Reliability of in situ measurements of colorectal polyps

Mis-sizing of Adenomatous Polyps is Common among Endoscopists and Impacts Colorectal Cancer Screening Recommendations

Background/Aims

To determine the accuracy of identifying ≥6-mm adenomatous polyps during colonoscopy and define its impact on subsequent interval screening.

Methods

We conducted a retrospective study of patients who underwent colonoscopies at Banner University Medical Center, Tucson from 2011 to 2015. All patients with ≥6-mm adenomatous polyps based on their colonoscopy report were included. Adenomatous polyps were excluded if they did not meet the criteria. Discrepancies in the polyp size were determined by calculating the percentage of size variation (SV). Clinical mis-sizing was defined as SV >33%.

Results

The polyps analyzed were predominantly <10 mm in size. Approximately 13% of the examined polyps met the inclusion criteria, and 40.7% of the adenomas were ≥10 mm. A total of 189 ≥6-mm adenomatous polyps were collected from 10 different gastroenterologists and a colorectal surgeon. Adenomatous polyps were clinically mis-sized in 56.6% of cases and overestimated in 71.4%. Among the adenomas reviewed, 22% of mis-sized polyps and 11% of non-mis-sized polyps resulted in an inappropriate surveillance interval.

Conclusions

We found that more than half of ≥6-mm adenomatous polyps are mis-sized and that there is a tendency to overestimate adenoma size among endoscopists. This frequently leads to inappropriate intervals of surveillance colonoscopy.

Screening for Colorectal Cancer Using a Multitarget Stool DNA Test: Modeling the Effect of the Intertest Interval on Clinical Effectiveness

BACKGROUND

A multitarget stool DNA (mt-sDNA) test was recently approved for colorectal cancer (CRC) screening for men and women, aged ≥ 50 years, at average risk of CRC. The guidelines currently recommend a 3-year interval for mt-sDNA testing in the absence of empirical data. We used clinical effectiveness modeling to project decreases in CRC incidence and related mortality associated with mt-sDNA screening to help inform interval setting.

MATERIALS AND METHODS

The Archimedes model (Archimedes Inc., San Francisco, CA) was used to conduct a 5-arm, virtual, clinical screening study of a population of 200,000 virtual individuals to compare the clinical effectiveness of mt-sDNA screening at 1-, 3-, and 5-year intervals compared with colonoscopy at 10-year intervals and no screening for a 30-year period. The study endpoints were the decrease in CRC incidence and related mortality of each strategy versus no screening. Cost-effectiveness ratios (US dollars per quality-adjusted life year [QALY]) of mt-sDNA intervals were calculated versus no screening.

RESULTS

Compared with 10-year colonoscopy, annual mt-sDNA testing produced similar reductions in CRC incidence (65% vs. 63%) and related mortality (73% vs. 72%). mt-sDNA testing at 3-year intervals reduced the CRC incidence by 57% and CRC mortality by 67%, and mt-sDNA testing at 5-year intervals reduced the CRC incidence by 52% and CRC mortality by 62%. At an average price of $600 per test, the annual, 3-year, and 5-year mt-sDNA screening costs would be $20,178, $11,313, and $7388 per QALY, respectively, compared with no screening.

CONCLUSION

These data suggest that screening every 3 years using a multitarget mt-sDNA test provides reasonable performance at acceptable cost.

Variable interpretation of polyp size by using open forceps by experienced colonoscopists

BACKGROUND

Endoscopic measurement of colorectal polyps by using open forceps is commonly used in clinical trials but is subject to several sources of error.

OBJECTIVE

Assess error rates in polyp size determination with open forceps at the step of measurement after the forceps are aligned on the polyp.

DESIGN

This was a prospective assessment of 49 gastroenterologists who received training on 10 photographs of polyps with aligned forceps and then measured 10 additional test polyps from photographs. One of the test photographs was excluded because of incorrect forceps alignment.

SETTING

Data analyzed at an academic medical center.

INTERVENTION

Photographs displayed in a webinar.

MAIN OUTCOME MEASUREMENTS

Description of rates of accurate measurements, including the fraction correct within 50% and 25% margins of error.

RESULTS

A total of 37% of all measurements were correct to the exact millimeter, 34% were larger, and 29% smaller compared with the reference standard. A total of 47 of 49 doctors measured all 9 polyps within 50% of the reference standard, and 21 measured all 9 correctly within a 25% error margin.

LIMITATIONS

Other potential sources of error in open forceps measurement were not evaluated.

CONCLUSION

Open forceps polyp size determination is subject to error at the step of using the fully aligned forceps as a scale for measurement. A margin of error of 50% up or down is needed to prevent this step in size determination from causing errors in polyp matching in clinical trials comparing diagnosis-only imaging to colonoscopy.

Endoscopic mis-sizing of polyps changes colorectal cancer surveillance recommendations

BACKGROUND

Adenomatous polyps greater than 1 cm are defined as advanced adenomas. Inaccurate size estimation can lead to inappropriate surveillance recommendations of colorectal adenomas.

OBJECTIVE

The aim of this study was to determine the impact of endoscopic polyp mis-sizing on colorectal cancer surveillance recommendations.

DESIGN

This is a prospective study.

SETTING

This study was conducted in a gastroenterology practice at a US academic medical center.

PATIENTS

Patients undergoing colorectal cancer screening and surveillance colonoscopies from 2010 to 2011 were included.

MAIN OUTCOME MEASUREMENTS

Endoscopic size estimates of polyps 10 to 25 mm were compared with postfixation histopathologic polyp measurements for 15 different gastroenterologists. Only adenomatous polyps removed in entirety by snare polypectomy were included in the analysis. Size variation was defined as (endoscopic estimate - histopathologic size)/(histopathologic size). Clinical mis-sizing was defined as a size variation of >33%. The mean size variation, the percentage of clinical mis-sizing, and the percentage of inappropriate surveillance recommendation due to size variation >33% were reported per endoscopist.

RESULTS

: Included for analysis were 4990 procedures from 15 gastroenterologists. A total of 230 polyps from 200 patients met inclusion criteria. The average age was 62.6 years (SD 10.1), and 52% were men. The mean size variation between the endoscopic polyp size estimation and the histopathologic polyp was 73.6% (range of mean size variation, 13%-127%). 62.6% (range, 0%-91%) of included polyps had clinical mis-sizing. Of included polypectomies, 35.2% (range, 0%-67%) resulted in an inappropriate surveillance recommendation due to clinical mis-sizing even after considering histology and synchronous polyps.

LIMITATIONS

This was a single-center study.

CONCLUSIONS

There is marked variation in endoscopists' ability to accurately size adenomatous polyps. Some endoscopists rarely mis-size adenomas, and their surveillance recommendations are appropriate in regard to sizing. However, other endoscopists inaccurately size adenomas, and this leads to inappropriate surveillance of colorectal polyps. In this study, approximately 1 of 3 included polypectomies yielded inappropriate surveillance recommendations because of clinical mis-sizing.

Prospective blinded comparison of polyp size on computed tomography colonography and endoscopic colonoscopy

BACKGROUND & AIMS

The size of polyps found on computed tomography colonography (CTC) has been suggested as the major determinant of patient management. We compared polyp size as seen on CTC with endoscopic visualization, in vivo probe measurement, and ex vivo size before and after fixation.

METHODS

Polyps measured on CTC sent for endoscopic removal were evaluated for polyp size in a blinded fashion by endoscopic estimation, in vivo probe measurement, and after removal.

RESULTS

Fifty-six polyps were included in the study. There was no significant difference between CTC polyp size, real-time colonoscopy size estimation, or probe measurement. The size of polyp measured immediately ex vivo and after pathology fixation was significantly smaller. Management would be altered in 6 of 56 polyps (10.7%) on the basis of differences between size of the polyp on endoscopy and CTC.

CONCLUSIONS

(1) CTC polyp size measurement is not significantly different from colonoscopy in vivo visual estimation and linear probe measurement. (2) Differences in size of polyps as measured on CTC and endoscopy will affect patient management in 10% of cases.

Endoscopic imaging and size estimation of colorectal adenomas in the multiple intestinal neoplasia mouse

BACKGROUND

The scientific potential of animal models of carcinogenesis has not been fully realized because of our limited ability to monitor tumor growth in vivo.

OBJECTIVE

To develop an endoscopy-based protocol for the accurate estimation of adenoma size in vivo from images obtained during colonoscopy.

DESIGN

To compare estimates of lesion size acquired during endoscopy with those obtained from magnetic resonance imaging (MRI) and at necropsy.

SETTING

A small-animal imaging facility.

SUBJECTS

Adenomatous polyposis coli multiple intestinal metaplasia Fox Chase Cancer Center mice that develop multiple colorectal adenomas.

METHODS

The mice received colonoscopic examination by using a rigid endoscope, and high-resolution images of colon adenomas were captured by using a charge-coupled-device camera. Lesion size was estimated by comparing the dimensions of the adenoma relative to a reference rod by using a novel geometric construction. The resulting areas were compared with estimates from MRIs and validated at necropsy.

MAIN OUTCOME MEASUREMENTS

Cross-sectional area of colon adenomas.

RESULTS

The cross-sectional area of 20 adenomas was measured in vivo during colonoscopy and compared with the size as measured at necropsy, which yielded a Pearson correlation coefficient of 0.94 (P = 6.52 x 10(-9)). Assessment of interoperator variability, when using measurements from 11 adenomas, yielded a Pearson correlation coefficient of 0.85 (P = 4.35 x 10(-3)) and demonstrated excellent reproducibility.

LIMITATIONS

Only the distal colon could be viewed, and endoscopic measurements were 2-dimensional.

CONCLUSIONS

An endoscopic method for the reliable measurement of colorectal adenomas in vivo was established. The application of this technique to mouse models of colon carcinogenesis will provide unique insight into the dynamics of adenoma growth.

Dietary Habits and Growth and Recurrence of Colorectal Adenomas: Results From a Three-Year Endoscopic Follow-Up Study

Diet has been associated with sporadic colorectal cancer (CRC) risk. The relationship to the growth rate of adenomas is largely unknown. Previous analyses of our cohort of polyp cases have shown 1) indicators of a healthy diet were inversely associated with adenoma occurrence, 2) diet was related to the fecal profile, 3) obesity was positively associated with adenoma growth, 4) familial predisposition of CRC was positively associated with adenoma growth, and 5) intervention with calcium and antioxidants was not associated with adenoma growth. The present aim was to study the effects of diet on growth and recurrence of adenomas. Data were collected from a 3-yr polyp growth and intervention study. Polyps larger than 9 mm were removed, whereas the remainder and newly discovered polyps smaller than 10 mm were left in situ for 3 yr. Diet was assessed by a 5-day dietary record by weighing (DR) and food-frequency questionnaire (FFQ). Weak inverse associations were found only between adenoma growth and fruits and berries (adjusted odds ratio, aOR = 0.3; 95% CI = 0.1-0.9) and carbohydrates (aOR = 0.1; 95% CI = 0.1-0.6; both only DR data) and between adenoma recurrence and vegetables (crude odds ratio, cOR = 0.4; 95% CI = 0.1-0.9; only FFQ data). Taken together, the present and previous findings from this cohort may indicate an early role for dietary factors in CRC development.

Genetic and protein markers related to in situ growth and multiplicity in small sporadic colorectal adenomas

BACKGROUND

Some early genetic events in the development of colorectal adenomas are known, but their relationship to in vivo growth characteristics is uncertain. This study compared in situ size changes and other clinicopathological variables with selected genetic and protein markers.

METHODS

56 adenomas (< or = 10 mm) from 39 patients were analysed for APC, CTNNB1 and K-ras mutations, allelic imbalance on 1p and 18q, microsatellite instability and immunohistochemical expression of HLA-DR, BAX, BCL-2 and Ki-67. For 42 of the adenomas, in situ growth was measured over 3 years. The total number of polyps in each patient was recorded.

RESULTS

K-ras was mutated in 8/56 adenomas. None of the regressing adenomas revealed such mutations, compared to 20% in those that maintained or increased their size. Multivariate linear regression analysis showed that tumour growth was higher in females compared to males, and was even higher in the presence of a K-ras mutation. APC mutations were found in 37/56 adenomas. CTNNB1 mutations were found in 2/19 adenomas without APC mutation. Deletions of 1p were found in 12/56 adenomas and, seemingly, most frequent in patients with few tumours. The most frequently expressed protein was BAX (33/41), but neither this nor the other proteins showed associations with an in situ growth pattern.

CONCLUSION

The multivariate linear regression model showed that patient gender and the presence of K-ras mutation had significant effects on tumour growth. The lack of the proliferative stimulus resulting from a K-ras mutation may contribute to the process of adenoma regression.

Does high body fatness increase the risk of presence and growth of colorectal adenomas followed up in situ for 3 years?

OBJECTIVE

Obesity is an increasing problem for industrialized nations. The incidence of colorectal cancer has also risen during the last decades. However, information is scarce about the association between the colorectal cancer precursors, adenomatous polyps, and body composition. Our aim was to find out if body fatness is related to the presence of polyps and of growth of adenomas of < or =9 mm observed in situ over 3 yr.

METHODS

Twenty-eight outpatients with colorectal polyps and 50-75 yr of age were compared with 34 sex- and age-matched (+/-5 yr) polyp-free healthy controls. The polyp patients were randomly selected from a double blind 3-yr placebo-controlled endoscopic follow-up and intervention study against growth and recurrence of polyps among 116 polyp-bearing outpatients. Triceps skinfold thickness (TSF) was measured by a Harpenden caliper and total body fat percentage (BF%) by Futrex 5000. Dietary intake was calculated in a 5-day dietary record by weighing. Demograpic data, including smoking and alcohol habits, were registered by an interview and self-administrated questionnaires. Weight and height were measured.

RESULTS

TSF and BF% ranked 66% of the individuals into the same quartiles, and 34% were ranked into the adjacent quartiles. The coefficient of correlation between TSF and BF% was highly significant (r = 0.90, p < 0.01, n = 62). TSF, BF%, and body mass index (kg/m2) did not differ between polyp patients and controls in either crude or adjusted analyses. Adenoma growth was, however, highly associated with increasing levels of TSF (p = 0.004), BF% (p = 0.02), and body mass index (p = 0.006).

CONCLUSIONS

Our data suggest that high body fatness is a promoter of adenoma growth. Similar results were obtained with the caliper and Futrex 5000, which lends credibility to this study. For repeated documentation, a larger study population should be investigated. To our knowledge, this is the first case-control study to investigate the relationship between body composition and growth of adenoma by follow-up in situ over 3 yr.

The pathologic measurement of polyp size is preferable to the endoscopic estimate

BACKGROUND

There is no standardized technique to measure polyp size. Estimation of polyp size at endoscopy is difficult. Polyp size measurement by pathologists would seem to be an accurate alternative, but tissue fixation may alter polyp size. To evaluate methods of determining polyp size, we compared endoscopists' estimates and pathologists' measurements with measurements made by an independent examiner.

METHODS

Polyps were measured by an independent investigator before and after formalin fixation. The investigator's measurement before fixation (the "gold standard") was compared with the endoscopists' estimates and the pathologists' measurements.

RESULTS

Ten endoscopists removed 61 polyps with a snare in 33 patients: 82% were adenomatous and 72% were pedunculated. Mean size was 0.85 +/- 0.6 cm (SD) (range: 0.3 to 3.6 cm, 26% > or = 1 cm). Polyps remained in formalin for a mean of 239 minutes (46 to 1164 minutes). Polyps neither consistently shrank nor enlarged in formalin (maximum change +/- 0.2 cm, r = 0.99 [p < 0.001]). Interobserver agreement between pathologists' and the investigator's post-formalin measurements showed that 55 of 57 polyps (97%) were within +/- 0.3 cm. Endoscopists inaccurately estimated 11 of 56 polyps (20%) (> 0.3 cm difference from the independent examiner). Polyp size was underestimated in three instances (range 0.5 to 0.9 cm) and overestimated in eight (range 0.4 to 0.8 cm). In 5 of 11 instances (46%), this inaccuracy altered polyp size classification across the 1 cm threshold. Results were not dependent on endoscopist, histology, or polyp location.

CONCLUSIONS

(1) Polyp size is not significantly affected by formalin fixation; 2) Endoscopists' estimates of polyp size are often unreliable; and, when possible, (3) Pathologists' measurements of polyp size should be used in clinical trials and in clinical practice.

Is in vivo measurement of size of polyps during colonoscopy accurate?

BACKGROUND

Accurate measurement of polyp size during colonoscopy is important because of the direct correlation of size with colon cancer. Major studies of colorectal neoplasms have measured polyp size differently. It is also well documented that endoscopists underestimate polyp size frequently. The goal of this prospective study was to determine which one of the five methods of estimating polyp size during colonoscopy is most accurate.

METHODS

One hundred colon polyps were measured by means of visual estimation, open biopsy forceps methods, linear probe, a ruler immediately after excision, and after fixation in formalin. The size of the polyps measured outside the body immediately after excision was considered the "gold standard" against which all measurements were compared.

RESULTS

Forty-seven polyps were 5 mm or less in diameter, 33 polyps were 5.01 mm to 10 mm, and 20 polyps were more than 10 mm in size. For all polyps the mean difference versus the actual size of the polyps was 3.4% for linear probe, 6.4% for visual estimation, and 12.3% for the forceps.

CONCLUSION

Measurement of polyp size by linear probe agreed best with the actual polyp size, followed closely by visual estimation. The open biopsy forceps method was the least accurate.

Growth of colorectal polyps: redetection and evaluation of unresected polyps for a period of three years

BACKGROUND, AIMS, AND PATIENTS: In a prospective follow up and intervention study of colorectal polyps, leaving all polyps less than 10 mm in situ for three years, analysis of redetection rate, growth, and new polyp formation was carried out in 116 patients undergoing annual colonoscopy. The findings in relation to growth and new polyp formation were applied to 58 subjects who received placebo.

RESULTS

Redetection rate varied from 75-90% for each year, and was highest in the rectum and sigmoid colon. There was no net change in size of all polyps in the placebo group, however, polyps less than 5 mm showed a tendency to net growth, and polyps 5-9 mm a tendency to net regression in size, both for adenomas and hyperplastic polyps. This pattern was verified by computerised image analysis. Patients between 50 and 60 years showed evidence of adenoma size increase compared with the older patients, and the same was true for those with multiple adenomas (four to five) compared with those with a single adenoma. The new adenomas were significantly smaller and 71% were located in the right side of the colon. Patients with multiple adenomas had more new polyps at all the follow up examinations than patients with a single adenoma. One patient developed an invasive colorectal carcinoma, which may be evolved from a previously overlooked polyp. Two polyps, showing intramucosal carcinoma after follow up for three years, were completely removed, as judged by endoscopy and histological examination.

CONCLUSIONS

The results show that follow up of unresected colorectal polyps up to 9 mm is safe. The consistency of growth retardation of medium sized polyps suggests extended intervals between the endoscopic follow up examinations, but the increased number of new polyps in the proximal colon indicates total colonoscopy as the examination of choice. The growth retardation of the medium sized polyps may partly explain the discrepancy between the prevalence of polyps and the incidence of colorectal cancer.

Secretory component mRNA and protein expression in colorectal adenomas and carcinomas

Secretary component (SC) is expressed basolaterally as a transmembrane protein (pIg receptor) on secretory epithelial cells. As pIg receptor it plays a central role in humoral immunity by mediating the external translocation of dimeric IgA and pentameric IgM. A few case reports have suggested that reduced or absent SC protein expression is associated with diarrhoeal disease, but there is no convincing evidence that a primary pIg receptor deficiency can occur. In this study the relative presence of SC mRNA was determined by Northern blot analysis and related to immunohistochemically determined SC protein expression in 33 colorectal adenomas (31 patients) with increased risk of developing sporadic colorectal cancer, as well as in 19 colorectal carcinomas from 19 patients with such sporadic tumours. In the adenomas, SC mRNA levels were positively related to SC protein expression; both mRNA and SC protein were negatively related to histological grade. Similarly, SC mRNA levels tended to be related to the SC protein expression in the carcinomas. SC mRNA was detected in all adenomas, and only two of ten carcinomas (10.5%) deemed to be SC deficient by immunohistochemistry also lacked SC mRNA expression, suggesting diallelic alterations in the SC-encoding gene (locus PIGR). This possibility agreed with Southern blot analysis performed on a separate sample of 32 other colonic carcinomas in which the diallelic loss of D1S58 (which exhibits a close linkage centromerically to PIGR) was calculated to be 6.4%. Together these findings suggested that reduced SC protein expression in colorectal adenomas might be a transcriptional defect reflecting the degree of cellular dysplasia, whereas absent SC protein expression in colorectal carcinomas might also involve post-transcriptional defects and occasional diallelic gene deletions representing late events in carcinogenesis.

Growth of colorectal polyps: recovery and evaluation of unresected polyps of less than 10 mm, 1 year after detection

BACKGROUND AND METHODS

Colonoscopic 1-year control of polyps of less than 10 mm left in situ was carried out in 103 (89%) of 116 originally examined patients.

RESULTS

Analysis showed an 85% recovery: 91% and 81% for polyps of 5-9 mm and < 5 mm, respectively. The recovery was significantly related to size and localization, whereas the growth rate was inversely correlated to the originally measured diameter. A linear relationship was demonstrated between anus-to-polyp distances 1 year apart, with a normalized agreement index of 0.70. In only 1 of 189 polyps, an increase of diameter to > 10 mm was demonstrated. The 79 new polyps in 52 (50%) of the patients were significantly smaller, more often right-sided, and related to multiplicity of polyps at the initial examination but not to growth of recovered polyps or cleansing status.

CONCLUSION

An acceptable recovery and growth rate of polyps < 10 mm seems to justify the continuation of the study for the remaining 2 years.