Colorectal polyps and carcinoma in Southern Iran

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.

Systematic Review of Prevalence, Risk Factors, and Risk for Metachronous Advanced Neoplasia in Patients With Young-Onset Colorectal Adenoma

BACKGROUND & AIMS

The incidence and mortality of early-onset colorectal cancer (CRC) are increasing. Adenoma detection, removal, and subsequent endoscopic surveillance might modify risk of CRC diagnosed before age 50 years (early-onset CRC). We conducted a systematic review of young-onset adenoma (YOA) prevalence, associated risk factors, and rate of metachronous advanced neoplasia after YOA diagnosis.

METHODS

We performed a systematic search of multiple electronic databases through February 12, 2019 and identified studies of individuals 18 to 49 years old that reported prevalence of adenoma, risk factors for adenoma, and/or risk for metachronous advanced neoplasia. Summary estimates were derived using random effects meta-analysis, when feasible.

RESULTS

The pooled overall prevalence of YOA was 9.0% (95% CI, 7.1%-11.4%), based on 24 studies comprising 23,142 individuals. On subgroup analysis, the pooled prevalence of YOA from autopsy studies was 3.9% (95% CI, 1.9%-7.6%), whereas the prevalence from colonoscopy studies was 10.7% (95% CI, 8.5%-13.5). Only advancing age was identified as a consistent risk factor for YOA, based on 4 studies comprising 78,880 individuals. Pooled rate of metachronous advanced neoplasia after baseline YOA diagnosis was 6.0% (95% CI, 4.1%-8.6%), based on 3 studies comprising 1493 individuals undergoing follow-up colonoscopy, with only 1 CRC case reported. Overall, few studies reported metachronous advanced neoplasia and no studies evaluated whether routine surveillance colonoscopy decreases risk of CRC.

CONCLUSIONS

In a systematic review, we estimated the prevalence of YOA to be 9% and to increase with age. Risk for metachronous advanced neoplasia after YOA diagnosis is estimated to be 6%. More research is needed to understand the prevalence, risk factors, and risk of CRC associated with YOA.

A Short Impact of Epidemiological Features of Colorectal Cancer in Iran

Aims and background

The incidence of colorectal cancer varies from one country to another although the variation is not much different in neighboring countries. Even in one country there is no relevant variation in incidence from one province to another. A study of different provinces in a vast developing country, Iran, was performed to determine the incidence of colorectal cancer.

Methods

Information from cancer registries of four provinces in the north, north-west and central-south of Iran regarding colorectal cancer was gathered for analysis. A total of 1628 cases with colorectal cancer in a total population of 6,435,549 was identified.

Results and conclusions

In all provinces, there were more male than female patients with colorectal cancer. The study also showed that the incidence of the disease in young patients was higher than expected. Except for Israel because of genetic factors, these provinces showed one of the highest ASR among Asian countries. This finding probably indicates more westernization in the Iranian diet with a genetic influence. Some social habits including dietary and tobacco smoking may also influence the incidence of colorectal cancer in the Iranian population. Community-related risk factors need further investigation, especially in the high-risk Northern part of the country.

Rising rates of colorectal cancer among younger Iranians: is diet to blame?

BACKGROUND

Colorectal cancer (crc) is one of the most prevalent cancers in the world. Although the incidence of crc is currently very low in the older Iranian population compared with Western populations, young Iranians show a rising trend of crc-that is, the age-adjusted rate is close in the young Iranian population compared with the U.S. population, and the rate in older Iranians is much lower.

METHODS

To assess a putative relationship between diet and a rising rate of crc in younger Iranians, a combined text word and mesh heading search strategy identified relevant studies through Google Scholar and medline.

RESULTS

A critical look at diet among Iranians shows major issues that might be raising the risk for crc. There are also scenarios other than diet for the rise, such as the young age structure of the country. However, the actual scenario is more complex.

CONCLUSIONS

In Iran, crc is one of the most common incident cancers and a common cause of cancer death. Primary and secondary prevention-with attention to a healthy lifestyle, physical activity, and screening-should be enhanced in the general population.

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.

Precancerous lesions in colorectal cancer

Colorectal cancer (CRC) is the third most common cause of cancer death in the world. The incidence rate (ASR) and age distribution of this disease differ between most of African-Middle-Eastern (AMAGE) and North America and Europe for many reasons. However, in all areas, "CRC" is considered as one of the most preventable cancers, because it might develop from variant processes like polyps and IBD in addition to the genetic pathogenesis which became very well known in this disease. We tried in this paper to review all the possible reasons of the differences in incidence and age between the west and AMAGE. Also we reviewed all the mutations that lead to the hereditary and familiar clustering of this disease with the correlations with the surrounding food and environment of different areas. Then, we focused on the precancerous pathology of this disease with special focusing on early detection depending on new endoscopy technology and most important genetic studies. We lastly reviewed the evidence of some of the surveillance and put suggestions about future surveillance programs and how important those programs are on the psychological aspect of the patients and their families.

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.

Occurrence of colorectal adenomas in younger adults: an epidemiologic necropsy study

BACKGROUND & AIMS

The colorectal adenoma is the precursor lesion in virtually all colorectal cancers. Occurrence of colorectal adenomas has been studied in older adults but analysis in younger adults is lacking.

METHODS

The prevalence by age, sex, race, and location, and the number of colorectal adenomas detected was investigated using epidemiologic necropsy in 3558 persons ages 20 to 89 autopsied from 1985 to 2004 at the Johns Hopkins Hospital. Results were standardized to the general population. Younger adults 20 to 49 years old were compared with older adults 50 to 89 years old.

RESULTS

The prevalence of colorectal adenomas in younger adults increased from 1.72% to 3.59% from the third to the fifth decade of life and then sharply increased after age 50. In younger adults, adenomas were more prevalent in men than in women (risk ratio, 1.09; 95% confidence interval, 1.07-1.11) and in whites than in blacks (risk ratio, 1.28; 95% confidence interval, 1.26-1.31). Overall, both younger and older adults had predominately left-sided adenomas, but blacks in both age groups had more right-sided adenomas. Occurrence of 2 or more adenomas in younger adults and 5 or more in older adults was greater than 2 SDs from the mean.

CONCLUSIONS

Colorectal adenomas infrequently occur in younger adults and are more prevalent in the left colon. Irrespective of age, blacks have more right-sided adenomas, suggesting the need for screening the entire colorectum. Two or more adenomas in younger adults and 5 or more in older adults represents polyp burden outside the normal expectation.

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.

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.

Incidence and age distribution of colorectal cancer in Iran: results of a population-based cancer registry

Epidemiologic patterns of colorectal cancer (CRC) in Iran have not been studied adequately. In a recent cancer registry and active cancer surveillance, we collected data on the incidence of colorectal tumors in five provinces of Iran from 1996 to 2000. In total, 2055 were registered in this study. Age-adjusted rates of CRC in Iranian males and females were 8.2 and 7.0/100,000, respectively. Seventeen percent of the cases were younger than 40 years of age at the time of diagnosis. This proportion was similar to proportions seen in many other Middle-Eastern countries, but much higher than those seen in Western countries. A comparison of age-specific rates between Iran and the US showed similar rates in young (<40 years) Iranians and Americans, but much lower rates in older (>/=40) Iranians. We conclude that Iran is still a country with low-risk of CRC, particularly for older individuals. The high proportions of young CRC cases seen in Iran, and probably many neighboring countries, are due to the young age-structure of these countries and relatively low rates of CRC in older individuals.

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.

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.

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.

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.

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

The study is based on a prospective survey of 200 necropsies, to determine the prevalence of colonic polyps and diverticula in Hong Kong. Adenomatous polyps were found in 34% of men and 19% of women. The corresponding figures for hyperplastic polyps were 22% and 15%. When compared with European countries having similar rates for colorectal cancer, the polyp pattern by type, prevalence, and distribution is very similar. For diverticula the prevalence rate in this study was only 5%; most of these were situated in the caecum. This is at marked variance to the European pattern.

Polyps and colorectal cancer in South African Blacks

This study reflects the fact that cancer of the large bowel is uncommon in South African Blacks, and that colorectal polyps do not appear to constitute a precursor to most colorectal cancers. Furthermore, it is shown that dietary factors associated with this cancer in Western populations are not evident in the Black population. In the South African White population, however, the disease behaves in a similar way to that observed in Western countries. Other definitive differences found were the absence of multiple synchronous cancers and diverticular disease in the Blacks with colorectal cancer. It is thus postulated that dietary factors are absent, or have not been present for a sufficient length of time to influence the development of polyps or polyp--cancer sequence in this population. It is also possible that the adenoma--carcinoma progression observed in Western countries may not be relevant to the development of all colorectal carcinomas in communities such as those reported here.

Colorectal cancer in Jordan and Nova Scotia: a comparative epidemiologic and histopathologic study

A comparative study of colorectal adenocarcinoma was undertaken among the populations of Jordan and Nova Scotia, Canada. The incidence of this cancer was 13 (colon 6, rectum 7) and 53 (colon 31, rectum 22) per 100,000 males aged 35--64 years, respectively. Colonic tumors (excluding rectosigmoid) showed left-sided preponderance in Jordanians and right-sided preponderance in Nova Scotians. Age average at diagnosis was 49 years in Jordanians (colon 47 years and rectum 50 years) and 66 years in Nova Scotians (colon 67 years and rectum 63 years), with peaks in the fifth and seventh decades and a male to female ratio of 1.3:1 and 1:1, respectively. The mucinous type accounted for 31 and 13% of colorectal adenocarcinomas in Jordanians and Nova Scotians, respectively, of which the signet-cell type accounted for 14 and 2% of the total number, respectively. The actual incidence rate of mucinous carcinoma, however, was higher among Nova Scotians. In both groups, mucinous carcinoma showed predilection for females and rectal signet-cell carcinoma showed bias toward younger females. The authors believe that the significantly different epidemiologic and morphologic features of colorectal cancer demonstrated in these two communities could shed light on possible etiologic influences, such as dietary habits or other environmental factors.

Studies on the difference of background mucosa among single advanced carcinoma and benign diseases of the large intestine, and familial polyposis coli

The entire lengths of fixed specimens from 17 single advanced carcinomas of the colon (Cancer Group), four benign lesions (Benign Group), and four familial polyposis coli (Polyposis Group) were step-sectioned. It was found that the tubules of the basal cells were densely packed with rather a small number of goblet cells in the cancer and benign lesion specimens, but clear and loose with completely differentiated goblet cells in the polyposis coli specimens. Microscopic adenomas that were macroscopically unrecognizable and only microscopically detectable were found in 16 lesions in the Cancer Group, one lesion in the Benign Group, and in numerous lesions in the Polyposis Group. All of them developed from the basal cells. These findings indicate that the colonic mucosa of patients in the Cancer and Benign Groups is similar, but differs from that of the Polyposisis Group, and that microscopic adenomas are not uncommon in the Non-Polyposis Groups (Cancer and Benign Groups), findings which were not previously known.

Polyps of the large intestine in Northern Norway

In unselected autopsies on 171 males and 109 females over 20 years of age in Tromsø, Northern Norway, adenomas of the colon and rectum were present in 40% of the males and 33% of the females. The frequency of adenomas increased with age in both sexes. Hyperplastic polyps were found in 20% of all cases with no variation in frequency with sex or age. Before the age of 65 most adenomas were located in the distal half of the large intestine in both sexes. After 65 years in males and 75 years in females the predilection site was shifted to the proximal half of the large intestine. The average size and grade of atypia of adenomas increased with age, but no significant difference in grade of atypia was found between the proximal and distal halves of the large intestine. The occurrence of adenomas was not associated with any of the common chronic diseases thought to be related to a western-style diet or to malignant or benign neoplasms elsewhere in the body. A significant association was found between the occurrence of adenoma and high body weight. The findings support the role of adenomas as precursors of colorectal carcinoma.

Cancer and "cancer related" colorectal lesions in São Paulo, Brazil

A series of 832 necropsy specimens were studied grossly with a magnifying lens and all lesions identified were studied microscopically. The age and sex-specific prevalence of adenomatous and hyperplastic polyps is reported and results are compared with those of other populations. A correlation was made between polyps and cancer of the colon and rectum (407 cases). The data suggest that São Paulo is a community in a transitional stage between intermediate and high risk of cancer of the colon. The epidemiologic characteristics of lower rectum cancer are peculiar to some populations and appear unrelated to colon cancer. The black population of São Paulo has a higher prevalence than that reported for African negroes. The data also implicate adenomatous polyps, diverticulosis and hemorrhoids as being probably related diseases.

Aetiology of adenoma--carcinoma sequence in large bowel

A hypothesis, based on epidemiological and histopathological data, is proposed to account for the aetiology of colorectal adenomas and carcinomas. Adenomas are initially caused by an environmental agent which acts on the colorectal cells of adenoma-prone persons, a further environmental agent causes small adenomas to grow, and a carcinogen causes malignancy in a high proportion of large adenomas.