Treatment of small colorectal polyps: a population-based study of the risk of subsequent carcinoma

We conducted a retrospective cohort study of 751 residents of Rochester, Minnesota, whose small (1 cm or less) colorectal polyps had been treated without biopsy. Eighteen colorectal carcinomas were found in this group in the course of more than 10,000 person-years of follow-up, whereas 15.27 cases were expected (relative risk, 1.2). The overall rate for the development of cancer and the relative risks for various subgroups of the cohort were not significantly elevated, and survival in this cohort was not impaired. We conclude that fulguration of selected small colorectal polyps without prior biopsy does not subject patients to an unusual risk for development of colorectal carcinoma. Customary periodic medical examination should suffice for patients with these lesions.

[An epidemiological study on familial predisposition to large bowel cancer]

To investigate hereditary factors in large bowel cancer, we studied the clinical characteristics of familial predisposed patients. The hospital records of 937 male and female patients, excluding those with familial polyposis coli, seen at the Cancer Institute Hospital, Tokyo between 1964-1979 were reviewed. The cases were grouped by sites and multiplicity of the tumors. A total of 96 patients (6%) had one or more relatives with colo-rectal cancer. The frequency of familial occurrence was highest (20%) for multiple cancers and lowest (4%) for rectal cancer. The average age at surgery was 55.3 years in familial patients and 56.9 years in non-familial patients. The lower age at surgery in familial compared to non-familial patients was significant for multiple cancers and remarkable, though not significant, for proximal colon cancer and double primary cancers. We posit that the hereditary type of large bowel cancer may be characterized by familial, early age at onset, proximity and multiplicity of the intestinal tumor, and double primary cancers in other organs. While polyp formation seems to be largely affected by environmental factors, its occurrence may be enhanced by hereditary factor.

The multihit model of carcinogenesis: etiologic implications for colon cancer

A new multihit model of carcinogenesis is developed for use in evaluating age-specific cancer incidence rates in human populations. The model allows for some heterogeneity in both risk (perhaps genetic) and pathway (number of hits). Fitting the model yields estimates of (1) levels of effect of background exposure to environmental agents, (2) tumor growth times after initiation of a malignant cell, and (3) relative sizes of high-risk groups in a human population. Maximum likelihood procedures are used to fit the model to the polyposis coli data of Veale and the colon cancer incidence data from the Third National Cancer Survey. Model estimates may be verified in some cases by review of independent data in the literature and results have both theoretical and practical implications. Findings are generally consistent with the adenoma-carcinoma etiologic sequence postulated by Hill, Morson and Bussey with one exception. A large proportion of the population may be at risk of four-hit colon tumors following a non-adenoma etiologic sequence.

Skin fibroblasts from humans predisposed to colon cancer are not abnormally sensitive to DNA damaging agents

We report here that skin fibroblasts from individuals with hereditary adenomatosis of the colon and rectum (ACR), an autosomal dominant trait, were not abnormally sensitive to x-rays, UV-light or MNNG. ACR cells were also competent in restoring x-rays and UV-light induced damage of SV40 T-antigen expression following infection of these cells by the irradiated virus. We concluded, therefore, that sensitivity to x-rays, UV-light and MNNG can not be used to identify gene-carriers dominantly predisposed to colon cancer.

Fiberoptic colonoscopy. A report of findings in 481 patients from Kuwait

The authors report 481 colonoscopic examinations, performed in the Amiri Hospital, Kuwait. The objective of this paper is to demonstrate the pattern of colonic diseases in this region and to compare our findings with those reported from elsewhere. Although these are preliminary results, they suggest that colonic diseases, in general, are uncommon in this area. Ulcerative colitis was the most common pathology detected on colonoscopy. Polyps and diverticulosis were less common than those observed in the west. The frequency of Crohn's disease in Indians and Pakistanis in Kuwait was found to be high, although it is reported to be a very rare disease in their native countries.

Polyps and cancer of the large bowel: a necropsy study in Liverpool

In a prospective necropsy study of the large bowel in 365 cases, the commonest polyp identified was the hyperplastic (metaplastic) variety, of which 86.1% of the total were located in the rectum. The other main type of polyp found, and of much greater importance because of its malignant potential, was the neoplastic adenoma. These were present, either singly or multiply, in 73 of 198 male cases (36.9%) and in 48 of 167 female cases (28.7%). Their prevalence and their tendency to be multiple rose with increasing age in both sexes. Most adenomas had a tubular growth pattern and 88.8% of these were under 1 cm in diameter. There was a fairly even distribution of adenomas throughout the large bowel but a higher proportion of adenomas over 1 cm in diameter occurred in the caecum, sigmoid colon, and rectum than at other sites. In the whole series nine adenocarcinomas were present, two of which were arising in adenomas.

Large bowel diseases in New Zealand based on 1118 air contrast enemas

Colorectal disorders were analysed from a radiology practice, where specific data were indexed at the time of each examination. Among 1118 consecutive adults examined by air contrast barium enema, 49 were found to have colorectal cancer, 49 polyps, 35 inflammatory bowel disease and 395 diverticular disease. The 267 patients under the age of 40 showed no carcinoma, two with polyps, 18 with inflammatory bowel disease and 16 with one or more diverticula. Carcinoma, polyp, and inflammatory bowel disease were detected no more frequently in patients with diverticular disease than without. Complicated diverticular disease was rare. An analysis of specific symptoms with uncomplicated diverticular disease showed patterns of bowel habit, pain or bleeding, no different from patients with negative barium enemas. Of the 44 colon carcinomas, 28 were located in the sigmoid; bleeding was the major presenting symptom in 11, while two others were anaemic. The importance of sigmoidoscopy in assessing abdominal symptoms and rectal bleeding is stressed, along with the need for radiology in patients over, rather than under, 40 years of age.

Surgical experience with carcinoma of the colon and rectum

From September 1925 through December 1978 at Vanderbilt University Hospital, 1,279 patients with adenocarcinoma of the colon and rectum underwent operations. Reports of this cumulative series have been published previously; the last report in 1970 included 1,022 patients. The current report examines the progress made in our recognition and management of colorectal cancer. During this 54-year period, there has been a relative decrease in the incidence of carcinoma of the rectum and a relative increase in carcinomas elsewhere in large bowel. Resectability rate has steadily increased, culminating in a rate of 98.4% in the recent period (1969-1978). The operative mortality rate fell to 4.3% (1956-1960) but has shown a slight rise to 5.4% in the recent period (1969-1978). This reflects the increased number of patients in the eighth to the tenth decades of life. Five-year survival rates in 99% of 1,218 patients were computed. Absolute five-year survival for the recent period was 43.7%, compared with 17% for the initial period. Five-year survival rates for patients in the recent decade with Dukes A, B, and C lesions were 67%, 58.6%, and 33.3%, respectively. Comparison of survival data in the last two decades shows little improvement. However, in the last 20 years, 78 to 80% of patients had more advanced lesions.

The prevalence of polyps of the large intestine in Oslo: an autopsy study

The colon and rectum were removed from 445 consecutive autopsies and examined for the presence of polypoid lesions under an illuminating magnifying lens. There were seven clinically undiagnosed carcinomas, 329 adenomas, 174 hyperplastic polyps, 59 mucosal tags, 34 other polypoid lesions, and 54 polyps in which no histologic diagnosis could be made. Adenomas were present in 34% of the men and 32% of the women. The adenoma prevalence rate increased smoothly with age in men, whereas the rate in women showed a biphasic variation with a peak at 50--59 years followed by a second increase after 70 years of age. The distribution of adenomas within the bowel showed a marked change with age, from a moderate left-sided predominance before 60 years of age to a marked right-sided predominance in patients over 80 years of age, particularly in men. Hyperplastic polyps were present in 27% of the men and 18% of the women. In men, their frequency and distribution within the bowel showed similar changes with age as were seen for the adenomas. In women, no such age-dependency was observed for hyperplastic polyps. Multiplicity of polyps increased with age and was more pronounced in men than in women. Adenomas in women tended to be larger, more atypical, and more villous than in men. A comparison with a similar study from Northern Norway showed no difference in the prevalence of adenomas in spite of a 70% higher incidence rate for colorectal cancer in Oslo.

The prevalence of polyps of the large intestine in Oslo: an autopsy study

The colon and rectum were removed from 445 consecutive autopsies and examined for the presence of polypoid lesions under an illuminating magnifying lens. There were seven clinically undiagnosed carcinomas, 329 adenomas, 174 hyperplastic polyps, 59 mucosal tags, 34 other polypoid lesions, and 54 polyps in which no histologic diagnosis could be made. Adenomas were present in 34% of the men and 32% of the women. The adenoma prevalence rate increased smoothly with age in men, whereas the rate in women showed a biphasic variation with a peak at 50--59 years followed by a second increase after 70 years of age. The distribution of adenomas within the bowel showed a marked change with age, from a moderate left-sided predominance before 60 years of age to a marked right-sided predominance in patients over 80 years of age, particularly in men. Hyperplastic polyps were present in 27% of the men and 18% of the women. In men, their frequency and distribution within the bowel showed similar changes with age as were seen for the adenomas. In women, no such age-dependency was observed for hyperplastic polyps. Multiplicity of polyps increased with age and was more pronounced in men than in women. Adenomas in women tended to be larger, more atypical, and more villous than in men. A comparison with a similar study from Northern Norway showed no difference in the prevalence of adenomas in spite of a 70% higher incidence rate for colorectal cancer in Oslo.

The prevalence of polyps of the large intestine in Oslo: an autopsy study

The colon and rectum were removed from 445 consecutive autopsies and examined for the presence of polypoid lesions under an illuminating magnifying lens. There were seven clinically undiagnosed carcinomas, 329 adenomas, 174 hyperplastic polyps, 59 mucosal tags, 34 other polypoid lesions, and 54 polyps in which no histologic diagnosis could be made. Adenomas were present in 34% of the men and 32% of the women. The adenoma prevalence rate increased smoothly with age in men, whereas the rate in women showed a biphasic variation with a peak at 50--59 years followed by a second increase after 70 years of age. The distribution of adenomas within the bowel showed a marked change with age, from a moderate left-sided predominance before 60 years of age to a marked right-sided predominance in patients over 80 years of age, particularly in men. Hyperplastic polyps were present in 27% of the men and 18% of the women. In men, their frequency and distribution within the bowel showed similar changes with age as were seen for the adenomas. In women, no such age-dependency was observed for hyperplastic polyps. Multiplicity of polyps increased with age and was more pronounced in men than in women. Adenomas in women tended to be larger, more atypical, and more villous than in men. A comparison with a similar study from Northern Norway showed no difference in the prevalence of adenomas in spite of a 70% higher incidence rate for colorectal cancer in Oslo.

Atherosclerosis and polyps of the colon. Quantification of precursors of coronary heart disease and colon cancer

The prevalence of adenomatous and hyperplastic polyps of the colon and the degree of involvement of the aorta by atherosclerotic lesions were evaluated in 842 autopsies from New Orleans. A positive statistical association between the two variables was found in white males under 75 years of age. In black males a positive correlation between atherosclerotic lesions and adenomatous (but not hyperplastic) polyps was found. The most extensive involvement of the aorta by atherosclerosis was found in patients in whom adenomatous and hyperplastic polyps coincided. The possibilities that dietary factors may account for these findings and its relevance in relation to colon cancer and coronary heart disease are discussed.

Colorectal cancer screening

The efficacy of Hemoccult screening for colorectal carcinoma is analyzed utilizing five criteria which a screening test should fulfil before it is used for mass screening. The Hemoccult screening protocol has serious weaknesses. It is at best 83% sensitive for cancer and much less sensitive for polyps. An asymptomatic person with one or more positive Hemoccult slides only has a 12% chance of having cancer. In addition, patient acceptance of mass Hemoccult screening is questionable. There is currently little information on potential survival benefits, and Hemoccult screening is expensive with one quarter of all costs incurred in the diagnostic evaluation of false positives. There is insufficient evidence to recommend Hemoccult colorectal cancer screening in asymptomatic persons as a cost-effective practice.

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.

Selective screening for colorectal tumors in the Tel-Aviv area: relevance of epidemiology and family history

A selective screening program for the early detection of colorectal tumors was carried out in the Tel-Aviv area. The criteria for inclusion were based, in part, on relevant epidemiologic data which showed that European- and American-born immigrants were at the highest risk for developing this cancer, followed by Israel-born Jews. The Tel-Aviv area, because of its large elderly population of European origin, has a high incidence of colorectal cancer. Families of patients with colon cancer are known to have an increased risk for developing colon tumors. These relatives were actively searched for, and were, along with the control group, examined by Hemoccult testing and flexible sigmoidoscopy. The color tumor (cancer or adenomatous polyps) rate was 6.3% in the group with a family history of colon cancer, as contrasted to 3.8% in a smaller control group without this history. This increased yield, greater than usually found in an unselected population, emphasizes the economic value of selective screening utilizing relevant epidemiologic data and the family history.

Polyps in a low-risk colonic cancer population in Colombia, South America

Colonic polyps were systematically searched for in 508 specimens collected from unselected autopsies in individuals more than 10 years of age from Medellín, Colombia, a low-incidence geographic region for colorectal cancer. Adenomatous polyps have a low prevalence rate in both sexes, comparable to that found in Cali, Colombia and other populations with low risk for cancer. They were found more frequently in the right side of the colon and are rare in the sigmoid colon. They begin to appear in the third decade of life in both sexes. Prevalence rates for single and multiple polyps increase with age in both sexes, males showing higher rates than females at every age group. Adenomatous polyps in this population are usually less than 3 mm in diameter and do not show villous changes or epithelial atypia. Hyperplastic polyps were more frequently observed than adenomatous polyps and rates show a progressive increase with age in both sexes. Multiplicity also increases with age. Most polyps are located in the low rectum and sigmoid followed by the cecum and ascending colon. Usually hyperplastic polyps are smaller than 3 mm in diameter and do not show epithelial atypia. Juvenile polyps were infrequently found in this series because children less than 10 years old were excluded. Diverticular disease was also rare and, when found, was not associated with adenomatous polyps. The association between adenomatous polyps and colonic cancer is discussed based on findings in this report.

Report of a case of precancerous primary duodenal polyp and a review of the related literature

A 62-year-old woman with a precancerous duodenal polyp in the suprapapillary region of the second portion of the duodenum was surgically treated by pancreato-duodenectomy. The postoperative course and follow-up was uneventful. A statistical analysis of primary duodenal tumor cases (excluding tumors of the duodenal papilla) reported in Japan during the period from 1962 to 1977 was also reported.

Distribution of polyps in the large bowel in relation to age. A colonoscopic study

In a colonoscopic study of the anatomical distribution of 600 adenomas, polyps of all sizes in patients up to 55 years old were predominantly located distally. With advancing age of the patients a successively greater proportion of at first small and then also larger polyps was found in the intermediate and proximal parts of the colon. These findings support the assumption that polyps of the gut as a rule originate in the distal part of the large bowel, only later to appear proximally. This concept is important, since it might serve to explain conflicting experience with regard to the site of colorectal tumours.

An analysis of the age distribution of colon cancer in adenomatosis coli

For the purpose of elucidating the genetic and environmental interaction in human carcinogenesis, the age distribution of colon cancer in adenomatosis coli (AC) patients in Japan and England were investigated and compated. According to the multiple mutation theory of carcinogenesis, the rate of tumor production is presented by a natural logarithm of the reciprocal of the survival fraction (the proportion on diagnosed colon cancer by age t either among AC patients or total colon cancer cases), and thus is given by a power function of t. The number of hits necessary for colon cancer development in AC patients was estimated to be 4.2 or 4.4 for males and 3.4 or 3.3 for females in Japanese cases, whereas it was 4.7 or 3.9 and 3.6 or 3.2, respectively, in English cases. The estimates are compatible between countries. On the other hand, from the age specific prevalence curve, number of hits in general population was estimated to be 5.0 for both sexes in Japan, which is approximately one hit less than the values for English general population, at least in males. The present results, when taking into account the geographic and/or chronologic variations in colon cancer frequency, suggest that the etiology of colon cancer in younger patients is primarily determined by a genetic predisposition whilst environmental factors are much more influential for the development of colon cancer in older patients.

Colon cancer: its precursors and companions in Hawaii Japanese

Following migration to Hawaii, the Japanese have acquired the same risk of developing large bowel cancer as that experienced by Caucasians. This tumor is uncommon in Japan. Other conditions are also more common in Hawaii Japanese, e.g., myocardial infarction, severe atherosclerosis, diverticulosis, and polyposis of the colon. Comparative studies in Hawaii and Japan suggest that the basis of these differences is probably related to the consumption of characteristically western foods by Hawaii Japanese.

Adenomatous lesions of the large bowel: an autopsy survey

A comprehensive autopsy survey of the large bowel showed that adenomas were very common lesions occurring in about one-half of the 518 cases studied. The great majority were small adenomatous polyps (tubular adenomas), 86.7% measuring less than 10 mm in diameter. Adenomas with a more complex tubulovillous pattern were larger with a mean diameter of 19.0 mm. There was no apparent incresae in mean size of adenomas with age. Nineteen clinically unsuspected cancers were discovered. Fourteen (8 in situ and 6 invasive) cancers had areas of residual benign adenoma. Five invasive cancers had no residual benign component. No in situ carcinomas or small (less than 10 mm) invasive cancers not containing residual adenoma were found. The results suggest that, although adenomas of the large bowel are very common, the vast majority are simple adenomatous polyps which do not undergo progressive growth and malignant change. Conversely, it appears that cancers may arise from benign adenomas which have the characteristics of large size and a more complex villous architecture.

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.

[Results of rectoscopical investigations in unselected patients: contribution to the problems of prophylactical investigations (author's transl)]

A report and analysis is given about the results of totally 1665 rectoscopical investigations, which were done in unselected patients suffering from common internal diseases. In 7 cases (that means 0.4% of the whole collective) a carcinoma could be detected. An evidently great number of 304 patients were carriers of polyps (that means 17.6% of the whole collective), of whom 77% were male and 23% were female carriers of polyps. The differentiation of the polyps moreover was done according to the histological criteria: There were 126 prospectively precancerous polyps (that means 7.4% of the whole collective of 1665 patients). These results are compared with data in the literature. The number of prospectively important findings is found higher than commonly is expected. The security of the diagnostic significance of the rectoscopical investigations cannot be obtained by other methods of prophylactical investigations. Therefore this method should be practiced in internal, but among all in clinical conditions in first stage. Only more consequent medical procedures in future are able to help to gain more successful results in treating colorectal cancer.

Colon and anorectal neoplasms in a tropical African population

At the University College Hospital, Ibadan, Nigeria, over a 30-month period (January 1975 to June 1977) more than 29 cases were fully studied. Nine patients presented with acute large bowel obstruction. In five cases, colonic neoplasms were palpated abdominally before surgery, and four of the patients were initially being treated for "hemorrhoids". All the patients presented at late stages. There was neither socio-economic nor sexual bias in this affliction. Sixty-nine percent of all the tumors occurred in the anorectal area well within the reach of the index finger, and 27.5% occurred in the right colon. Differential diagnosis included ameboma, rectal schistosomiasis, rectal tubercolosis, anal fistula and adult chronic intermittent intussusception. The treatment administered depended on the nature, location and stage of the disease. There was a case of metastatic squamous cell carcinoma of the hepatic flexure causing obstruction. The metastasis was from carcinoma of the cervix which had been treated with cesium insertions about three years previously. It is now known that colon and anorectal neoplasms, once regarded as rare among Africans living in tropical Africa, is not that rare. With the Africans boycotting native "doctors" in favor of medical institutions, many of the diseases once thought to be rare in Africans will unfortunately become less rare.

Diminutive colonic polyps--clinical significance and management

Of 300 diminutive polyps (up to 5 mm) found at colonoscopy, 114 were neoplastic (37 per cent) and thus possible precursors of carcinoma. This suggests that all colonic polyps, regardless of size, should if possible be extirpated or coagulated. As polyps of this small size often escape detection roentgenologically, especially by conventional technique, colonoscopy should be extended to involve the entire colon. This is because diminutive polyps, especially of neoplastic type, are common also in the proximal part of the colon.

Incidence of large bowel cancer in Côte-d'Or (Burgundy)

The present study is based on the registry of digestive cancers set up for the French department of Côte-d'Or (455,727 residents). Large bowel cancer represents half of the gastrointestinal tract cancers recorded in the course of 2 years (1976-1977). The crude annual incidence rate was 52.2 per 100,000 for males, 41.7 per 100,000 for females. The age-standardized incidence rate for cancer of the rectum is one of the highest reported. The incidence rates for cancer of the colon are in the intermediate range. Half of the large bowel cancers were rectal cancers, nearly always adenocarcinoma. Coexisting benign polyps were seen in 21% of the cases at the time of diagnosis of carcinoma and were more common in males than in females. 54% of cancers of the colon and 62% of cancers of the rectum underwent curative surgery.

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.

[Problem posed by the prevention and detection of colorectal cancers]

The incidence of colonic and rectal carcinoma is in constant progression. The detection and destruction of polyps is the only effective means of reducing the number of adenocarcinomas. The technical means of detection are well known and fully proved: rectosigmoidoscopy, thin layer double contrast enema, colonoscopy. The true problem is that of the cost of this prevention. It is important to define high risk groups in which these tests should be carried out as a routine. Furthermore it is necessary to know whether blood tests or examination of the stools may be considered as a means of detection of polyp or at least certain types of potentially malignant polyp. without suggesting a considerable increase in the number of medical investigations, one may hope for better use of sigmoidoscopy and double contrast barium enema. These two examinations represent undoubtedly the essential factor in the diagnosis of colonic and rectal tumours.

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

Based on a study of the prevalence of intestinal polyps in New Orleans and on international comparisons, the following conclusions are reached. 1) There is a close parallelism in the epidemiology of colon cancer and adenomatous polyps. Both conditions are statistically associated with respect to geography, anatomic localization, socioeconomic class, migration experience and time trends. 2) The strength of the association favors the notion of a direct, positive correlation between multiplicity, size and atypia of polyps, and cancer risk, equivalent to "dose-effect". 3) The epidemiologic findings are coherent with other biologic facts derived from clinical, morphological and experimental studies. 4) Adenomatous polyps are a good epidemiologic indicator of colon cancer risk and their presence should be helpful in advancing from studies of the epidemiology of colon cancer to the epidemiology of precursor lesions.