Accuracy of fecal occult blood screening for colorectal neoplasia. A prospective study using Hemoccult and HemoQuant tests

Cost-Effectiveness of Multitarget Stool DNA Testing vs Colonoscopy or Fecal Immunochemical Testing for Colorectal Cancer Screening in Alaska Native People

OBJECTIVE

To estimate the cost-effectiveness of multitarget stool DNA testing (MT-sDNA) compared with colonoscopy and fecal immunochemical testing (FIT) for Alaska Native adults.

PATIENTS AND METHODS

A Markov model was used to evaluate the 3 screening test effects over 40 years. Outcomes included colorectal cancer (CRC) incidence and mortality, costs, quality-adjusted life-years (QALYs), and incremental cost-effectiveness ratios (ICERs). The study incorporated updated evidence on screening test performance and adherence and was conducted from December 15, 2016, through November 6, 2019.

RESULTS

With perfect adherence, CRC incidence was reduced by 52% (95% CI, 46% to 56%) using colonoscopy, 61% (95% CI, 57% to 64%) using annual FIT, and 66% (95% CI, 63% to 68%) using MT-sDNA. Compared with no screening, perfect adherence screening extends life by 0.15, 0.17, and 0.19 QALYs per person with colonoscopy, FIT, and MT-sDNA, respectively. Colonoscopy is the most expensive strategy: approximately $110 million more than MT-sDNA and $127 million more than FIT. With imperfect adherence (best case), MT-sDNA resulted in 0.12 QALYs per person vs 0.05 and 0.06 QALYs per person by FIT and colonoscopy, respectively. Probabilistic sensitivity analyses supported the base-case analysis. Under varied adherence scenarios, MT-sDNA either dominates or is cost-effective (ICERs, $1740-$75,868 per QALY saved) compared with FIT and colonoscopy.

CONCLUSION

Each strategy reduced costs and increased QALYs compared with no screening. Screening by MT-sDNA results in the largest QALY savings. In Markov model analysis, screening by MT-sDNA in the Alaska Native population was cost-effective compared with screening by colonoscopy and FIT for a wide range of adherence scenarios.

Colorectal Cancer-Derived CAT1-Positive Extracellular Vesicles Alter Nitric Oxide Metabolism in Endothelial Cells and Promote Angiogenesis

Accumulating scientific evidences strongly support the importance of cancer-derived extracellular vesicles (EV) in organization of tumor microenvironment and metastatic niches, which are also considered as ideal tools for cancer liquid biopsy. To uncover the full scope of proteomic information packaged within EVs secreted directly from human colorectal cancer, we cultured surgically resected viable tissues and obtained tissue-exudative EVs (Te-EV). Our quantitative profiling of 6,307 Te-EV proteins and 8,565 tissue proteins from primary colorectal cancer and adjacent normal mucosa (n = 17) allowed identification of a specific cargo in colorectal cancer-derived Te-EVs, high-affinity cationic amino acid transporter 1 (CAT1, P = 5.0 × 10^-3, fold change = 6.2), in addition to discovery of a new class of EV markers, VPS family proteins. The EV sandwich ELISA confirmed escalation of the EV-CAT1 level in plasma from patients with colorectal cancer compared with healthy donors (n = 119, P = 3.8 × 10^-7). Further metabolomic analysis revealed that CAT1-overexpressed EVs drastically enhanced vascular endothelial cell growth and tubule formation via upregulation of arginine transport and downstream NO metabolic pathway. These findings demonstrate the potency of CAT1 as an EV-based biomarker for colorectal cancer and its functional significance on tumor angiogenesis. IMPLICATIONS: This study provides a proteome-wide compositional dataset for viable colorectal cancer tissue-derived EVs and especially emphasizes importance of EV-CAT1 as a key regulator of angiogenesis.

Alaska Native Patient and Provider Perspectives on the Multitarget Stool DNA Test Compared With Colonoscopy for Colorectal Cancer Screening

Objective: Alaska Native (AN) people have among the world's highest rate of colorectal cancer (CRC). We assessed perceptions of AN people and their health care providers of a new take-home multitarget stool DNA test (MT-sDNA; Cologuard) relative to colonoscopy. Methods: Cross-sectional surveys of AN people aged 40 to 75 years (mailed) and providers (online). Results: Participants included 1616 AN patients (19% response rate) and 87 providers (26% response rate; 57% AN people). Over half (58%) of patients preferred colonoscopy for CRC screening, while 36% preferred MT-sDNA. Unscreened patients were significantly more likely to state a preference for MT-sDNA than previously screened patients (42% vs 31%, P < .05) as were younger patients (<60 years old) compared with older patients (40% vs 30%, P < .05). Most providers thought that MT-sDNA would improve screening rates (69%), would recommend if available (79%), and be implementable (79%). Perceived barriers differed substantially between patients and providers in both type and magnitude. Leading colonoscopy barriers reported by patients were travel (44%) and bowel preparation (40%), while providers thought that fear of pain (92%) and invasiveness of the test (87%) were the primary barriers. For MT-sDNA, patients' belief that colonoscopy was better (56%) and not knowing how to do the test (40%) were primary barriers, while providers thought stool collection (67%) and having a stool sample in their home (63%) were leading barriers. Conclusions: This study found that MT-sDNA has potential acceptability among AN people and their health care providers. Both groups reported a willingness to use MT-sDNA and did not perceive major barriers to its use. This preference was especially true of unscreened and younger patients. The majority of providers indicated they would use MT-sDNA if available and that it would improve CRC screening rates. In this population, where colonoscopy access is limited, MT-sDNA has the potential to improve CRC screening adherence.

Stool DNA Testing for Screening Detection of Colorectal Neoplasia in Alaska Native People

OBJECTIVE

To assess the accuracy of a multitarget stool DNA test (MT-sDNA) compared with fecal immunochemical testing for hemoglobin (FIT) for detection of screening-relevant colorectal neoplasia (SRN) in Alaska Native people, who have among the world's highest rates of colorectal cancer (CRC) and limited access to conventional screening approaches.

PATIENTS AND METHODS

We performed a prospective, cross-sectional study of asymptomatic Alaska Native adults aged 40-85 years and older undergoing screening or surveillance colonoscopy between February 6, 2012, and August 7, 2014.

RESULTS

Among 868 enrolled participants, 661 completed the study (403 [61%] women). Overall, SRN detection by MT-sDNA (49%) was superior to that by FIT (28%; P<.001); in the screening group, SRN detection rates were 50% and 31%, respectively (P=.01). Multitarget stool DNA testing detected 62% of adenomas 2 cm or larger vs 29% by FIT (P=.05). Sensitivity by MT-sDNA increased with adenoma size (to 80% for lesions ≥3 cm; P=.01 for trend) and substantially exceeded FIT sensitivity at all adenoma sizes. For sessile serrated polyps larger than 1 cm (n=9), detection was 67% by MT-sDNA vs 11% by FIT (P=.07). For CRC (n=10), detection was 100% by MT-sDNA vs 80% by FIT (P=.48). Specificities were 93% and 96%, respectively (P=.03).

CONCLUSION

The sensitivity of MT-sDNA for cancer and larger polyps was high and significantly greater than that of FIT for polyps of any size, while specificity was slightly higher with FIT. These findings could translate into high cumulative neoplasm detection rates on serial testing within a screening program. The MT-sDNA represents a potential strategy to expand CRC screening and reduce CRC incidence and mortality, especially where access to endoscopy is limited.

The promise of methylation on beads for cancer detection and treatment

Despite numerous technical hurdles, the realization of true personalized medicine is becoming a progressive reality for the future of patient care. With the development of new techniques and tools to measure the genetic signature of tumors, biomarkers are increasingly being used to detect occult tumors, determine the choice of treatment and predict outcomes. Methylation of CpG islands at the promoter region of genes is a particularly exciting biomarker as it is cancer-specific. Older methods to detect methylation were cumbersome, operator-dependent and required large amounts of DNA. However, a newer technique called methylation on beads has resulted in a more uniform, streamlined and efficient assay. Furthermore, methylation on beads permits the extraction and processing of miniscule amounts of methylated tumor DNA in the peripheral blood. Such a technique may aid in the clinical detection and treatment of cancers in the future.

Improved 5-year survival of patients with immunochemical faecal blood test-screen-detected colorectal cancer versus non-screening cancers in northern Italy

BACKGROUND

Colorectal cancer screening may reduce disease-related mortality by early-stage detection of cancers.

AIMS

To study the effect of a single immunochemical faecal occult blood test (i-FOBt) screening round on reduction in colorectal cancer-related-mortality among average risk subjects.

METHODS

Comparison of 5-year mortality rates in 3 cohorts from a Northern Italian province: (1) colorectal cancers detected at the 1st biennial round of a mass-screening programme targeting 50-69 years old subjects, (2) non-screening cancers symptomatically diagnosed during the same time period, and (3) cancers detected in the pre-screening biennium. Multivariate analyses were performed with the Cox regression model including tumour node metastasis (TNM) stage at diagnosis, anatomical distribution of cancers, age at diagnosis, gender and patient group. Kaplan-Meyer survival estimates and log-rank test for equality of survivor functions were calculated.

RESULTS

Stage distribution significantly differed between screening and non-screening colorectal cancers: 73% of screen-detected colorectal cancers were stages I and II versus 43% and 40% of non-screening and pre-screening colorectal cancers. Cumulative 5-year mortality rate was significantly lower in screening compared to non-screening or pre-screening colorectal cancers patients (19% versus 37% and 41%, p < 0.001).

CONCLUSIONS

Colorectal cancers were detected at earlier stages in i-FOBT-positive subjects in comparison with non-screening patients; colorectal cancers found at screening had a significantly improved 5-year survival.

Ultra-sensitive liquid biopsy of circulating extracellular vesicles using ExoScreen

Cancer cells secrete small membranous extracellular vesicles (EVs) into their microenvironment and circulation. Although their potential as cancer biomarkers has been promising, the identification and quantification of EVs in clinical samples remains challenging. Here we describe a sensitive and rapid analytical technique for profiling circulating EVs directly from blood samples of patients with colorectal cancer. EVs are captured by two types of antibodies and are detected by photosensitizer-beads, which enables us to detect cancer-derived EVs without a purification step. We also show that circulating EVs can be used for detection of colorectal cancer using the antigen CD147, which is embedded in cancer-linked EVs. This work describes a new liquid biopsy technique to sensitively detect disease-specific circulating EVs and provides perspectives in translational medicine from the standpoint of diagnosis and therapy.

The potential of extracellular vesicles (EVs) as cancer biomarkers is substantial. Here, Yoshioka et al. describe a sensitive technique to analyse EVs directly from blood samples of patients with colorectal cancer, highlighting a liquid biopsy technique with cancer-detection possibilities.

PIAS3 may represent a potential biomarker for diagnosis and therapeutic of human colorectal cancer

Colorectal cancer (CRC) is a challenging problem both for the developed and underdeveloped countries. Despite numerous improvements in early diagnosis and treatment, the incidence and mortality is still keeping in a high level. Molecule targeted therapy has drawn much attention as next generation anticancer agents for diagnosis and therapeutic of CRC. Protein Inhibitor of Activated Signal Transducer and Activators of Transcription 3 (PIAS3) as a novel biomarker has been focused to have a role in the development of malignancy, which was expressed at a higher level in most common malignancies compared with corresponding normal tissues. Furthermore, evidences suggest that the expression of PIAS3 can affect the growth of cancer cells by inhibiting the JAK/STAT and PI3-K/Akt signaling pathways or regulating its SUMO (small-ubiquitin like modifiers) ligase activity in some malignancy. Therefore, we hypothesized that PIAS3 may be a potential biomarker target for early cancer detection and therapeutic of human CRC.

Detection of hypermethylated fibrillin-1 in the stool samples of colorectal cancer patients

Prior studies have demonstrated that analysis of gene promoter methylation in stool samples may be a potential biomarker for noninvasive colorectal cancer detection. Aberrant methylation in gene promoter is common in various cancers, and epigenetic alterations can result in down-regulation or silence of gene expression. Recently, hypermethylation of fibrillin-1 (FBN1) was reported to be associated with colorectal cancer (CRC). In this study, we examined the methylation status of FBN1 in stool samples to test CRC. For the purpose of colorectal cancer detection, we investigated FBN1 hypermethylation in the tissue and stool samples of colorectal cancer patients using methylation-specific polymerase chain reaction. The result is that out of 75 patients with colorectal cancer, 59 (78.7%) exhibited hypermethylated FBN1 in their tumor tissue DNA. We next detected the methylation status of FBN1 in the stool DNA of these patients. The hypermethylated FBN1 occurred in 72% (54/75) of these patients in their stool samples and occurred in 6.7% (2/30) of healthy people (P < 0.001). The results indicated 72.0% sensitivity and 93.3% specificity of the test for detecting CRC by using stool samples. So, the study reveals that hypermethylation status in the promoter of FBN1 is a high specific and sensitive biomarker for colorectal cancer, and detecting hypermethylated FBNI in stool samples is a noninvasive and useful method for screening colorectal cancer.

Application of the fecal microRNA test to the residuum from the fecal occult blood test

OBJECTIVE

Though the fecal occult blood test is used for colorectal cancer screening worldwide, it does not have a particularly high sensitivity for detecting colorectal cancer. Here we investigated the applicability of the fecal microRNA test to fecal samples that had been used for a previous fecal occult blood test and stored under various conditions.

METHODS

Five colorectal cancer patients and five healthy volunteers were enrolled. Fecal samples were stored for 0-5 days at 4°C, room temperature or 37°C. Total RNA was extracted from the fecal occult blood test residuum and microRNA expression was analyzed by real-time reverse transcription polymerase chain reaction.

RESULTS

There were no remarkable differences either in colorectal cancer patients or in controls with regard to the concentration of RNA extracted from the fecal occult blood test residuum in any of the storage groups compared with the samples prepared on day 0 (Group 0). Ribosomal RNA stored at room temperature or 37°C degraded rapidly. In contrast, the ribosomal RNA stored at 4°C remained intact for at least 5 days. The microRNAs in samples stored at 4°C and room temperature were conserved; however, the microRNAs stored at 37°C were significantly degraded compared with Group 0 (P < 0.05). In the residuum stored at 4°C up to 5 days, the relative quantification of miR-106a normalized with miR-24 in colorectal cancer patients was significantly higher than those in healthy volunteers (P < 0.05). In contrast, the quantification of normalized miR-106a was remarkably low in samples stored at room temperature and 37°C.

CONCLUSIONS

Fecal microRNA of sufficient quality for reverse transcription polymerase chain reaction analysis was extracted from the fecal occult blood test residuum stored at 4°C for up to 5 days.

Quantitative profiling of CpG island methylation in human stool for colorectal cancer detection

PURPOSE

The aims of this study were to investigate the use of quantitative CGI methylation data from stool DNA to classify colon cancer patients and to relate stool CGI methylation levels to those found in corresponding tissue samples.

METHODS

We applied a quantitative methylation-specific PCR assay to determine CGI methylation levels of six genes, previously shown to be aberrantly methylated during colorectal carcinogenesis. Assays were performed on DNA from biopsies of "normal" mucosa and stool samples from 57 patients classified as disease-free, adenoma, or cancer by endoscopy, and in tumour tissue from cancer patients. Additionally, CGI methylation was analysed in stool DNA from an asymptomatic population of individuals covering a broad age range (mean = 47 ± 24 years)

RESULTS

CGI methylation levels in stool DNA were significantly higher than in DNA from macroscopically normal mucosa, and a significant correlation between stool and mucosa was observed for ESR1 only. Multivariate statistical analyses using the methylation levels of each CGI in stool DNA as a continuous variable revealed a highly significant (p = 0.003) classification of cancer vs. non-cancer (adenoma + disease-free) patients (sensitivity = 65 %, specificity = 81 %).

CONCLUSION

CGI methylation profiling of stool DNA successfully identified patients with cancer despite the methylation status of CGIs in stool DNA not generally reflecting those in DNA from the colonic mucosa.

Improving colorectal cancer management: the potential of proteomics

Colorectal cancer (CRC) is the third most common cancer worldwide. Successful treatment is heavily dependent on tumor stage at the time of detection, but unfortunately CRC is often only detected in advanced stages. New biomarkers in the form of genes or proteins that can be used for diagnosis, prognostication, follow-up, and treatment selection and monitoring could be of great benefit for the management of CRC. Furthermore, proteins could prove valuable new targets for therapy. Therefore, clinical proteomics has gained a lot of scientific interest in this regard. To get an overall insight into the extent to which this research has contributed to a better management of CRC, we give a comprehensive overview of the results of proteomics research on CRC, focusing on expression proteomics, in other words, protein profiling studies. Furthermore, we evaluate the potential of the discriminating proteins identified in this research for clinical use as biomarkers for (early) diagnosis, prognosis and follow-up of CRC or as targets for new therapeutic regimens.

A combination of faecal tests for the detection of colon cancer: a new strategy for an appropriate selection of referrals to colonoscopy? A prospective multicentre Italian study

INTRODUCTION

Colonoscopy workload for endoscopy services in Western countries is increasing markedly because of the implementation of faecal occult blood-based mass screening programmes against colorectal cancer (CRC). We therefore explored the possibility of using a combination of faecal tests to prioritize the access to colonoscopy with criteria other than symptoms and/or time of referral.

AIMS AND METHODS

We tested a combination of faecal tests [immunochemical faecal occult blood test (i-FOBT), M2-PK, calprotectin] as markers for advanced neoplasia in a selected series of patients requiring colonoscopy for the suspicion of CRC. All the tests were performed in a 1-day stool sample of patients aged 50-80 years, without any dietary restriction, before colonoscopy.

RESULTS

A total of 280 patients' stool single samples were analysed. Forty-seven patients had CRC and 85 patients had one or more advanced adenoma(s) at colonoscopy/histology. CRCs were associated with a highly significant increase (P<0.001) in faecal tumour M2-PK (mean 24.2 kU/l), which correlated with Dukes' staging. For CRC detection, i-FOBT was the test with the highest specificity and positive predictive value (0.89 and 0.53), whereas M2-PK had the highest sensitivity and negative predictive value (0.87 and 0.96). Calprotectin showed performance similar to M2-PK in terms of sensitivity and negative predictive value (0.93), but had lower specificity (0.39). The best combination of tests to predict the risk of CRC in this series was i-FOBT+M2-PK, as in patients showing positivity to both markers, the risk of cancer was as high as 79%.

CONCLUSION

The combination of i-FOBT and M2-PK is a sensitive tool in clinical practice for the appropriate management of waiting lists for colonoscopy, as it allows the classification of patients into different degrees of priority for investigation, according to their foreseeable risk of CRC.

Circulating U2 small nuclear RNA fragments as a novel diagnostic biomarker for pancreatic and colorectal adenocarcinoma

Improved non-invasive strategies for early cancer detection are urgently needed to reduce morbidity and mortality. Non-coding RNAs, such as microRNAs and small nucleolar RNAs, have been proposed as biomarkers for non-invasive cancer diagnosis. Analyzing serum derived from nude mice implanted with primary human pancreatic ductal adenocarcinoma (PDAC), we identified 15 diagnostic microRNA candidates. Of those miR-1246 was selected based on its high abundance in serum of tumor carrying mice. Subsequently, we noted a cross reactivity of the established miR-1246 assays with RNA fragments derived from U2 small nuclear RNA (RNU2-1). Importantly, we found that the assay signal discriminating tumor from controls was derived from U2 small nuclear RNA (snRNA) fragments (RNU2-1f) and not from miR-1246. In addition, we observed a remarkable stability of RNU2-1f in serum and provide experimental evidence that hsa-miR-1246 is likely a pseudo microRNA. In a next step, RNU2-1f was measured by qRT-PCR and normalized to cel-54 in 191 serum/plasma samples from PDAC and colorectal carcinoma (CRC) patients. In comparison to 129 controls, we were able to classify samples as cancerous with a sensitivity and specificity of 97.7% [95% CI = (87.7, 99.9)] and 90.6% [95% CI = (80.7, 96.5)], respectively [area under the ROC curve 0.972]. Of note, patients with CRC were detected with our assay as early as UICC Stage II with a sensitivity of 81%. In conclusion, this is the first report showing that fragments of U2 snRNA are highly stable in serum and plasma and may serve as novel diagnostic biomarker for PDAC and CRC for future prospective screening studies.

Efficacy of a nationwide screening colonoscopy program for colorectal cancer

BACKGROUND & AIMS

Screening colonoscopy examinations for colorectal cancer are offered in the United States and some European countries. Data on results and adverse effects of screening colonoscopy are limited. In autumn 2002, colonoscopy was introduced as part of a nationwide cancer screening program in Germany; it was offered to the general population for individuals 55 years of age or older. We collected and analyzed data from this program.

METHODS

We performed a prospective cross-sectional study, collecting results from 2,821,392 screening colonoscopies performed at more than 2100 practices by highly qualified endoscopists in Germany from January 2003 to December 2008. Data on participation, colorectal adenoma and cancer detection, and complications were collected using standardized documentation forms. The data generated were centrally processed and evaluated.

RESULTS

The cumulative participation rate was 17.2% of eligible women and 15.5% of eligible men 55-74 years old. The adenoma detection rate (ADR) was 19.4%, with a higher rate in men (25.8% vs 16.7% in women). Advanced adenomas were found in 6.4% of patients. Carcinomas were detected in 25,893 subjects (0.9%); most were of an early UICC stage (I, 47.3%; II, 22.3%; III, 20.7%; IV, 9.6%). The ADRs for gastroenterologists and nongastroenterologists were 25.1% and 22.3%, respectively (adjusted odds ratio, 1.18; 95% confidence interval, 1.16-1.21). The overall complication rate was 2.8/1000 colonoscopies, and the rate of serious complications was 0.58/1000 colonoscopies.

CONCLUSIONS

A nationwide colonoscopy screening program that uses highly qualified endoscopists can detect a significant number of adenomas and early-stage carcinomas. The ADR for gastroenterologists was higher than for nongastroenterologists.

Stool DNA screening for colorectal neoplasia: biological and technical basis for high detection rates

Colorectal cancer (CRC), the second most common cause of cancer-related mortality worldwide, is preventable with effective screening and removal of precursor lesions. Yet, screening efforts have been hampered by low participation rates and by performance limitations of the screening tools themselves. Stool DNA testing has emerged as a biologically rational and user-friendly strategy for the non-invasive detection of both CRC and critical precursor lesions. Unlike most conventional screening tools, stool DNA testing detects proximal and distal colorectal neoplasms equally well. Several key technical advances have led to increasingly accurate approaches for stool DNA testing including use of a DNA preservative buffer with stool collection, efficient target capture and amplification methods, broadly informative marker panels, and automated assay components. Based on recent studies, advanced multi-marker stool DNA tests including methylated markers, mutation markers and an assessment of faecal haemoglobin have been shown to detect CRC at sensitivities of 85% and higher and adenomas >1 cm at 60% and higher in a case-control environment. If the high accuracy of multi-marker stool tests is corroborated in multicentre screening studies on average-risk persons currently underway, then these stool tests could influence our CRC screening paradigm.This review discusses the biological basis, key technical advances, and recent clinical performance validation of stool DNA testing.

Next-generation stool DNA test accurately detects colorectal cancer and large adenomas

BACKGROUND & AIMS

Technical advances have led to stool DNA (sDNA) tests that might accurately detect neoplasms on both sides of the colorectum. We assessed colorectal neoplasm detection by a next-generation sDNA test and effects of covariates on test performance.

METHODS

We performed a blinded, multicenter, case-control study using archived stool samples collected in preservative buffer from 252 patients with colorectal cancer (CRC), 133 with adenomas ≥ 1 cm, and 293 individuals with normal colonoscopy results (controls); two-thirds were randomly assigned to a training set and one-third to a test set. The sDNA test detects 4 methylated genes, a mutant form of KRAS, and the α-actin gene (as a reference value) using quantitative, allele-specific, real-time target and signal amplification; it also quantifies hemoglobin. We used a logistical model to analyze data.

RESULTS

The sDNA test identified 85% of patients with CRC and 54% of patients with adenomas ≥1 cm with 90% specificity. The test had a high rate of detection for all nonmetastatic stages of CRC (aggregate 87% detection rate for CRC stages I-III). Detection rates increased with adenoma size: 54% ≥ 1 cm, 63% >1 cm, 77% >2 cm, 86% >3 cm, and 92% >4 cm (P < .0001). Based on receiver operating characteristic analysis, the rate of CRC detection was slightly greater for the training than the test set (P = .04), whereas the rate of adenoma detection was comparable between sets. Sensitivities for detection of CRC and adenoma did not differ with lesion site.

CONCLUSIONS

Early-stage CRC and large adenomas can be detected throughout the colorectum and with high levels of accuracy by the sDNA test. Neoplasm size, but not anatomical site, affected detection rates. Further studies are needed to validate the findings in a larger population and optimize the sDNA test.

Iron homeostasis and distal colorectal adenoma risk in the prostate, lung, colorectal, and ovarian cancer screening trial

Red meat consumption has been positively associated with colorectal cancer; however, the biological mechanism underlying this relationship is not understood. Red meat is a major source of iron, which may play a role in colorectal carcinogenesis via increased crypt cell proliferation, cytotoxicity, and endogenous N-nitrosation. In a nested case-control study within the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial, we prospectively evaluated multiple iron exposure parameters, including dietary intake and serum measures of iron, ferritin, transferrin, total iron binding capacity (TIBC), and unsaturated iron binding capacity (UIBC) in relation to incident colorectal adenoma in 356 cases and 396 matched polyp-free controls. We also investigated variation in eight key genes involved in iron homeostasis in relation to colorectal adenoma in an additional series totaling 1,126 cases and 1,173 matched controls. We observed a positive association between red meat intake and colorectal adenoma [OR comparing extreme quartiles (OR(q4-q1)) = 1.59, 95% CI = 1.02-2.49, P(trend) = 0.03]. Serum TIBC and UIBC were inversely associated with colorectal adenoma (OR(q4-q1) = 0.57, 95% CI = 0.37-0.88, P(trend) = 0.03; and OR(q4-q1) = 0.62, 95% CI = 0.40-0.95, P(trend) = 0.04, respectively). Colorectal adenoma was not associated with serum ferritin, iron, or transferrin saturation or with polymorphisms in genes involved in iron homeostasis. Serum TIBC and UIBC, parameters that have a reciprocal relationship with overall iron load, were inversely related to colorectal adenoma, suggesting that individuals with lower iron status have a reduced risk of developing colorectal adenoma.

Novel methylation panel for the early detection of colorectal tumors in stool DNA

BACKGROUND

Previous studies showed that the assessment of promoter hypermethylation of a limited number of genes in tumor biopsies may identify the majority of colorectal tumors. This study aimed to assess the clinical usefulness of a panel of methylation biomarkers in stool DNA in the identification of colorectal tumors, using methylation-specific melting curve analysis (MS-MCA), a technique that simultaneously analyzes all cytosine-phosphate-guanine (CpG) residues within a promoter.

MATERIALS AND METHODS

The promoter methylation status of 4 tumor-related genes (RARB2, p16INK4a, MGMT, and APC) was analyzed in DNA stool samples and corresponding tissues in an initial set of 12 patients with newly diagnosed primary colorectal carcinomas and 20 patients with newly diagnosed colorectal adenomas, using methylation-specific polymerase chain reaction. Results were replicated in a set of 82 patients (20 healthy subjects, 16 patients with inflammatory bowel disease (IBD), 20 patients with adenomas, and 26 patients with carcinomas), using MS-MCA analyses.

RESULTS

In the initial set, >or= 1 positive methylation marker was detected in the stools of 9 of 12 patients (75%) with carcinomas and 12 of 20 patients (60%) with adenomas, with no false-positive results. Stool analyses missed 7 methylated lesions (25%). In the replication set, stool DNA testing detected 16 of 26 carcinomas (62%) and 8 of 20 adenomas (40%). The MS-MCAs missed 14 methylated tumors (37%). No aberrant methylation was evident in healthy subjects, but the RARB2 marker was positive in 2 of 15 stool samples (13%) of patients with IBD.

CONCLUSION

Analysis via MS-MCA of a panel of methylation markers in stool DNA may offer a good alternative in the early, noninvasive detection of colorectal tumors.

Identification of endothelial cell-specific molecule-1 as a potential serum marker for colorectal cancer

No ideal serum markers for screening colorectal cancer (CRC) have been identified. The aim of this study was to determine the usefulness of endothelial cell-specific molecule-1 (ESM-1) as a serum marker for CRC. Illumina microarray was carried out to search CRC-related biomarkers. cDNA microarray detected that ESM-1 was one of the overexpressed genes in CRC. Overexpression of ESM-1 mRNA was confirmed in tissues of CRC by RT-PCR and real-time PCR. Immunohistochemical staining showed strong expression of ESM-1 in the cytoplasm of tumor cells. Overexpression of ESM-1 in human serum with CRC was found by Western blot analysis. For quantitative analysis of ESM-1 in serum, we determined the ESM-1 levels in serum specimens using an ELISA kit. We showed that the ESM-1 levels in the serum of patients with CRC were significantly elevated (70.1 ± 29.7 pg/mL) compared to healthy subjects (29.7 ± 14.9 pg/mL). The accuracy, sensitivity, and specificity of ESM-1 for CRC were 0.94, 99%, and 73%, respectively, by receiver operating characteristics curve analysis. The positive predictive value and negative predictive value were 63% and 95%, respectively. The likelihood ratios of a positive or negative test result were 73 and 0.27, respectively. When analyzed with a Cox regression model, a higher serum ESM-1 level (≥76.0 pg/mL) was correlated with poor prognosis. This study suggests that expression of ESM-1 is increased in tissue and serum of CRC patients and that ESM-1 can be used as a potential serum marker for the early detection of CRC.

Early detection of colorectal cancer with faecal occult blood test screening

BACKGROUND

Faecal occult blood test (FOBT) screening has been shown to decrease the incidence and mortality from colorectal cancer. This study compared the stage profile of patients with colorectal cancer diagnosed at the first FOBT screening round with that of an unscreened control group.

METHODS

Subjects aged 60-64 years were allocated randomly to biennial FOBT screening (52 998 subjects) or a control group (53 002) in a Finnish prospective public health policy in 2004-2006. FOBT was performed with a guaiac test. At the end of 2007 the screened and control populations were linked to the Finnish Cancer Registry database, and the colonoscopic findings in the screen positives were analysed.

RESULTS

Early-stage colorectal cancer was observed in 52 per cent of the FOBT-positive subjects, in 42.2 per cent of the total screened population and in 38 per cent of the control population (P = 0.191 for FOBT positives, P = 0.592 for total screened population). The prevalence of adenomas and colorectal cancer was 31.5 and 8.2 per cent respectively among the 806 subjects with a positive FOBT. Some 27.3 per cent of all colorectal tumours in the screened population were interval cancers. The tumour was located in the right colon in 28.9 per cent of the screened subjects and 22 per cent of controls (P = 0.255).

CONCLUSION

Biennial FOBT screening improves detection of colorectal cancer at the first screening round, but the high percentage of interval cancers is a cause for concern.

When budgets are tight, there are better options than colonoscopies for colorectal cancer screening

A critical challenge facing cancer screening programs, particularly those aimed at uninsured people with low incomes, is choosing the screening test that makes the most efficient use of limited budgets. For colorectal cancer screening, there is growing momentum to use colonoscopy, which is an expensive test. In this study, we modeled scenarios to assess whether the use of fecal occult blood tests or colonoscopy provides the most benefit under conditions of budget constraints. We found that although colonoscopy is more accurate, under most scenarios, fecal occult blood tests would result in more individuals' getting screened, with more life-years gained.

CT colonography: coming of age

OBJECTIVE

The purpose of this article is to highlight key issues in CT colonography (CTC) for radiologists so they can represent the technology accurately to referring physicians and provide a perspective that will hopefully augment best care for their patients.

CONCLUSION

With publication of the National CT Colonography Trial and the endorsement of CTC for screening by a multisociety task force that included the American Cancer Society, American College of Radiology, and U.S. Multisociety Task Force on Colorectal Cancer, the clinical validation of CTC has been completed, and CTC is now ready for widespread clinical application. Radiologists must be skilled in CTC and knowledgeable about colorectal cancer screening issues.

Diagnosis of rectal cancer by electromagnetic interactions: preliminary results

OBJECTIVES

Although colonoscopy is effective in screening for colorectal cancer, its high cost and low compliance rates have encouraged a search for different methods. Our study was designed to evaluate the feasibility of rectal cancer detection using a nonlinear tuneable oscillator (TRIMprob), a recently developed device for detecting differences in electromagnetic properties of cancerous and normal tissues.

METHODS

We tested 228 patients (115 male and 113 female) between March and September 2006: 114 patients with rectal cancer diagnosed on colonoscopy and 114 patients with negative colonoscopy results. The TRIMprob probe was moved over the surface of the pelvic area from the back and the front, with the patient standing, normally dressed, between the operator and the system receiver. The signal variation of three spectral lines, for 465-MHz, 930-MHz, and 1395-MHz frequencies was recorded for each of six probe positions.

RESULTS

Analysis of resonance values showed that only the 465-MHz frequency differentiated patients with rectal cancer from those without cancer at all six probe positions (P < 0.001). With a cutoff value of 50 arbitrary units, the area under the receiver operating characteristic curve was 0.94 (specificity, 85 percent; sensitivity, 94 percent).

CONCLUSIONS

The TRIMprob test discriminates well between patients with normal rectal tissue and those with malignant lesions. These preliminary results confirm that electromagnetic detection of rectal cancer is possible and suggest this method of extracorporeal scanning may be useful as a first-level screening tool.

Detection of Colorectal Cancer by Serum and Tissue Protein Profiling: A Prospective Study in a Population at Risk

Colorectal cancer (CRC) is the second most common cause of cancer-related death in Europe and its prognosis is largely dependent on stage at diagnosis. Currently, there are no suitable tumour markers for early detection of CRC. In a retrospective study we previously found discriminative CRC serum protein profiles with surface enhanced laser desorption ionisation—time of flight mass spectrometry (SELDI-TOF MS). We now aimed at prospective validation of these profiles. Additionally, we assessed their applicability for follow-up after surgery and investigated tissue protein profiles of patients with CRC and adenomatous polyps (AP). Serum and tissue samples were collected from patients without known malignancy with an indication for colonoscopy and patients with AP and CRC during colonoscopy. Serum samples of controls (CON; n = 359), patients with AP (n = 177) and CRC (n = 73), as well as tissue samples from AP (n = 52) and CRC (n = 47) were analysed as described previously. Peak intensities were compared by non-parametric testing. Discriminative power of differentially expressed proteins was assessed with support vector machines (SVM). We confirmed the decreased serum levels of apolipoprotein C-1 in CRC in the current population. No differences were observed between CON and AP. Apolipoprotein C-I levels did not change significantly within 1 month post-surgery, although a gradual return to normal levels was observed. Several proteins differed between AP and CRC tissue, among which a peak with similar mass as apolipoprotein C-1. This peak was increased in CRC compared to AP. Although we prospectively validated the serum decrease of apolipoprotein C-1 in CRC, serum protein profiles did not yield SVM classifiers with suitable sensitivity and specificity for classification of our patient groups.

Performance characteristics and comparison of two fecal occult blood tests in patients undergoing colonoscopy

We investigated the use of a new type of FOBT (EZ-Detect) that uses the blood's pseudo-peroxidase activity as an enzymatic catalyst, in a one-step chromogen-substrate system performed by the patient. Asymptomatic patients >/=50 years old received three Hemoccult II (HO) cards and three EZ-Detect (EZ) packages to be used in three consecutive bowel movements. Sensitivity, specificity, positive predictive value, and negative predictive value for detection of colorectal neoplasia was calculated. The study included 207 patients, with a mean age of 58.9 years. Diagnostic accuracy for detection of adenomas was similar for the EZ and HO tests (66.7% vs. 71.0%; P=0.48), while for advanced adenomas diagnostic accuracy for the EZ and HO tests was 86.0% vs. 94.2% (P=0.01), respectively. Most patients preferred the EZ test (92% vs. 8%). We conclude that the EZ test has a diagnostic profile similar to that of the HO test for identification of adenomas; however, for advanced adenomas the diagnostic accuracy was slightly better for the HO. The EZ test was preferred by most patients, which may increase colorectal cancer screening compliance.

Colorectal cancer screening

Colorectal cancer is a major public health burden worldwide. There is clear-cut evidence that screening will reduce colorectal cancer mortality and the only contentious issue is which screening tool to use. Most evidence points towards screening with fecal occult blood testing. The immunochemical fecal occult blood tests have a higher sensitivity than the guaiac-based tests. In addition, their automation and haemoglobin quantification allows a threshold for colonoscopy to be selected that can be accommodated within individual health care systems.

Screening for colorectal cancer in Uruguay with an immunochemical faecal occult blood test

An observational prospective study was carried out in Uruguay to evaluate the feasibility of colorectal cancer screening using immunochemical faecal occult blood tests with no dietary restrictions in an average-risk population. An automated system was used for processing the samples with a cut-off haemoglobin level of 100 ng/ml. Of the 11,734 study participants who received an immunochemical test kit (OC-Hemodia), 10,573 (90.1%) returned samples for screening. The results of 1170 (11.1%) of the responders were positive. Subsequently, colonoscopy was performed on 879 (75.1%) of the participants with a positive test result and showed neoplasia in 330 participants. Fifty four had advanced cancer, 47 had early cancer, 131 had high-risk adenoma and 98 had low-risk adenoma. The detection rates and the positive predictive values were 0.95 and 8.6% for cancer, and 1.24 and 11.2% for high-risk adenoma, respectively. The high compliance and high detection rates for cancer and high-risk adenoma achieved in the colorectal cancer screening programme verifies the feasibility of an immunochemical faecal occult blood test in screening an average-risk population in Uruguay, a country with a small population, but with high morbidity and mortality rates for this disease.

A comparative study of three fecal occult blood tests in upper gastrointestinal bleeding

The purpose of this study was to evaluate the performance characteristics of three fecal occult blood tests (FOBTs): the chemical o-toluidine test, the immunochemical OC-Hemodia test, and the immunochromatographic Quick Chaser Occult Blood (QCOB) test, which detect human hemoglobin and transferrin simultaneously in cases of upper gastrointestinal (GI) bleeding. Included were 48 FOBT specimens in 48 consecutive admission cases of upper GI bleeding (endoscopy confirmed). We excluded those fecal specimens with an obvious tarry and bloody appearance. The QCOB test revealed the highest positive rates of 33/48 (68.8%), and significantly higher positive rates than that of the OC-Hemodia test and o-toluidine test (p < 0.025 and < 0.01, respectively). In the patient group with upper GI bleeding due to gastric and duodenal ulcers, the QCOB test had higher positive rates (68.6%) than did the o-toluidine test (34.3%) (p < 0.01). There was no fecal specimen that was positive for the o-toluidine test or OC-Hemodia test and was negative for the QCOB test. Our results reveal that the QCOB test has significantly higher positive rates of fecal occult blood than either the OC-Hemodia test or o-toluidine test. The QCOB test is better than the other two tests for detecting occult blood in patients with upper GI bleeding.

Colorectal cancer (CRC) screening using sigmoidoscopy followed by colonoscopy: a feasibility and efficacy study on a cancer institute based population

BACKGROUND

Advanced distal neoplasia found at sigmoidoscopy could be the marker for more proximal lesions.

PATIENTS AND METHODS

In the setting of a screening clinic, subjects underwent flexible sigmoidoscopy. If no significant lesion was found, sigmoidoscopy was planned after 5 years. If an advanced neoplasia was found, colonoscopy was performed just after the first sigmoidoscopy and at 1, 3 and 5 years. If a non-advanced neoplasia was found, sigmoidoscopy was performed at 1, 3 and 5 years and followed by colonoscopy if advanced lesion was found.

RESULTS

At first screening 1704/1912 (88%) subjects had a negative sigmoidoscopy, 104 (5.4%) had an advanced neoplasia, 96 (6%) had a non-advanced neoplasia and eight (0.4%) had invasive colorectal cancer (CRC). At follow-up examinations at 1, 3 and 5 years, among 170 subjects with advanced and non-advanced neoplasia, one developed invasive CRC and 47 (31.6%), advanced neoplasia. At 5 years, among 718 first negative sigmoidoscopies, 572 (80%) were confirmed negative and 97 (14%) had advanced neoplasia. Colorectal cancer status at 5 years could be checked for interval cancers in 97% of subjects and no CRC was diagnosed in subjects who did not attend sigmoidoscopy at 5 years. Comparison of the incidence of invasive CRC to the data of registries of the Netherlands and Luxembourg suggested that the incidence of CRC was decreased by 36%-46%. Seven of the nine CRCs were Duke's A and the two others were Duke's B and C.

CONCLUSIONS

Screening with sigmoidoscopy followed by colonoscopy in case of positive sigmoidoscopy leads to substantial decreases in the incidence of CRC. Most CRCs found are at an early, curable stage of their development.

Cost-effectiveness analysis of colorectal cancer screening with stool DNA testing in intermediate-incidence countries

Background

The aim of this study is to compare the cost-effectiveness of screening with stool DNA testing with that of screening with other tools (annual fecal occult blood testing, flexible sigmoidoscopy every 5 years, and colonoscopy every 10 years) or not screening at all.

Methods

We developed a Markov model to evaluate the above screening strategies in the general population 50 to 75 years of age in Taiwan. Sensitivity analyses were performed to assess the influence of various parameters on the cost-effectiveness of screening. A third-party payer perspective was adopted and the cost of $13,000 per life-year saved (which is roughly the per capita GNP of Taiwan in 2003) was chosen as the ceiling ratio for assessing whether the program is cost-effective.

Results

Stool DNA testing every three, five, and ten years can reduce colorectal cancer mortality by 22%, 15%, and 9%, respectively. The associated incremental costs were $9,794, $9,335, and $7,717, per life-year saved when compared with no screening. Stool DNA testing strategies were the least cost-effective with the cost per stool DNA test, referral rate with diagnostic colonoscopy, prevalence of large adenoma, and discount rate being the most influential parameters.

Conclusion

In countries with a low or intermediate incidence of colorectal cancer, stool DNA testing is less cost-effective than the other currently recommended strategies for population-based screening, particularly targeting at asymptomatic subjects.

Three-dimensional MR and axial CT colonography versus conventional colonoscopy for detection of colon pathologies

AIM: To evaluate the sensitivity and specificity of MR colonography (MRC) and CT performance in detecting colon lesions, and to compare their sensitivity and specificity with that of conventional colonoscopy.

METHODS: Forty-two patients suspected of having colonic lesions, because of rectal bleeding, positive fecal occult blood test results or altered bowel habits, underwent the examinations. After insertion of a rectal tube, the colon was filled with 1000-1500 mL of a mixture of 9 g/L NaCl solution, 15-20 mL of 0.5 mmol/L gadopentetate dimeglumine and 100 mL of iodinized contrast material. Once colonic distension was achieved, three-dimensional gradient-echo (3D-GRE) sequences for MR colonography and complementary MR images were taken in all cases. Immediately after MR colonography, abdominal CT images were taken by spiral CT in the axial and supine position. Then all patients were examined by conventional colonoscopy (CC).

RESULTS: The sensitivity and specificity of MRC for colon pathologies were 96.4% and 100%, respectively. The percentage of correct diagnosis by MRC was 97.6%. The sensitivity and specificity of CT for colon pathologies were 92.8%, 100%, respectively. The percentage of correct diagnosis by CT was 95.2%.

CONCLUSION: In detecting colon lesions, MRC achieved a diagnostic accuracy similar to CC. However, MRC is minimally invasive, with no need for sedation or analgesics during investigation. There is a lower percentage of perforation risk, and all colon segments can be evaluated due to multi-sectional imaging availability; intramural, extra-intestinal components of colonic lesions, metastasis and any additional lesions can be evaluated easily. MRC and CT colonography are new radiological techniques that promise to be highly sensitive in the detection of colorectal mass and inflammatory bowel lesions.

Colorectal cancer follow-up in 2005

The main goal in monitoring patients after the treatment of colorectal cancer is to improve survival through the early identification and treatment of metastatic or locally recurrent disease. Although the results of several randomized, controlled trials have identified a survival benefit associated with careful follow-up, specific testing strategies to maximize survival while minimizing cost and patient inconvenience have not been identified. There is, therefore, great variability in the types, number, and frequency of tests ordered to follow these patients. This article reviews the level-I data avail-able regarding the efficacy of follow-up, the specific tests commonly used, and issues of costs and patient satisfaction, and provides a summary of the available societal guidelines concerning colorectal cancer follow-up.

Identification of serum proteins discriminating colorectal cancer patients and healthy controls using surface-enhanced laser desorption ionisation-time of flight mass spectrometry

AIM: To detect the new serum biomarkers for colorectal cancer (CRC) by serum protein profiling with surface-enhanced laser desorption ionisation - time of flight mass spectrometry (SELDI-TOF MS).

METHODS: Two independent serum sample sets were analysed separately with the ProteinChip technology (set A: 40 CRC + 49 healthy controls; set B: 37 CRC + 31 healthy controls), using chips with a weak cation exchange moiety and buffer pH 5. Discriminative power of differentially expressed proteins was assessed with a classification tree algorithm. Sensitivities and specificities of the generated classification trees were obtained by blindly applying data from set A to the generated trees from set B and vice versa. CRC serum protein profiles were also compared with those from breast, ovarian, prostate, and non-small cell lung cancer.

RESULTS: Mass-to-charge ratios (m/z) 3.1×10³, 3.3×10³, 4.5×10³, 6.6×10³ and 28×10³ were used as classifiers in the best-performing classification trees. Tree sensitivities and specificities were between 65% and 90%. Most of these discriminative m/z values were also different in the other tumour types investigated. M/z 3.3×10³, main classifier in most trees, was a doubly charged form of the 6.6×10³-Da protein. The latter was identified as apolipoprotein C-I. M/z 3.1×10³ was identified as an N-terminal fragment of albumin, and m/z 28×10³ as apolipoprotein A-I.

CONCLUSION: SELDI-TOF MS followed by classification tree pattern analysis is a suitable technique for finding new serum markers for CRC. Biomarkers can be identified and reproducibly detected in independent sample sets with high sensitivities and specificities. Although not specific for CRC, these biomarkers have a potential role in disease and treatment monitoring.

Emerging technologies in colorectal cancer screening

CRC is a preventable disease through early detection, yet screening rates remain low and mortality rates remain high. The discomfort associated with the preparation and performance of some of the currently available screening modalities and the lack of public awareness about CRC and screening procedures likely account for low rates of screening. CT colonography and stool DNA testing are new promising screening technologies that are less invasive, accurate, and suitable for the public more than the current screening procedures. Before both tests can be promoted for population-based screening programs, several issues that have been detailed in this article must be addressed further, including technical improvements for improving accuracy, development of virtual preparation, test availability, patient and provider acceptability and cost-effectiveness for CTC, and identifying the optimal combination of molecular targets for stool DNA testing. The year 2005 will tell us if the ideal technology from the public health point of view was achieved. A skill-independent, anesthesia-free, self-propelling, self-navigating miniaturized endoscopic device that may move along the entire length of the colon may change the natural history of CRC. We should aim to achieve a new definition of CRC--a rare disease occurring in a subset of the population who has not been screened for the disease.

Magnetic resonance colonography versus colonoscopy as a diagnostic investigation for colorectal cancer: a meta-analysis

AIMS

Magnetic resonance colonography (MRC) is emerging as a potential complementary investigation for the diagnosis of colorectal cancer (CRC) and also for benign pathology such as diverticular disease. A meta-analysis reporting the use of MRC is yet to be performed. The aim of this study was to evaluate the diagnostic accuracy of MRC compared with the gold-standard investigation, conventional colonoscopy (CC).

METHODS

A literature search was carried out to identify studies containing comparative data between MRC findings and CC findings. Quantitative meta-analysis for diagnostic tests was performed, which included the calculation of independent sensitivities, specificities, diagnostic odds ratios, the construction of summary receiver operating characteristic (SROC) curves, pooled analysis and sensitivity analysis. The study heterogeneity was evaluated by the Q-test using a random-effect model to accommodate the cluster of outcomes between individual studies.

RESULTS

In all, 8 comparative studies were identified, involving 563 patients. The calculated pooled sensitivity for all lesions was 75% (95% CI: 47% to 91%), the specificity was 96% (95% CI: 86% to 98%) and the area under the ROC curve was 90% (weighted). On sensitivity analysis, MRC had a better diagnostic accuracy for CRC than for polyps, with a sensitivity of 91% (95% CI: 97% to 91%), a specificity of 98% (95% CI: 66% to 99%) and an area under the ROC curve of 92%. There was no significant heterogeneity between the studies with regard to the diagnostic accuracy of MRC for CRC.

CONCLUSION

This meta-analysis suggests that MRC is an imaging technique with high discrimination for cases presenting with colorectal cancer. The exact diagnostic role of MRC needs to be clarified (e.g. suitable for an elderly person with suspected CRC). Further evaluation is necessary to refine its applicability and diagnostic accuracy in comparison with other imaging methods such as computed tomography colonography.

Correlates of colorectal cancer screening compliance among urban Hispanics

Colorectal cancer (CRC) is the second most common cancer among Latinos; screening can reduce mortality from CRC. The aims of this study are; to assess the current compliance with free colorectal cancer screening among Hispanic women who are participating in a national breast and cervical cancer screening program (NBCCEDP), and to examine the effects of a set of key constructs from the HBM and the TPB on compliance with the Fecal Occult Blood Test (FOBT). We consecutively recruited 950 women from among those attending an initial appointment at an NBCCEDP site in northern Manhattan, and administered a questionnaire. Patients were offered a free Hemoccult kit, alongside instructions and print materials. The rate of FOBT compliance (in kit return) was 77.3%. Fatalism remained a statistically significant influence on FOBT compliance in the multivariate models, and there was a trend for higher FOBT return among West Indies women (primarily from the Dominican Republic). The findings of this study demonstrate the feasibility and acceptability of distributing FOBT kits through an existing national program for cancer screening of women. The results justify replication in a more heterogeneous group of Hispanics, with longer-term followup.

Virtual colonoscopy by MRI: state-of-the-art and future directions

MR colonography has been shown to be an appropriate diagnostic tool for the detection of colorectal lesions. The technique is based on the acquisition of T1-weighted sequences after the administration of water enema and the intravenous administration of paramagnetic contrast. This article describes the technical requirements for MR colonoscopy and the procedures of data acquisition and image interpretation. The advantages and drawbacks of MR colonoscopy also are outlined.

Screening and surveillance of colorectal cancer

Although colorectal cancer (CRC) is the second leading cause of cancer deaths in the United States, it is preventable. Screening modalities include fecal occult blood testing, flexible sigmoidoscopy, double-contrast barium enema, and colonoscopy. Colonoscopy allows effective detection and removal of precursor adenomatous polyps and is the dominant CRC screening modality. Emerging technologies include CT and MR colonography and fecal DNA tests. Effective and cost-effective surveillance after polypectomy and curative CRC resection requires balancing the protective effect of polypectomy while maximizing intervals between examinations; thus, estimation of the risk of recurrence determines the intensity of surveillance for individual patients.

Tumor markers and colorectal cancer: utility in management

Colorectal cancer (CRC) is a leading cause of morbidity and mortality. Although genetic testing can screen for rare hereditary CRC syndromes, there is no ideal means of screening for sporadic forms of CRC. This review will focus on markers that are currently used in the management of sporadic CRC and their limitations, as well as possible future clinical applications.

Review article: balancing the ideal versus the practical-considerations of colorectal cancer prevention and screening

Colorectal cancer is responsible for over 500 000 deaths annually world-wide. Death from colorectal cancer is preventable, primarily through early diagnosis of disease that has not metastasized. The disease itself may be prevented by the detection and removal of colorectal adenomas, from which more than 95% of colorectal cancers arise. Currently there are several screening methods for the disease. These include faecal occult blood tests, sigmoidoscopy, barium enema and colonscopy as well as emerging methods of virtual colonoscopy and faecal DNA testing. While direct and indirect evidence support the efficacy of these tests they differ from each other in their sensitivity, specificity, cost, and safety. Various professional organizations in different geographical regions of the world have published recommendations on which screening methods to use and when in patients at average- or high-risk. The challenge in reducing the incidence and mortality of this disease lies in increasing accessibility to and compliance with screening and delivery within a quality assured programme.

Options for screening for colorectal cancer

Unlike other types of cancer, there are several options for screening for colorectal cancer (CRC). The most extensively examined method, faecal occult blood testing (FOBT), has been shown, in three large randomized trials, to reduce mortality from CRC by up to 20% if offered biennally and possibly more if offered every year. Recently published data from the US trial suggest that CRC incidence rates are also reduced by up to 20%, but only after 18 years. In this study, the number of positive slides was associated with the positive predictive value both for CRC and adenomas larger than 1 cm, suggesting that the reduction in CRC incidence was caused by the identification and removal of large adenomas. In this respect, this study supports the concept that removing adenomas prevents CRC. More efficient methods of detecting adenomas include the use of colonoscopy or flexible sigmoidoscopy (FS). Considerable evidence exists from case-control and uncontrolled cohort studies to suggest that endoscopic screening by sigmoidoscopy reduces incidence of distal colorectal cancer. However, in the absence of evidence from a randomized trial, several countries have been reluctant to introduce endoscopic screening. Three trialsare currently in progress (in the UK, Italy and the US) to address this issue. Two of these trials are examining the hypothesis that a single FS screen at around age 55-64 might be a cost-effective and acceptable method for reducing CRC incidence rates. Recruitment and screening are now complete in both studies and the first analysis of results on incidence rates is expected in 2004. Colonoscopy screening at 10-year intervals has recently been endorsed in the US on the basis that the reductions in incidence observed with distal CRC screening can be extrapolated to the proximal colon. However, data are lacking and a pilot study for a trial of the acceptability and efficacy of colonoscopy screening is in progress in the US. It has also been suggested that FOBT testing should be used to detect proximal CRC missed by sigmoidoscopy screening, but the small amount of published data suggest that supplementing FS with FOBT offers very little advantage over FS alone. Other forms of CRC screening are under investigation and represent exciting options for the future. Extraction of DNA from stool is now feasible and a number of research groups have shown high sensitivity for CRC using a panel of DNA markers including mutations in k-ras, APC, p53 and BAT26. Data so far indicate that, with the exception of k-ras, these markers are highly specific and therefore represent a significant improvement over FOBT. Whether these tests will replace or supplement existing methods of screening has yet to be determined. It has been suggested that BAT26, which is a marker of microsatellite instability, a feature of proximal sporadic CRC, might be a useful adjunct to sigmoidoscopy screening. Others have suggested that a test for occult blood should be included with the DNA markers to further increase sensitivity. It is not yet known how sensitive these markers are for adenomas--it is only by detecting adenomas that CRC incidence rates can be reduced. A final exciting new option for screening is virtual colonoscopy (VC), which by screening out people without neoplasia allows colonoscopy to be reserved for patients requiring a therapeutic intervention. The sensitivity of VC for large adenomas and CRC appears to be high, although results vary by centre and there is a steep learning curve. Sensitivity for small adenomas is low, but perhaps it is less essential to find such lesions. Some groups have suggested that virtual colonoscopy might be a useful option for investigating patients who test positive with stool-based screening tests. Whichever CRC screening method is finally chosen (and there is no reason why several methods should not ultimately be available), high quality endoscopy resources will always be required to investigate and treat neoplastic lesions detected.

Colorectal cancer screening with CT colonography, colonoscopy, and double-contrast barium enema examination: prospective assessment of patient perceptions and preferences

PURPOSE

To prospectively assess and compare perceptions of and preferences for computed tomographic (CT) colonography, colonoscopy, and double-contrast barium enema examination (DCBE) by asymptomatic patients undergoing colorectal cancer screening.

MATERIALS AND METHODS

A total of 696 asymptomatic patients at higher-than-average risk undergoing colorectal cancer screening were consecutively recruited to undergo both CT colonography and colonoscopy (group 1), and a like group of 617 patients was separately recruited to undergo both CT colonography and DCBE (group 2). Standard bowel preparations were different between the groups undergoing colonoscopy and DCBE. Each patient completed a questionnaire that assessed preparation inconvenience and discomfort, examination discomfort, willingness to repeat examinations, and examination preference. Survey results were compared for significance by using the Wilcoxon rank sum or chi2 test.

RESULTS

The majority of patients considered the preparation to be uncomfortable (group 1, 460 of 515 [89%]; group 2, 482 of 538 [90%]) and inconvenient (group 1, 393 of 502 [78%]; group 2, 427 of 527 [81%]). Reported discomfort was similar at CT colonography and colonoscopy (P =.63) but was less at CT colonography than at DCBE (P <.001). Patients experienced significantly less discomfort than expected at both CT colonography and colonoscopy but not at DCBE. Patients' willingness to undergo frequent rescreening was significantly greater for CT colonography than for either colonoscopy or DCBE. The acceptable time interval between screenings was significantly shorter for all examinations if the bowel preparation could be avoided. Overall, patients preferred CT colonography to colonoscopy (group 1, 72.3% vs 5.1%; P <.001) or to DCBE (group 2, 97.0% vs 0.4%; P <.001).

CONCLUSION

Patients undergoing colorectal cancer screening prefer CT colonography to both colonoscopy and DCBE. The majority of patients experience discomfort and inconvenience with cathartic bowel preparation.

Sensitivity and specificity of a stool DNA multitarget assay panel for the detection of advanced colorectal neoplasia

Colorectal cancer is the second-leading cause of cancer death. New noninvasive options for screening capable of diagnosing cancer at an early stage are needed to improve compliance and reduce mortality. This study was designed to provide an estimate of the sensitivity and specificity of a multitarget assay panel (MTAP) of stool DNA changes. Eighty patients with advanced colorectal neoplasia and 212 control subjects provided stool samples before colonoscopy. Patients with hereditary colorectal cancer syndromes were excluded. The MTAP included 21 specific mutations in the adenomatous polyposis coli (APC), p53, and K-ras genes, a microsatellite instability marker (BAT-26), and a marker of abnormal apoptosis (DNA Integrity Assay). All samples were analyzed in the clinical laboratory at EXACT Sciences. Multitarget assay panel detected 33 of 52 patients (63.5%, 95% confidence interval [CI], 49.0%-76.4%) with invasive colorectal cancer, including 26 of 36 (72.2%) with node-negative disease (American Joint Committee on Cancer [AJCC] stage I/II) and 7 of 16 (43.7%) with advanced disease (AJCC stage III/IV). Sixteen of 28 patients (57.1%; 95% CI, 37.2%-75.5%) with advanced adenomas (lesions containing high-grade dysplasia, villous adenomas, or tubular adenomas > 1 cm in size) were detected, including 6 of 7 (85.7%) with high-grade dysplasia and 10 of 21 (47.6%) with other advanced adenomas. Specificity was 96.2% (95% CI, 92.7%-98.4%) in patients with either no colorectal lesions or diminutive polyps. Multitarget assay panel has better sensitivity than that reported with use of Hemoccult(R) II in fecal occult blood testing, with similar specificity. Sensitivity appeared to be equally high for patients with node-negative and advanced disease, as well as for advanced adenomas. This study contained a disproportionately high number of distal cancers and, as such, may not be representative of results in proximal lesions. Although a prospective study in an average-risk population is needed to validate these findings, MTAP may offer an important noninvasive option for population-based screening.

Current and evolving strategies for colorectal cancer screening

BACKGROUND

Colorectal cancer is a major cause of cancer mortality and morbidity. Screening can potentially prevent most colorectal cancers by detection and removal of precursor adenomas.

METHODS

The literature and clinical practice guidelines are reviewed, with an emphasis on advances of the last 10 years and evolving screening methods.

RESULTS

Colonoscopy has come to be used for screening in persons at average risk for colorectal cancer because of the comparative ineffectiveness of other methods, although these methods continue to be recommended. Virtual colonoscopy and fecal DNA testing are emerging technologies with promise to be more effective than fecal occult blood testing or sigmoidoscopy in selecting those persons who should undergo colonoscopy. Next to age, family history is the most common risk factor for colorectal cancer and one that warrants more aggressive screening and, in some instances, genetic counseling and testing. Hereditary nonpolyposis colorectal cancer accounts for as many as 1 in 20 colorectal cancers, but to take advantage of recent advances in genetic testing for this disorder, a high level of clinical suspicion must be maintained.

CONCLUSIONS

If we are to reduce mortality and morbidity from colorectal cancer, practicing clinicians need to be aware of current and evolving strategies for colorectal screening, and assertively recommend the appropriate strategy to their patients.