sigmoidoscopy. Nineteen of these 25 patients had polyps smaller than 0.5 cm, which likely would have been missed with contrast enemas. Almost one half (47 percent) of all polyps discovered at screening colonoscopy were proximal to the descending colon. Only one patient younger than 40 years old had adenomas. The yield of polyps and cancer in patients with familial risk indicates screening colonoscopy should be considered after age 40.

A comparative case-control study of colorectal cancer and adenoma

We conducted a comparative case-control study of colorectal cancer and adenoma involving 221 cases with colorectal cancer, 525 cases with colorectal adenoma and 578 neighborhood controls. Daily vegetables intake was associated with lower risks of distal colon adenoma (relative risks (RR) = 0.59, 95% confidence interval (CI): 0.39-0.89) and rectal cancer (RR = 0.46, 95% CI: 0.25-0.84). Daily beans intake was associated with lower risk of colon adenoma (RR = 0.58, 95% CI: 0.37-0.91 for the proximal colon and RR = 0.63, 95% CI: 0.45-0.88 for the distal colon) and daily intake of seaweeds was associated with lower risk of rectal cancer (RR = 0.42, 95% CI: 0.22-0.82). Daily intake of fish and shellfish also showed an inverse association with the risk of colon adenoma (RR = 0.67, 95% CI: 0.45-0.99 for the proximal colon and RR = 0.70, 0.52-0.94 for the distal colon). Generally, intakes of animal or vegetable fat-rich foods, especially meats, were associated with decreases in risks of both adenoma and cancer, though the association of cancer was not statistically significant. Other than dietary factors, daily alcohol drinking was associated with an increased risk of adenoma in the proximal colon (RR = 1.95, 95% CI: 1.15-3.29) and ex-drinkers showed higher risks for colon adenoma and colorectal cancer. Sports or occupational activities and coffee drinking were inversely associated and family history of colorectal cancer was positively associated with the risk of both colorectal adenoma and cancer.

Colorectal polyps in an Australian population. A histological and immunohistochemical study

The histology and immunohistochemistry of 896 polyps and other focal epithelial abnormalities detected macroscopically in 86 surgical resections from patients with colorectal adenocarcinoma and benign bowel disorders were studied. The lesions identified included 177 adenomas, 387 hyperplastic (metaplastic) polyps, and 202 non-neoplastic polyps designated 'focal cryptal hyperplasia'. Numbers of both neoplastic and non-neoplastic polyps were significantly increased in resections for carcinoma, with 72 per cent of all polyps in right and 10 per cent in left hemicolectomy specimens being neoplastic. Thirty per cent of adenomas were less than 2 mm in diameter and 6 per cent larger than 10 mm. Observations on polyp size, number, distribution, histological appearance, and antigenic composition suggested that focal cryptal hyperplasia evolves into the hyperplastic polyp. In doing so, there is loss of expression of a tissue specific antigen. Hyperplastic polyps were significantly larger in colons with adenoma than in those without.

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.

Spatial clustering of multiple hyperplastic, adenomatous, and malignant colonic polyps in individual patients

Analysis of relative polyp locations in 426 consecutive patients with multiple colonic polyps found on colonoscopy showed novel findings. First, synchronous and metachronous neoplastic polyps showed spatial clustering in individual patients. For example, patients with their largest neoplasm in the cecum or proximal ascending colon, had 34.3 percent +/- 4.6 percent (standard error) of their other colonic neoplasms in the same location. Second, hyperplastic polyps showed spatial clustering in individuals that was statistically significantly greater than expected from the increased hyperplastic polyp concentration in the rectum and sigmoid. Third, hyperplastic polyps showed spatial clustering with neoplastic polyps; this clustering was similar in magnitude to clustering for exclusively hyperplastic or neoplastic polyps. In contrast, lipomas were not spatially clustered with hyperplastic and neoplastic polyps. The magnitude of clustering between hyperplasia and neoplasia showed a closer association between these histologic types than previously appreciated. Because of clustering, regions with prior polyps appear to merit closer surveillance. These findings suggest clinical study, using a randomized controlled clinical trial, of whether a patient who had only rectal and sigmoid adenomas on initial and follow-up colonoscopy should have surveillance with flexible sigmoidoscopy alternating annually with colonoscopy. A patient with a prior cecal adenoma should have surveillance only with a complete colonoscopy or adequate cecal views on barium enema.

Association of colonic diverticula with adenomas and carcinomas. A colonoscopic experience

A case control study of 150 individuals with colonic symptoms and diverticular disease diagnosed by total colonoscopy was performed to ascertain whether adenomas and carcinomas are detected with a higher frequency in these patients than in matched controls with symptoms but not diverticular disease. Adenomas and carcinomas were seen in 36 percent of the patients and in 17 percent of the controls (P less than .001); the overall odds ratio was calculated to be 3.0 (95 percent confidence interval +/- 1.8). When examined separately, adenomas maintained their significantly higher frequency (27 vs. 10 percent, P less than .001), while no difference was observed as regards carcinomas (9 vs. 7 percent). The odds ratios for adenomas and carcinomas were calculated to be 3.5 +/- 2.5 and 1.4 +/- 1.4, respectively. From the fifth to eighth decades there was a fourfold increase in premalignant and malignant lesions in the patient group and a twofold increase in controls. With relation to sex, a statistically significant difference was reached in men but not in women in the sample examined. These data show that symptomatic patients with colonic diverticula have more frequent adenomas, but not carcinomas, than symptomatic control matched by sex and age.

Colorectal adenomas in a tropical country

The objective of this study was to demonstrate the existence of colorectal adenomas in India and compare the findings with those reported elsewhere. Seventeen (2.06 percent) adenomas were detected among the 824 colonoscopic examinations conducted from 1978 to 1987. Synchronous malignant tumors were present in 3 (17.6 percent) of the 17 patients. Thus, though adenomas exist in India, they are relatively uncommon to western countries.

Family history of colorectal cancer as a risk factor for benign and malignant tumours of the large bowel. A case-control study

The relationship between first degree family history of colorectal cancer and the risk of benign or malignant tumours of the large bowel was investigated in a case-control study. Two groups of cases (283 patients with adenomatous polyps and 414 patients with adenocarcinoma of the large bowel) and 2 groups of controls (399 polyp-free subjects and 456 hospitalized patients) were interviewed. Since no difference in the frequency of family history between the 2 control groups was detected, these were lumped together. A 3-fold increase in risk of adenomatous polyps in relatives of patients with colon cancer was observed (OR = 3.18, 95% CI 2.06-4.89). The relative risk of colorectal cancer among relatives of patients with adenocarcinoma was 2.36 (95% CI 1.54-3.60). No significant difference in the frequency of first degree relatives with a history of cancer of the large bowel was detected between patients with colorectal cancer and those with adenomatous polyps. When only history of colorectal cancer among parents was considered, the results closely paralleled those of the previous analysis.

Immunohistochemical study of epithelial cell proliferation in hyperplastic polyps, adenomas, and adenocarcinomas of the large bowel

A monoclonal antibody to bromodeoxyuridine was used in tissue specimens previously incubated with bromodeoxyuridine to show S-phase cells by immunohistochemical technique. Biopsy specimens of normal mucosa (n = 10), hyperplastic polyps (n = 10), adenomas with low-grade dysplasia (n = 20), adenomas with high-grade dysplasia (n = 10), and invasive adenocarcinomas (n = 10) of the large bowel were studied. Labeling index and cell proliferative patterns were analyzed. No statistically significant difference was found in labeling index between normal mucosa and hyperplastic polyps or between adenomas with high-grade dysplasia and adenocarcinomas. The labeling index was significantly lower in normal mucosa and in hyperplastic polyps than in adenomas and adenocarcinomas (p less than 0.001). The difference in labeling index between adenomas with high-grade dysplasia and low-grade dysplasia was also statistically significant (0.01 less than p less than 0.05). In normal mucosa and in hyperplastic polyps the proliferative zone was confined to the lower two-thirds of the crypt; no kinetic activity was found in the upper portions of the crypt or in surface epithelium. In adenomas the labeled cells were either present in the upper third or scattered along the whole axis of the crypt and in the surface epithelium. Labeling patterns in invasive carcinomas were similar to those observed in adenomas with high-grade dysplasia. The difference in proliferative patterns between hyperplastic polyps and adenomas supports a different significance of the two polypoid lesions in the histogenesis of large bowel cancer; our results confirm the subsequent steps of the adenoma-carcinoma sequence. Immunohistochemical labeling patterns observed with monoclonal antibody to bromodeoxyuridine in polypoid and cancer lesions of the large bowel are similar to those described by autoradiographic studies.

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.

Site-specific distribution of large-bowel adenomatous polyps. Emphasis on ethnic differences

The anatomic distribution of adenomatous polyps occurring in the large intestine of 98 consecutive patients was studied. Fifty-two of the patients were black and 46 were white. Seventy-nine percent of lesions in whites were found in the distal colon and rectum, whereas in blacks this occurred in only 47 percent. The difference was significant (P less than .01). Black patients also displayed a greater frequency of synchronous polyps and had a higher incidence of previous colorectal polyps. The findings suggest that the total colonic surveillance is essential in black patients to adequately screen for large-bowel neoplasia.

Colorectal polyps and diet: a case-control study in Marseilles

This study investigates the differences in usual past diet between 252 subjects with newly diagnosed adenomatous or villous polyps of the colon and rectum and a group of 238 hospital controls. Cases and controls were interviewed in hospital by 3 nutritionists using a dietary history questionnaire focused on the diet during the preceding year. Nutrient intake was estimated by means of ad hoc food tables adapted from French and British tables. Out of 16 food groups considered in the analyses, the cases reported lower consumption of oil and potatoes and higher consumption of sugar added to food and drink. Among nutrients, we found that cases had a lower consumption of carbohydrates (not taking into account added sugar), potassium, magnesium and vitamin B6. We found a slightly lower intake of fibre and a slightly higher intake of saturated fat among cases, though neither was statistically significant. Intake values for fibre and for carbohydrates were highly intercorrelated and, due to measurement errors, the effect of one may be masked by the other and vice versa. The hypothesis that some components of carbohydrates (starches, fibre and natural sugars but not added sugar) play a protective role in relation to the biology of tumours of the intestinal tract is considered in further multivariate analyses and in the "Discussion".

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.

The adenoma-carcinoma sequence of the colon and rectum

Morphological and epidemiological arguments in favour of an adenoma-carcinoma concept of evolution in the development of colorectal cancers are presented. It is highly probable that most colorectal cancers arise in adenomas. Therefore detection and endoscopic removal of adenomas is a means of reducing the incidence of colorectal carcinomas.