Follow-up study of patients with benign mucosal polyps discovered by proctosigmoidoscopy

Recurrence and malignancy rates in a benign colorectal neoplasm patient cohort: results of a 5-year analysis in a managed care environment

OBJECTIVE

To estimate the apparent recurrence rates of benign neoplasms and the development of malignant colorectal neoplasms over a 5-yr period in a high risk managed care population.

METHODS

Using the CPT and ICD-9 CM codes, a cohort of subjects with benign neoplasms were identified with a colonoscopy in 1992 from a longitudinal claims database (MarketScan). Three groups of subjects (benign neoplasms with polypectomy, benign neoplasms without polypectomy, and no neoplasms) were evaluated. Five-year recurrence rates of benign or new malignant colorectal neoplasms were determined for the baseline benign neoplasms with polypectomy and no neoplasm groups. For the benign neoplasm without polypectomy, only rates for malignancy were evaluated.

RESULTS

Of 16,293 subjects at baseline, 39.50% were diagnosed with benign and 5.50% with malignant neoplasms. The 5-yr cumulative incidence of benign neoplasms in subjects without an index neoplasm (n = 8,967) was 7.92% compared to the recurrence of 40.93% in subjects with a benign neoplasm and polypectomy (n = 4,046) at baseline (p < 0.001). The 5-yr cumulative incidence rates of malignant colorectal neoplasms in the no neoplasm (n = 8,967) and benign neoplasm groups (n = 6,438) were 1.81% and 2.55%, respectively (p < 0.005). A lower 5-yr malignancy rate was observed in benign neoplasm group with polypectomy (2.17%) compared to the benign neoplasm group without polypectomy (3.18%) (p < 0.05).

CONCLUSION

The high recurrence rate of benign colorectal neoplasms and a higher incidence of colorectal cancer in subjects at high risk (history of benign colorectal neoplasm) highlight a healthcare opportunity for surveillance and/or interventions to reduce the morbidity associated with colorectal neoplasms.

Zollinger-Ellison syndrome, acromegaly, and colorectal neoplasia

Zollinger-Ellison syndrome (ZES) and acromegaly are two hypersecretory states in which colorectal neoplasia has been described, but the incidence in the former condition may not be increased. We describe four patients with colorectal neoplasia associated with the ZES and review other published cases. Tissue ELISA with Adnab-9 antibody, a putative colorectal cancer risk marker, from a patient with ZES and from seven patients with acromegaly was compared to 13 controls at average risk for colorectal neoplasia. The patient with ZES without detectable colonic neoplasia and seven patients with acromegaly had increased binding of Adnab-9 in the colonic mucosa by ELISA. The difference was significant for the acromegaly patients compared to the controls (p < 0.05). The accumulated 34 instances of colorectal neoplasia in ZES patients suggests that this association may not be rare. Adnab-9 expression, detectable in both ZES and acromegaly, may reflect predisposition to colorectal neoplasia in both hyper-secretory states. Therefore, while a basis for association of colorectal neoplasia and hypergastrinemia exists, the clinical data are not compelling enough to warrant surveillance of patients with ZES. To resolve this problem, more definitive case control studies should be conducted.

Early detection research program at the NCI

The Early Detection Branch, Division of Cancer Prevention and Control, National Cancer Institute, has created a program called The Early Detection Research Network (EDRN). EDRN's mission is to support translational research leading to early detection of cancer. The objectives are to (i) establish a network of institutions with the facilities, resources, personnel and interest to undertake biomarker research in early cancer detection; (ii) advance the understanding of the molecular basis of tumorigenesis in relation to screening, early detection and risk assessment; (iii) identify potential biomarkers that can be used as outcome measures or as intermediate end-points for cancer screening studies and (iv) respond to late-breaking developments in the field of biomarkers in a timely fashion. This program has the singular purpose of studying biologic, molecular and genetic markers relevant to the early detection of prostate, colorectal, lung, head and neck, bladder and breast cancers.

Does colonoscopic polypectomy reduce the incidence of colorectal carcinoma?

The study's objective was to examine whether there is evidence that colonoscopic polypectomy reduces the incidence of colorectal cancer. The records of all patients who underwent colonoscopic polypectomy by a single surgeon between 1974 and 1991 were reviewed. Patients with colorectal cancer diagnosed at the initial colonoscopy, with a history of colorectal cancer, inflammatory bowel disease or familial adenomatous polyposis or with only hyperplastic polyps were excluded. There were 1008 remaining patients, of whom 645 have attended at least one follow-up colonoscopic examination, and these 645 patients from the basis of the study, because the incidence of cancer is known exactly in this group. The mean period of follow up was 4.4 years and the mean number of follow-up colonoscopic examinations was 2.2. There was a total of 2847 person-years of colonoscopic follow up. The expected incidence of cancer, age and sex adjusted, is calculated using Australian epidemiological figures. The observed incidence of cancer was 3 cases (all asymptomatic) per 2847 person-years, which is indistinguishable from the general population's risk of 3.75 cases per 2847 person-years. Analysis of previous publications suggests that patients with adenomas are at an increased risk of developing colorectal cancer of about 2.5 times the general population's risk. If correct, then the observed incidence of 3 cases per 2847 person-years is less than the expected incidence of 9.4 cases per 2847 person-years. This analysis suggests colonoscopic polypectomy does reduce the incidence of colorectal cancer.

Long-term risk of colorectal cancer after excision of rectosigmoid adenomas

BACKGROUND AND METHODS

Surveillance by repeated colonoscopy is currently recommended for patients with colorectal adenomas. We assessed the long-term risk of colorectal cancer after rigid-instrument sigmoidoscopy and polypectomy in 1618 patients with rectosigmoid adenomas (tumor of the rectum or distal sigmoid colon) who did not undergo surveillance. A total of 22,462 person-years of observation were accrued (mean, 14 years per patient).

RESULTS

The incidence of subsequent rectal cancer in these patients was similar to that in the general population (standardized incidence ratio, 1.2; 95 percent confidence interval, 0.7 to 2.1). Most rectal cancers developed in patients whose adenomas had been inadequately removed; the risk was very low after complete removal. The risk of subsequent colon cancer depended on the histologic type, size, and number of adenomas in the rectosigmoid. Among 842 patients with a rectosigmoid adenoma that was tubulovillous, villous, or large (greater than or equal to 1 cm), colon cancer developed in 31 patients. The standardized incidence ratio was 3.6 (95 percent confidence interval, 2.4 to 5.0) overall and 6.6 (95 percent confidence interval, 3.3 to 11.8) if there were multiple rectosigmoid adenomas. Among the remaining 776 patients with only small, tubular adenomas (whether single or multiple), colon cancer developed in only 4 patients. The standardized incidence ratio in this group was 0.5 (95 percent confidence interval, 0.1 to 1.3).

CONCLUSIONS

Follow-up colonoscopic examinations may be warranted in patients with tubulovillous, villous, or large adenomas in the rectosigmoid, particularly if the adenomas are also multiple. In patients with only a single, small tubular adenoma that is only mildly or moderately dysplastic (43 percent of our series), however, surveillance may not be of value because the risk of cancer is so low.

Phenotypic markers for a spectrum of colonic polyps and cancers. The malignancy potential ratio

The purpose of this study was to determine if a panel of monoclonal antibodies could define phenotypic markers that could be used in risk assessment of a spectrum of colonic polyps and colon cancers. Using the ABC immunoperoxidase technique on formalin-fixed sections of surgical specimens, the following results were obtained: 1) Mab B72.3 demonstrated increased reactivity in villous lesions and cancers compared with hyperplastic polyps and tubular adenomas; 2) Mab anti-CAA demonstrated increased reactivity in polyps compared with colon cancers; and 3) using the two antibodies (Mab B72.3 and Mab anti-CAA), a malignancy ratio was obtained that determined malignancy risk for individual polyps. No hyperplastic polyp gave a positive ratio, but about 30 percent of villous lesions were positive. Over 50 percent of villous lesions greater than 2 cm in size had a positive ratio. The malignancy potential ratio may be a valuable marker in assessing risk of malignancy in an individual case.

Role of sigmoidoscopy in screening for colorectal cancer: a critical review

The use of sigmoidoscopy as a screening method for colorectal cancer is controversial. Evidence regarding its efficacy is reviewed critically, with special attention given to potential biases in screening studies. The vast majority of studies are uncontrolled and without follow-up information and thus shed little light on the actual benefits of sigmoidoscopy. Two uncontrolled studies with follow-up and one randomized trial suggest a colorectal cancer mortality reduction because of the use of sigmoidoscopy, but all three studies have major shortcomings. The authors conclude that the currently available data are insufficient to establish a national recommendation for screening with sigmoidoscopy. To establish such a recommendation, a properly conducted randomized trial with colorectal cancer mortality as an outcome is needed.

Prognostic evaluation of planned follow-up in patients with colorectal adenomas. An interim report

Between 1978 and 1986 colorectal adenomas without invasion were removed in 552 patients under 76 years of age. Patients were randomly allocated to different follow-up groups with intervals of colorectal examination varying from 6 to 48 months after the initial polypectomy. A large bowel carcinoma developed in three patients and new adenomas in 87 patients. Based on the morphology of the initial adenomas possible relationships between prognostic factors and the risk of new adenoma formation were assessed using life-table analysis. The advantage of a possible decrease in the risk of developing carcinoma was offset by the disadvantage of eight severe complications occurring in 1818 colonoscopies, one of which proved fatal. The occurrence of one of the three carcinomas was considered a failure of the follow-up programme.

Repeat colonoscopy after endoscopic polypectomy

The records of all patients undergoing endoscopic polypectomy between December 1979 and December 1982 were reviewed. One hundred seventy-two patients underwent colonoscopic polypectomy in the absence of carcinoma or inflammatory bowel disease. Of these, the polyp could not be retrieved in 4, and 19 were lost to follow-up. One hundred forty-nine patients underwent subsequent endoscopy from one to four years after the initial polypectomy. Seventy-five (50.3 percent) of the patients developed new polyps. Although 61 of the 75 patients with new polyps were identified in the first two years, new polyps were noted throughout all four years. The presence of multiple polyps on the initial examination was statistically significant in predicting new polyps. The age and sex of the patients, size of the polyps, and the presence of atypia did not identify patients at higher risk for new polyps. The data indicate that new polyps are more likely to develop in patients who had a previous polyp. It would appear that annual examinations should be performed until two successive examinations are negative. Following a second negative examination, reexamination at two- or three-year intervals, unless symptomatic, would appear to be adequate.

Metachronous colorectal cancer. Time interval to presentation of a metachronous cancer

A retrospective review of 1888 colorectal cancer patients demonstrated 37 metachronous cancers in 30 patients for a metachronous cancer rate of 1.6 percent. Evaluation of the index cancers consisted of the traditional single-contrast barium enema and proctoscopic evaluation. Forty percent of the metachronous cancers appeared within two years of the index cancer. If the minimum length of the polyp-cancer sequence is three to five years, then this represents a failure of a traditional preoperative evaluation. A more sensitive evaluation potentially could decrease the metachronous cancer rate. Colonoscopy, which has been found to be more accurate in detecting synchronous neoplasms, should be included in the evaluation of all patients with colorectal cancers.

Colorectal polyps and the risk of subsequent carcinoma

Of 323 patients with colorectal polyps that either were larger than 1 cm in diameter or were 1 cm or smaller but had been subjected to biopsy or excision, 20 (6%) had subsequent development of a colorectal carcinoma, an incidence rate of 4.6 per 1,000 person-years of follow-up. These 20 cases of cancer compared with 7.38 cases expected; thus, the risk of colorectal carcinoma in these patients was 2.7 times that in the general population (P less than 0.001). Although risks were greater for certain subgroups of patients, the differences detected were usually modest. We conclude that patients with large colorectal polyps (more than 1 cm in diameter) should be closely followed up after treatment of the initial polyp, regardless of the size, site, or histologic type of the polyp, the age or sex of the patient, or the type of initial treatment (excision or fulguration). Those patients with more than one polyp, especially if more than one segment of the colon is involved, need special attention. Examination of the entire colon is important because the site of development of carcinoma may be distant from the site of the initial polyp.

The significance of synchronous carcinoma and polyps in the colon and rectum

The relationship of colorectal carcinoma with polyps was studied retrospectively in 1202 patients. The incidence of synchronous carcinoma (SC) and metachronous carcinoma (MC), prognosis, and recurrence patterns were studied. Synchronous polyps (SP) were found in 36% of the patients. SC was found in 4.4% of the patients, and MC developed in 3.5% of patients. The incidence of SC and of MC increased with SP, and varied according to number, size, and histologic features of the polyps. The adjusted 5-year survival rate was improved in patients with SP compared with those without SP, both overall (79% versus 64%, respectively) and by Dukes' Stage B (87% versus 73%, respectively) and Dukes' Stage C (56% versus 39%, respectively). The pattern of relapse was the same for the SP and non-SP groups. Subtotal colectomy is recommended for colorectal carcinoma and SP in good-risk patients.

Recurrence rates for colorectal polyps

Of 276 patients who underwent an initial colonoscopic polypectomy for adenomatous polyps over a 45-month period, 118 subsequently had one or more repeat screening colonoscopies. The mean follow-up time was 26 months with an overall polyp recurrence rate of 30%. Analysis of these data retrospectively suggests that the bulk of the recurrences occurred within the first year. Increasing age was found to be a significant risk factor for polyp recurrence. Asymptomatic recurrence of adenomatous polyps detectable by colonoscopy is a common occurrence in postpolypectomy patients. Prospective studies utilizing colonoscopy as a screening tool are needed to establish a rational screening policy for this high-risk group.

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.

The changing distribution of large intestinal cancer

In recent years, several accounts have reported a proximal migration of colorectal cancer. To determine the experience at the Jewish General Hospital in Montreal, 1044 cases of large-bowel cancer that presented between the years 1955 and 1978 were analyzed. The colon was arbitrarily divided into five anatomic regions, and the distribution of cancer in each region for each of eight three-year periods was calculated. An increase in right-sided lesions occurred from 15.6 per cent in the first three-year period to 37.6 per cent in the final three-year period (P less than 0.01). No significant change occurred in transverse and left-colon lesions. An increase in sigmoid carcinomas occurred from 14 per cent to 35 per cent (P less than 0.01). A dramatic decrease in rectal carcinoma from 53 per cent to 2.1 per cent occurred (p less than 0.001). These findings imply that methods for the early detection and screening of large-bowel carcinoma should be directed at the entire colon rather than the distal 25 cm.

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.

Risk of recurrence of colon polyps

At Wood Veterans Administration Center, 268 patients who had a polypectomy have been followed up to 20 years with semiannual proctosigmoidoscopic and barium enema examinations. For the present review of benign polyp disease, patients having coexisting carcinoma, chronic inflammatory disease, and those lost to followup have been excluded; 154 patients followed for a mean of 7 years comprise the study group. Thirty per cent of patients developed recurrent polyps. The risk of recurrence during the first year was 16 times that expected in a population of similar age and sex, but thereafter diminished steadily. After 48 months risk of polyp recurrence was little higher than the incidence expected in a normal population. Neither patient age, presenting symptoms nor the site or size of the initial polyp(s) were of any prognostic value regarding recurrence. Patients presenting with a villous adenoma or with more than 3 polyps had a significantly increased risk of recurrence may persist indefinitely. The overall incidence of colonic carcinoma may have been increased, but the location of subsequent cancer was not related to the site of a previously excised polyp.