Small colonic adenomas with adenocarcinoma. A retrospective analysis

ACR Colon Cancer Committee white paper: status of CT colonography 2009

PURPOSE

To review the current status and rationale of the updated ACR practice guidelines for CT colonography (CTC).

METHODS

Clinical validation trials in both the United States and Europe are reviewed. Key technical aspects of the CTC examination are emphasized, including low-dose protocols, proper insufflation, and bowel preparation. Important issues of implementation are discussed, including training and certification, definition of the target lesion, reporting of colonic and extracolonic findings, quality metrics, reimbursement, and cost-effectiveness.

RESULTS

Successful validation trials in screening cohorts both in the United States with ACRIN and in Germany demonstrated sensitivity > or = 90% for patients with polyps >10 mm. Proper technique is critical, including low-dose techniques in screening cohorts, with an upper limit of the CT dose index by volume of 12.5 mGy per examination. Training new readers includes the requirement of interactive workstation training with 2-D and 3-D image display techniques. The target lesion is defined as a polyp > or = 6 mm, consistent with the American Cancer Society joint guidelines. Five quality metrics have been defined for CTC, with pilot data entered. Although the CMS national noncoverage decision in May 2009 was a disappointment, multiple third-party payers are reimbursing for screening CTC. Cost-effective modeling has shown CTC to be a dominant strategy, including in a Medicare cohort.

CONCLUSION

Supported by third-party payer reimbursement for screening, CTC will continue to further transition into community practice and can provide an important adjunctive examination for colorectal screening.

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.

Prevalence of clinically important histology in small adenomas

BACKGROUND & AIMS

The prevalence of advanced histology in small polyps has become a crucial issue in optimizing colorectal cancer screening strategies, especially in view of the advent of computed tomography colonography. We evaluated the prevalence of advanced histology in small and diminutive adenomas to clarify their clinical importance in terms of malignant potential.

METHODS

Data were reviewed retrospectively from 3291 colonoscopies performed on asymptomatic patients found to have an adenoma on screening with flexible sigmoidoscopy a few weeks before the colonoscopy or who had a family history of colorectal cancer. All polyps were excised endoscopically and sent for pathology testing. Specimens with advanced histology were confirmed by a second reading.

RESULTS

Of the 3291 colonoscopies performed, 1235 colonoscopies yielded a total of 1933 small or diminutive adenomatous polyps. Advanced histology including carcinoma was found in 10.1% of small (5-10 mm) adenomas and in 1.7% of diminutive adenomas (< or = 4 mm). Carcinoma was found in .9% of small adenomas, and 0% of diminutive adenomas. Of the 107 patients found to have polyps 2-10 mm with advanced histology, 100 (93%) were referred for colonoscopy because of an adenoma found on a recent screening with flexible sigmoidoscopy. Seven patients underwent colonoscopy for a positive family history of colon cancer; all 7 had a single affected first-degree relative older than age 50.

CONCLUSIONS

Adenomas 5-10 mm in size harbor pathologically significant histology, and the need for removal of these lesions must be addressed to optimize colorectal cancer prevention.

The yield of colonoscopy in average-risk patients with non-specific colonic symptoms

OBJECTIVES

The need for full colonoscopies in average-risk patients with non-specific colonic symptoms is controversial. We aimed to evaluate: (1) the yield of full colonoscopy; (2) the prevalence of proximal neoplasia in these patients; (3) the yield if any of doing full colonoscopies to diagnose proximal lesions in patients in whom the distal colon was clear; (4) the significance of this yield with respect to age.

DESIGN

This is a retrospective analysis to assess the value of open access colonoscopy.

PATIENTS AND METHODS

All patients who underwent a colonoscopy in our Endoscopy Unit during January 1996 to December 1999 were assessed (n = 3357).

RESULTS

We analysed 945 patients with average risk and non-specific colonic symptoms (significant risk factors excluded). The overall yield of adenomas was 5.8%. The yield of distal adenomas in patients > or= 50 years of age was 8.2% (37 out of 450) versus 0.2% in the 50 years group (one out of 495; = 0.0001). The proximal adenoma yield in > or= 50 year olds was 3.8% (17 out of 495) versus 0.2% in < 50 year olds (one out of 495) (P = 0.0001).

CONCLUSIONS

In a cohort of average-risk patients with non-specific colonic symptoms attending an "open access" colonoscopy clinic, the yield for proximal adenomas is small in the < 50 years group. In patients aged < 50 years, distal colonic examination is all that is required, whereas a full colonoscopy may be justified in patients > or = 50 years old.

Diminutive polyps of large bowel should be an early target for endoscopic treatment

BACKGROUND AND AIMS

Aim of the present study is to ascertain the importance of diminutive colorectal polyps and define the need for removal according to their characteristics and malignant potential.

PATIENTS AND METHODS

A total of 4,723 patients who underwent colonoscopy were evaluated and 624 patients with 826 polyps were recorded. There were 352 patients with 443 diminutive polyps, studied according to their distribution. Of these, 371 were removed, histologically examined and correlated to patient characteristics and occurrence of synchronous neoplasms.

RESULTS

Of the right colon polyps, 81/115 were diminutive, versus 362/711 of the left colon (p<0.0001). Adenomas were more common in patients over 50 years of age, (p<0.0001). In all colonic segments, diminutive adenomas prevailed over hyperplastic polyps, whereas the proportion of diminutive adenomas predominated in the right colon (p=0.0015). Adenomas were classified as tubular 39%, tubulovillous 55.7% and villous 5.3%. The degree of dysplasia was mild in 45.5%, moderate in 51% and severe in 3.5%. The prevalence of synchronous neoplasms was 37.4%. They were more frequently found in males over 50 years of age and in patients with diminutive adenomas compared to those with diminutive hyperplastic polyps (p=0.0078).

CONCLUSIONS

The majority of right colon polyps are diminutive. The proportion of diminutive adenomas is higher in patients over 50 years and in the right vs left colon. Diminutive polyps should be removed taking into account the high prevalence of adenomas with a villous component and their significant degree of dysplasia.

Significance of small distal adenoma for detection of proximal neoplasms in the colorectum

BACKGROUND

The significance of the small distal tubular adenoma detected by sigmoidoscopy as a predictor of proximal neoplasm remains controversial. The aim of this study was to examine the prevalence of proximal neoplasms in patients with and without distal neoplasms.

METHODS

This is a retrospective study of 3131 asymptomatic middle-aged men who underwent total colonoscopy. For 812 men with colorectal neoplasms characteristics of the identified neoplasms were determined.

RESULTS

The prevalence of proximal neoplasms in patients with small distal tubular adenoma was 20% (92 of 461), whereas the prevalence of proximal neoplasms in patients without distal neoplasms was 11.5% (301 of 2620). The prevalence of advanced proximal neoplasms in patients with small distal tubular adenoma and without distal neoplasm was 1.3% and 0.8%, respectively. In the 29 patients with advanced proximal neoplasms, only 6 (21%) had a small distal tubular adenoma.

CONCLUSIONS

The presence of small distal tubular adenomas may provide a clue to the presence of small proximal tubular adenomas. However, the majority of advanced proximal neoplasms (79%) do not have a synchronous small distal tubular adenoma. (Gastrointest Endosc 2000;52:358-61).

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

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

Is colonoscopy needed for the nonadvanced adenoma found on sigmoidoscopy? The Polyp Prevention Trial

BACKGROUND & AIMS

The need for colonoscopy when small tubular adenomas with low-grade dysplasia are found on sigmoidoscopy is uncertain. The aim of this study was to examine the prevalence and characteristics of proximal adenomas in patients with distal adenomas.

METHODS

We studied 981 subjects with distal adenomas found on the index colonoscopy before randomization in the Polyp Prevention Trial.

RESULTS

Four hundred sixty patients (46.9%) had >/=1 distal adenoma that was pathologically advanced (villous component, high-grade dysplasia, or >/=1 cm); 21.5% (211 of 981) had any proximal adenoma; and 4.3% (42 of 981) (95% confidence interval [CI], 3.0-5.5) had an advanced proximal adenoma. A greater percentage of patients with an advanced distal adenoma (5.9%) (95% CI, 3.7-8.0) had an advanced proximal adenoma compared with those with a nonadvanced distal adenoma (2.9%) (95% CI, 1.4-4.3) (OR, 2.1; 95% CI, 1.1-4.3; P = 0.03). Not performing a colonoscopy in patients with a nonadvanced distal adenoma would have missed 36% (15 of 42) of the advanced proximal adenomas.

CONCLUSIONS

Patients with an advanced distal adenoma are twice as likely to have an advanced proximal adenoma as patients with a nonadvanced distal adenoma. However, eschewing a colonoscopy in patients with a nonadvanced distal adenoma would result in not detecting a sizeable percentage of the prevalent advanced proximal adenomas. These data support performance of a colonoscopy in patients with a nonadvanced distal adenoma. Confirmation of these results in asymptomatic subjects undergoing screening sigmoidoscopy is advisable.

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.

Small rectosigmoid polyps as markers of proximal neoplasms

PURPOSE

The aim of this study was to determine the spatial distribution and histotype of small colorectal polyps and to determine the validity of distal-small colorectal polyps as markers of proximal neoplasms.

METHODS

In 366 patients who underwent total colonoscopy and removal of all polyps, the presence and features of polyps were recorded. The relationship between proximal neoplasms and distal polyps was investigated in 216 of 366 subjects who had no personal or familial history of colorectal neoplasia.

RESULTS

Of 366 patients, 96 were free from polyps. A total of 733 small colorectal neoplasms was removed from the remainder: 79.9 percent neoplastic and 20.1 percent hyperplastic, inflammatory, or hamartomatous. High-grade dysplasia was noted in 2.7 percent of the neoplastic polyps. One adenoma containing invasive carcinoma was observed. In the subset of 216 patients, proximal neoplasms were found in 11.4 percent of those with no distal polyps, 33.8 percent of those with distal-small colorectal polyps only (P < 0.01), and 58.8 percent of those with at least one polyp > 5 mm in diameter (P = 0.001). The proximal neoplasm percentage was the same in patients with at least one adenomatous-small polyp and those with only hyperplastic-small polyps.

CONCLUSIONS

A distal-small colorectal polyp, whether adenomatous or hyperplastic, may be a proximal neoplasm marker. Total colonoscopy is thus justified in all patients with distal polyps, regardless of their size and histotype.

Cold snare excision of small colorectal polyps

This study describes a new technique for excision of small colorectal polyps in a series of 210 consecutive patients, who had total colonoscopy, and in whom any clotting problems had been excluded. A total of 288 small polyps of 5 mm or less in diameter were transected by mechanical strangulation with a polypectomy snare, but without applying any electrical energy. All polyps were recovered whole and sent for histologic examination. No case of perforation, serious bleeding, or mortality was recorded, nor was there any need for blood transfusion because of sudden or delayed bleeding. Of the small polyps, 56% were adenomas, 43% hyperplastic, and 1% were other types. No invasive cancer was found, but in seven small adenomas severe dysplasia was observed. No correlation between the macroscopic appearance of small polyps at endoscopy and their nature at histology was found. Our data confirm that all visible polypoid lesions of the colon should be removed, and that cold snare excision of small polyps is a safe and effective alternative method of treatment in patients without clotting problems.

An appraisal of small and diminutive colonic polyps

A retrospective review of all colonoscopic polypectomies performed in a busy surgical endoscopy unit over a 6-month period was undertaken. All patients were included who presented with colonic polyps measuring less than 1 cm in diameter for which sufficient specimens were available for histopathologic examination. In all, 262 were polyps removed from 206 patients; of these, 158 (60%) were neoplastic. There was a statistically significant predilection for polyps in the right colon to be neoplastic. Worrisome histologic patterns (severe dysplasia, carcinoma in situ, or invasive carcinoma) were seen in 18 specimens (6.5%). In two patients, polypoid carcinoma could be identified; in one case it involved a lesion measuring 0.2 cm in diameter. Since these lesions exhibit no distinctive gross features, only their endoscopic removal and histologic study can ensure proper diagnosis and treatment.

Primary de novo adenocarcinoma of the colon measuring 8 mm in diameter with lymph node metastases. Report of a case

Colonic adenocarcinomas measuring less than 10 mm are rare. Herein, we report a carcinoma measuring 8 mm in diameter associated with subserosal extension through a "locus minoris resistentiae" and metastases to lymph nodes, an association not previously reported. No residual adenomatous tissue was found, suggesting a de novo carcinoma.

Usefulness of performing colonoscopy one year after endoscopic polypectomy

This retrospective study defines a population with neoplastic colonic polyps who have had colonoscopic polypectomy and, in follow-up within one year, a repeat colonoscopic evaluation. The population was broken down into two groups, one group that had polyps at the second examination and one group that did not. This study determined which factor(s) were significant among this population in distinguishing whether new polyps would be found at one year follow-up. The authors found that among the many variables studied, only polyp multiplicity was significant in predicting polyp recurrence. More than one polyp found at index colonoscopy led to a significant chance of having a new polyp after only one year. Also, it was demonstrated that these "new" polyps were unlikely to have been "missed" polyps from the initial colonoscopy. Because of the shifting location, smaller size, and fewer instances of histologic atypia in these polyps compared with those at index examination, the authors believe that polyps found after one year may be assumed to have arisen de novo. Finally, the authors show that a significant number of polyps occur beyond the reach of the flexible sigmoidoscope (approximately 60 cm). The authors recommend that patients who have polyps undergo a colonoscopic examination. When patients are re-evaluated after having colonoscopic neoplastic polypectomy, they should undergo repeat colonoscopy.