Distal colonic hyperplastic polyps do not predict proximal adenomas in asymptomatic average-risk subjects.

The significance of distal colonic hyperplastic polyps was investigated in 482 asymptomatic average-risk subjects, aged 50-75 years, in whom fecal occult blood test results were negative and who underwent screening colonoscopy. The incidence of adenomas in the colon proximal to the sigmoid-descending colon junction in subjects with hyperplastic polyps distal to that point was 18% and was similar to the incidence of proximal colonic adenomas in subjects with no distal colonic polyps (15%). The incidence of proximal colonic adenomas in subjects with no distal colonic adenomas was 38% and was significantly greater than the incidence found in individuals with no distal colonic polyps or only hyperplastic polyps. Our data do not support distal colonic hyperplastic polyps as markers for proximal colonic adenomas in asymptomatic average-risk subjects.     

Glutathione concentrations and glutathione S-transferase activity in human colonic neoplasms

Abstract Tissue concentrations of glutathione (GSH) and the activity of glutathione S-transferases (GST) are relevant to the inactivation of a variety of xenobiotics including carcinogens and anti-neoplastic drugs. In this study, GSH concentrations and GST activity were determined in 25 adenomatous polyps removed at colonoscopy, and in cancer and uninvolved 'normal' mucosa from 58 operative specimens containing colon cancer. We also examined the relationship between GSH concentrations, GST activity and rates of cell proliferation as assessed by flow cytometry. Concentrations of GSH were significantly higher in adenomas ( P = 0.001) and cancer ( P = 0.001) than in uninvolved mucosa while GST activity was significantly higher in cancer ( P = 0.007). There was a positive relationship between GSH concentrations and GST activity in adenomas ( P = 0.001) but not in uninvolved mucosa ( P = 0.06) or cancer ( P = 0.4). Concentrations of GSH and GST activity were independent of results from flow cytometry. The higher concentrations of GSH in colonic neoplasms and the raised activity of GST in cancer may contribute to their resistance to anti-neoplastic drugs.     

A prospective single centre study comparing computed tomography pneumocolon against colonoscopy in the detection of colorectal neoplasms

BACKGROUND AND AIMS: To determine the sensitivity and specificity of computed tomography (CT) pneumocolon in the detection of colorectal neoplasms. METHODS: A total of 201 consecutive patients with colorectal symptoms or requiring surveillance for colorectal neoplasms underwent both conventional colonoscopy and CT pneumocolon. RESULTS: On conventional colonoscopy 13 invasive colorectal carcinomas were detected in 13 patients, and 118 polyps in 63 patients (14 polyps were > or =1 cm in diameter, 25 were 6-9 mm, and 79 were < or =5 mm). CT pneumocolon detected all 13 cancers, two false positive cancers, but only 20 polyps (seven were > or =1 cm). This resulted in a sensitivity of 100% (95% confidence interval (CI) 87-100%) and specificity of 99% (95% CI 97-100%) for detection of invasive carcinoma, and a sensitivity of 73% (95% CI 56-90%) and specificity of 94% (95% CI 91-98%) for detection of invasive carcinoma and/or > or =1 cm polyps. CT pneumocolon also identified invasive carcinoma not seen at colonoscopy because of incomplete examination in three patients, and detected metastases in six colorectal carcinoma patients and extracolonic carcinoma in a further seven patients. CONCLUSIONS: CT pneumocolon had a high sensitivity and specificity for detection of invasive colorectal carcinoma but not colorectal polyps. CT pneumocolon may be suitable for initial investigation of patients with symptoms of colorectal malignancy.     

A modified colorectal screening score for prediction of advanced neoplasia: A prospective study of 5744 subjects

Background and Aim

We validated a modified risk algorithm based on the Asia‐Pacific Colorectal Screening (APCS) score that included body mass index (BMI) for prediction of advanced neoplasia.

Methods

Among 5744 Chinese asymptomatic screening participants undergoing a colonoscopy in Hong Kong from 2008 to 2012, a random sample of 3829 participants acted as the derivation cohort. The odds ratios for significant risk factors identified by binary logistic regression analysis were used to build a scoring system ranging from 0 to 6, divided into “average risk” (AR): 0; “moderate risk” (MR): 1–2; and “high risk” (HR): 3–6. The other 1915 subjects formed a validation cohort, and the performance of the score was assessed.

Results

The prevalence of advanced neoplasia in the derivation and validation cohorts was 5.4% and 6.0%, respectively (P = 0.395). Old age, male gender, family history of colorectal cancer, smoking, and BMI were significant predictors in multivariate regression analysis. A BMI cut‐off at > 23 kg/m² had better predictive capability and lower number needed to screen than that of > 25 kg/m². Utilizing the score developed, 8.4%, 57.4%, and 34.2% in the validation cohort were categorized as AR, MR, and HR, respectively. The corresponding prevalence of advanced neoplasia was 3.8%, 4.3%, and 9.3%. Subjects in the HR group had 2.48‐fold increased prevalence of advanced neoplasia than the AR group. The c‐statistics of the modified score had better discriminatory capability than that using predictors of APCS alone (c‐statistics = 0.65 vs 0.60).

Conclusions

Incorporating BMI into the predictors of APCS score was found to improve risk prediction of advanced neoplasia and reduce colonoscopy resources.     

News in brief

A broad range of modalities for colorectal cancer (CRC) screening are available worldwide. Although recent studies have been demonstrating developments of CRC screening modalities including colonoscopy, computed tomography colonography or colon video capsule colonoscopy remains the gold standard for the early detection of adenoma or CRC. Because patient preferences and availability of resources play an important role in the selection of CRC screening options, further improvement of each screening modality and its associated research is necessary to consider its involvement in clinical practice.     

Screening colonoscopy in asymptomatic average-risk Koreans: analysis in relation to age and sex

BACKGROUND AND AIMS: Although the incidence of colorectal cancer is rising in Asian countries, there are no guidelines for its screening in this region due in part to the lack of epidemiological data regarding colorectal neoplasms. This study aimed to evaluate the prevalence of colorectal neoplasms in average-risk Koreans and to assess the effectiveness of screening colonoscopy in Korea. METHODS: The prevalence of colorectal neoplasms was assessed by primary screening colonoscopy in 5,086 consecutive asymptomatic adults (males 70.5%; age 20-84 years) with no risk factors for colorectal cancer. RESULTS: The overall prevalence of colorectal neoplasms in the 5,086 subjects was 21.9% and this increased linearly with age. Among the 2,435 subjects aged >or=50 years (males 66.7%; mean age 57.7 years), the prevalence of all colorectal neoplasms was 30.2% (males 35.9% vs females 18.7%; P < 0.001), while advanced neoplasms accounted for only 4.1% (males 5.1% vs females 2.0%; P < 0.001). The prevalence of advanced neoplasms in Korean men of a specific age group was similar to that of Korean women in the 10-years older age group. Also, Koreans in a specific age group showed a prevalence of advanced neoplasms similar to that of Westerners in the 10-years younger age group. CONCLUSIONS: Colonoscopy is a useful modality for colorectal cancer screening in Korea, as established in Western countries. However, the screening colonoscopy may begin at an older age for Koreans than for Westerners. Similarly, the optimal starting age for screening in Korean women may be higher than that in men by 10 years.     

Faecal calprotectin levels in a high risk population for colorectal neoplasia

BACKGROUND: Faecal concentrations of the protein calprotectin have been found to be elevated in patients with colorectal neoplasia, suggesting that it might be used as a screening tool for colorectal cancer as well as adenomas. AIMS: To measure the sensitivity and specificity of faecal calprotectin for the detection of adenomas in high risk individuals undergoing colonoscopy. Also, to investigate between and within stool variability of calprotectin concentrations. SUBJECTS: A total of 814 patients planned for colonoscopy were included for the following indications: positive faecal occult blood test, 25; neoplasia surveillance, 605; newly detected polyp, 130; and family risk, 54. METHODS: Two faecal samples from each of two stools were analysed using the PhiCal ELISA test device (Nycomed Pharma AS). RESULTS: Adenoma patients had significantly higher calprotectin levels than normal subjects (median 9.1 (95% confidence interval 7.5-10.1) v 6.6 (5.6-7.4)mg/l). There was no significant decrease in calprotectin levels after polypectomy. Levels in cancer patients were significantly higher than those in all other subgroups (median 17.6 mg/l (11.5-31.0)). With a cut off limit of 10 mg/l, the sensitivity for cancer was 74% and for adenoma 43%. Corresponding specificity values were 64% for no cancer and 67% for no neoplasia (cancer+adenoma). Specificity varied from 71% for one stool sample to 63% for four samples. Stool variability was small, suggesting that two spots from one stool were as discriminative as two spots from each of two stools. CONCLUSIONS: The sensitivity and specificity of faecal calprotectin levels as a marker for colorectal adenoma and carcinoma justifies its use in high risk groups, but specificity is too low for screening of average risk persons. Lack of a decrease in levels after polypectomy may be due to a more widespread leucocyte migration into the intestinal lumen than that at the polyp site, and needs further investigation.     

Age and distal colonic findings determine the yield of advanced proximal neoplasia in Chinese patients with rectal bleeding

BACKGROUND AND AIMS: Few data were available on the optimal diagnostic strategy for Chinese patients with hematochezia. We aimed to evaluate the impact of age and distal colonic findings on the yield of diagnostic strategies in young Chinese patients with hematochezia. METHODS: Consecutive outpatients aged less than 50 years were analyzed using a hypothesized mixed diagnostic strategy to determine the optimal cut-off age for the use of sigmoidoscopy and colonoscopy. The efficacy and cost of the diagnostic strategy and the number of colonoscopies needed to detect one advanced proximal neoplasm (APN) using different cut-off ages were assessed. RESULTS: In the hypothesized mixed diagnostic strategy for young patients, the sensitivities for the detection of APN were 100%, 92% and 75% if the cut-off ages were 30, 35 and 40 years, respectively. The cost needed to detect one APN would be $US 3155, $US 3179 and $US 3497 if the cut-off ages were 30, 35 and 40 years, respectively. Colonoscopy would be performed in 84%, 69% and 51% of patients if the cut-off ages were 30, 35 and 40 years, respectively. CONCLUSION: Colonoscopy should be considered for Chinese patients with rectal bleeding who are aged > or =35 years or those aged <35 years who have adenoma in the distal colon.     

Screening for colorectal neoplasia in asymptomatic patients using flexible fiberoptic sigmoidoscopy

Four hundred seventeen asymptomatic patients with an average age of 52 years underwent screening flexible fiberoptic sigmoidoscopy. Seventy-three polyps were detected in 52 patients with a 17.5 per cent detection rate. Half were above 25 cm and one-third were greater than 1.0 cm in size. Biannual follow-up of these patients is planned to determine the efficacy of this screening procedure combined with removal of all polyps in preventing the development of colorectal cancer.     

Spatial clustering of multiple hyperplastic,adenomatous, and malignant colonic polyps in individual patients

Analysis of relative polyp locations in 426 consecutive patients with multiple colonic polyps found on colonoscopy showed novel findings. First, synchronous and metachronous neoplastic polyps showed spatial clustering in individual patients. For example, patients with their largest neoplasm in the cecum or proximal ascending colon, had 34.3 percent±4.6 percent (standard error) of their other colonic neoplasms in the same location. Second, hyperplastic polyps showed spatial clustering in individuals that was statistically significantly greater than expected from the increased hyperplastic polyp concentration in the rectum and sigmoid. Third, hyperplastic polyps showed spatial clustering with neoplastic polyps; this clustering was similar in magnitude to clustering for exclusively hyperplastic or neoplastic polyps. In contrast, lipomas were not spatially clustered with hyperplastic and neoplastic polyps. The magnitude of clustering between hyperplas and neoplasia showed a closer association between these histologic types than previously appreciated. Because of clustering, regions with prior polyps appear to merit closer surveillance. These findings suggest clinical study, using a randomized controlled clinical trial, of whether a patient who had only rectal and sigmoid adenomas on initial and follow-up colonoscopy should have surveillance with flexible sigmoidoscopy alternating annually with colonoscopy. A patient with a prior cecal adenoma should have surveillance only with a complete colonoscopy or adequate cecal views on barium enema.     

Endoscopy for Hematochezia in Patients Under 50 Years of Age

The optimal strategy for evaluating rectal bleeding in young persons is unknown. This study examines the prevalence of adenomatous neoplasms identified at endoscopy for rectal bleeding. Retrospective cross-sectional analysis was made of patients under 50 years of age undergoing elective outpatient colonoscopy or flexible sigmoidoscopy for hematochezia. In all, 570 patients (309 F/261 M) met our inclusion criteria. The prevalence of neoplasms was 3.8% (95% CI 1.2–8.5%) among persons under 30, 2.8% (95% CI 0.9–6.3%) among persons age 30–39, and 10.9% (95% CI 7.4–15.4%) among persons age 40–49. The prevalence of neoplasms was higher in persons over age 40 (relative risk 3.43, 95% CI 1.70–6.94). Six of seven advanced neoplasms were identified in persons over age 40 (relative risk 7.4, 95% CI 0.89–60.7). In conclusion, the prevalence of colonic neoplasms in patients 40–50 years old with hematochezia is substantial. Among those persons younger than 40 years, the prevalence of colonic neoplasms is significantly lower.