Fecal occult blood testing as a screening procedure for colorectal cancer

Evaluation of Organoid-Derived Exosomal microRNA as Liquid Biopsy for Colorectal Cancer: A Multicenter Cross-Sectional Study

Exosomal microRNAs (miRNAs) are candidates for liquid biopsies. Organoid culture systems enable long-term expansion of the colon epithelium. This study evaluated exosomal miRNAs from colorectal cancer organoids for liquid biopsy. Organoids were established from normal colon and colorectal cancer tissues. Exosomes were isolated from conditioned media. miRNAs were extracted from exosomes and compared using microarray analysis. Exosomal miRNAs expression levels in the sera of healthy patients and patients with colorectal cancer were compared at a single institution. The multicenter study was validated using miRNAs upregulated in the serum of colorectal cancer patients, along with exosomal miRNAs reported to be upregulated in colorectal adenoma organoids and sera. A total of 44 exosomal miRNAs were commonly expressed in both normal colorectal epithelial cells and colorectal cancer organoids, whereas 59 were exclusively expressed in colorectal cancer organoids. In a single-center cohort study, two exosomal miRNAs (miR-4284 and miR-5100) were upregulated in the serum of colorectal cancer patients. In a multicenter study, four exosomal miRNAs (miR-4284, miR-5100, miR-1246, and miR-1290) were upregulated in the serum of patients with colorectal cancer. The combination of these four exosomal miRNAs had comparable diagnostic performance to carcinoembryonic antigen, with an area under the curve of 0.75 (95% confidence interval: 0.65-0.83) versus 0.79 (95% confidence interval: 0.70-0.87). Combining the four miRNAs with carcinoembryonic antigen improved diagnostic accuracy, with an area under the curve of 0.82 (95% confidence interval: 0.74-0.89). Exosomal miRNAs derived from colorectal cancer organoids can serve as diagnostic biomarkers for colorectal cancer.

Signature mRNA markers in extracellular vesicles for the accurate diagnosis of colorectal cancer

BACKGROUND

With the increasing incidence of colorectal cancer (CRC), its accurate diagnosis is critical and in high demand. However, conventional methods are not ideal due to invasiveness and low accuracy. Herein, we aimed to identify efficient CRC mRNA markers in a non-invasive manner using CRC-derived extracellular vesicles (EVs). The expression levels of EV mRNAs from cancer cell lines were compared with those of a normal cell line using quantitative polymerase chain reaction. Eight markers were evaluated in plasma EVs from CRC patients and healthy controls. The diagnostic value of each marker, individually or in combination, was then determined using recessive operating characteristics analyses and the Mann-Whitney U test.

RESULTS

Eight mRNA markers (MYC, VEGF, CDX2, CD133, CEA, CK19, EpCAM, and CD24) were found to be more abundant in EVs derived from cancer cell lines compared to control cell lines. A combination of VEGF and CD133 showed the highest sensitivity (100%), specificity (80%), and accuracy (93%) and an area under the curve of 0.96; hence, these markers were deemed to be the CRC signature. Moreover, this signature was found to be highly expressed in CRC-derived EVs compared to healthy controls.

CONCLUSIONS

VEGF and CD133 mRNAs comprise a unique CRC signature in EVs that has the potential to act as a novel, non-invasive, and accurate biomarker that would improve the current diagnostic platform for CRC, while also serving to strengthen the value of EV mRNA as diagnostic markers for myriad of diseases.

Estimating age group-dependent sensitivity and mean sojourn time in colorectal cancer screening

OBJECTIVE

In evaluating the efficacy of cancer screening programmes, sojourn time (duration of the preclinical detectable phase) and sensitivity of the screening test are the two key parameters. Studies suggest that in breast cancer screening, both parameters may vary depending on age at the time of screening, but few studies have examined other cancers. We expanded an existing probability model for periodic screening by performing simultaneous estimation of age group-dependent and sensitivity at preclinical onset time, and tested the expanded model using data from the Korean National Colorectal Cancer Screening Programme.

METHODS

Simulation studies were conducted to assess the performance of the proposed probability model. The method was then applied to the analysis of 376,542 participants aged 50 or over who underwent fecal occult blood testing (FOBT) as part of the National Colorectal Cancer Screening Programme between 2004 and 2007. Age group-dependent mean sojourn time and screening sensitivity of FOBT for colorectal cancer were derived using maximum likelihood estimation.

RESULTS

The method performed well in terms of bias, standard deviation, and coverage probability. National Colorectal Cancer Screening Programme data results indicated that the sensitivity of FOBT to detect colorectal cancer increases with age, while mean sojourn time decreases with age (approximately 4.3 years for participants aged 50-54, 3.9 years at age 55-59, 3.4 years at age 60-64, and 3.6 years at age 65-69, with corresponding sensitivity estimates around 41%, 47%, 45%, and 51%, respectively).

CONCLUSION

Simulation studies showed that the proposed stochastic model considering both mean sojourn time and sensitivity yields highly accurate results.

Understanding of a negative bowel screening result and potential impact on future symptom appraisal and help-seeking behaviour: a focus group study

Background

Colorectal cancer (CRC) screening using a faecal occult blood test (FOBt) has the potential to reduce cancer‐related mortality. Symptom vigilance remains crucial as a proportion of cancers will be diagnosed between screening rounds. A negative FOBt has the potential to influence how participants respond to future symptoms of CRC.

Objective

To explore (i) understanding of a negative FOBt and (ii) the potential impact of a negative FOBt upon future symptom appraisal and help‐seeking behaviour.

Design

Qualitative methodology utilizing focus groups with participants who received a negative FOBt within the National Bowel Cancer Screening Programme in Coventry and Lothian. Topics explored included: experience of screening participation, interpretation and understanding of a negative result, symptom awareness and attitudes towards help‐seeking.

Results

Four broad themes were identified: (i) emotional response to a negative FOBt, (ii) understanding the limitations of FOBt screening, (iii) symptom knowledge and interpretation and (iv) over‐reassurance from a negative FOBt. Participants were reassured by a negative FOBt, but there was variability in the extent to which the result was interpreted as an “all clear”. Some participants acknowledged the residual risk of cancer and the temporal characteristic of the result, while others were surprised that the result was not a guarantee that they did not have cancer.

Discussion and conclusions

Participants recognized that reassurance from a negative FOBt could lead to a short‐term delay in help‐seeking if symptoms developed. Screening programmes should seek to emphasize the importance of the temporal nature of FOBt results with key messages about symptom recognition and prompt help‐seeking behaviour.

Use of the Analysis of the Volatile Faecal Metabolome in Screening for Colorectal Cancer

Diagnosis of colorectal cancer is an invasive and expensive colonoscopy, which is usually carried out after a positive screening test. Unfortunately, existing screening tests lack specificity and sensitivity, hence many unnecessary colonoscopies are performed. Here we report on a potential new screening test for colorectal cancer based on the analysis of volatile organic compounds (VOCs) in the headspace of faecal samples. Faecal samples were obtained from subjects who had a positive faecal occult blood sample (FOBT). Subjects subsequently had colonoscopies performed to classify them into low risk (non-cancer) and high risk (colorectal cancer) groups. Volatile organic compounds were analysed by selected ion flow tube mass spectrometry (SIFT-MS) and then data were analysed using both univariate and multivariate statistical methods. Ions most likely from hydrogen sulphide, dimethyl sulphide and dimethyl disulphide are statistically significantly higher in samples from high risk rather than low risk subjects. Results using multivariate methods show that the test gives a correct classification of 75% with 78% specificity and 72% sensitivity on FOBT positive samples, offering a potentially effective alternative to FOBT.

Upregulation of circulating cancer stem cell marker, DCLK1 but not Lgr5, in chemoradiotherapy-treated colorectal cancer patients

Cancer stem cell (CSC) markers have attracted considerable attention in tumor diagnostic, prognostic, and therapeutic implications. Detection of cancer stem cells in circulating blood using cancer stem cell markers has received remarkable attention recently. In this study, we aimed to investigate the messenger RNA (mRNA) expression level of Lgr5 and DCLK1 as most proposed colorectal CSC markers in blood circulation also determine the subsequent association to patients' clinical and pathological findings. Peripheral blood mononuclear cells (PBMCs) of 58 patients with colorectal cancer at stage I-IV with 33 out of 58 patients undergoing preoperative chemoradiotherapy (CRT), as well as 58 healthy controls have been isolated and the extracted RNAs were analyzed using real-time PCR. The mRNA expression pattern of CSC markers of patients and controls was compared using ΔΔCt method. The expression level of Lgr5 was significantly higher in colorectal cancer (CRC) patients comparing to healthy group (4.8-fold change, p < 0.001). Also there was a significant increase in expression level of Lgr5 in patients at stages III and IV comparing to stages I and II (p = 0.031) and higher grades (p = 0.039) of CRC. The expression of DCLK1 was also elevated in patients significantly (2.7-fold change, p < 0.001) and the related expression was increased by increasing disease stage (p = 0.025). Combination of DCLK1 and Lgr5 markers was analyzed by logistic regression and proved to be a slightly better marker compared to each marker alone. Interestingly the DCLK1 expression level was significantly higher in patients undergoing preoperative CRT (p = 0.041); however, no association to neoadjuvant CRT was observed for Lgr5. Considering the over-expression of DCLK1 and Lgr5 in circulating blood of CRC patients comparing to controls, our results might emphasize on the presence of CSCs in blood of these patients which might be attributed to their clinical and pathological characteristics and may lead to apply in future clinical implications. Moreover, the higher expression level of DCLK1 in patients undergoing CRT can propose it as a more relevant candidate among CSC markers comparing to Lgr5 for CRC patients.

Performance value of high risk factors in colorectal cancer screening in China

AIM: To analyze the performance value of high risk factors in population-based colorectal cancer (CRC) screening in China.

METHODS: We compared the performance value of the immunochemical fecal occult blood test (iFOBT) and other high risk factors questionnaire in a population sample of 13 214 community residents who completed both the iFOBT and questionnaire investigation. Patients with either a positive iFOBT and/or questionnaire were regarded as a high risk population and those eligible were asked to undergo colonoscopy.

RESULTS: The iFOBT had the highest positive predictive value and negative predictive value in screening for advanced neoplasia. The iFOBT had the highest sensitivity, lowest number of extra false positive results associated with the detection of one extra abnormality for screening advanced neoplasias and adenomas. A history of chronic cholecystitis or cholecystectomy, chronic appendicitis or appendectomy, and chronic diarrhea also had a higher sensitivity than a history of adenomatous polyps in screening for advanced neoplasias and adenomas. The sensitivity of a history of chronic cholecystitis or cholecystectomy was highest among the 10 high risk factors in screening for non-adenomatous polyps. A history of chronic appendicitis or appendectomy, chronic constipation, chronic diarrhea, mucous and bloody stool, CRC in first degree relatives, malignant tumor and a positive iFOBT also had higher sensitivities than a history of adenomas polyps in screening for non-adenomatous polyps. Except for a history of malignant tumor in screening for non-adenomatous polyps, the gain in sensitivity was associated with an increase in extra false positive results associated with the detection of one extra abnormality.

CONCLUSION: The iFOBT may be the best marker for screening for advanced neoplasias and adenomas. Some unique high risk factors may play an important role in CRC screening in China.

Review of the evidence for a colorectal cancer screening programme in elderly people

Colorectal cancer is a major public health issue, contributing to 16,000 UK deaths per year, most of these in the elderly population. A new NHS screening programme for colorectal cancer in people over 60 is being introduced across the country throughout 2009. The aim of this research was to review the current literature on colorectal cancer screening and determine how much of the evidence for screening is applicable to elderly people. MEDLINE database was searched for articles published between 1990 and 2007, using search terms of colorectal neoplasms, mass-screening, faecal occult blood, colonoscopy and sigmoidoscopy. Articles for inclusion were limited to those in English and those including older adults. The results showed that evidence for colorectal cancer screening in general has been well researched. However, little was found specifically on screening for elderly people, or looking at the different benefits and limitations in older people compared to younger people. Very few health agencies suggested an upper age limit for screening. In conclusion, there is very little research on screening for colorectal cancer specifically in elderly people, although many health authorities advise such screening. The health needs of an older population are different to those of middle-aged people and at present the screening programmes do not appear to reflect this.

Attitude of the Italian general population towards prevention and screening of the most common tumors, with special emphasis on colorectal malignancies

Screening and early diagnosis of cancer represent relatively recent tools in the long-lasting battle against tumors. If the American public opinion manifests its enthusiasm towards screening, the attitude of European is less well known. The purpose of the present study was to assess the level of knowledge and awareness of cancer screening (with particular emphasis on colorectal neoplasms) among middle-aged individuals. The study group consisted of 945 healthy individuals (489 men, 456 women, average age 57 +/- 12.4 years) who were asked to answer a series of questions about cancer screening and surveillance through a questionnaire presented by trained residents. Each interview lasted 20-30 min. Middle-aged Italians of both sexes seem to be aware of the fact that cancer is a frequent disease; moreover, many of the interviewed subjects believe almost all neoplasms are incurable. Diet, style of life, other environmental factors and familial factors are fully appreciated as relevant risk factors. The exact meaning of prevention was clear to less than half of the subjects. When various cancer sites were analyzed, the existence of preventive measures was well known for breast, cervical and prostate tumors, but their role was less clear for colorectal cancer. Only a fraction of the interviewed individuals were willing to undergo screening; the main reasons for refusal were lack of usefulness and fear of results. Among various tests, ultrasound and endoscopy were usually carried out in the presence of symptoms. Finally, multivariate analysis showed that the two factors significantly associated with the decision to undergo screening procedures were increasing age and level of education. The results of the study suggest that middle-aged Italian individuals, predominantly from Northern regions, have a correct perception of some aspects (frequency, risk factors) of cancer biology, whereas the knowledge of other aspects (outcome, prevention) remains poor or approximate. It follows that one of the main objectives of the Political Class should be to obtain a better education of overage individuals about cancer and the many problems related to this common disease.

Positive rate comparison between immunological and chemical methods of fecal occult blood test in upper digestive tract bleeding

AIM: To compare the positive rates of immune fecal occult blood test (IFOBT) and chemical fecal occult blood test (CFOBT) in screening upper digestive tract bleeding.

METHODS: A total of 206 consecutive patients who suffered upper digestive tract bleeding and underwent endoscopic examination in our hospital were chosen from July 2006 to March 2007. CFOBT (using o-toluidine) and IFOBT were used to detect fecal occult blood positive rate in the same fecal specimen, and comparison was made between the two methods. The positive rates were also analyzed combined with the clinical data.

RESULTS: The results of IFOBT and CFOBT were not associated with anatomic sites in esophageal and gastric cancer, but associated with the invasion depth in gastric cancer, and they were positively correlated with the largest diameter of gastric cancer (IFOBT: r = 0.30, P = 0.02; CFOBT: r = 0.20, P = 0.04). Meanwhile, IFOBT result showed a positive correlation with the largest diameter of esophageal cancer (r = 0.38, P = 0.01). The positive rate of CFOBT was superior to that of squamous cell carcinoma (SCC) antigen detection in esophageal cancer patients (47.43% vs 20.45%, P < 0.05), and the positive rates of both methods were higher than those of CA125, CEA and CA199 detection. CFOBT was superior to IFOBT in detecting gastric cancer, esophageal cancer, reflux esophagitis and peptic ulcer (50.88% vs 35.09%; 47.73% vs 29.55%; 18.00% vs 6.00%; 60.00% vs 41.82%; all P < 0.05). The total positive rate of IFOBT was lower than that of CFOBT in detecting upper digestive tract bleeding.

CONCLUSION: The IFOBT is not suitable for screening upper digestive tract diseases, but relatively specific for lower digestive tract bleeding.

Non-invasive detection of c-myc p64, c-myc p67 and c-erbb-2 in colorectal cancer

OBJECTIVE

Colorectal cancer is a major cause of cancer mortality in the industrialized nations in the West. Because mortality is closely related to the stage of the disease at the time of diagnosis, detection at an early stage is likely to result in improved recovery rates. Since current diagnostic procedures such as colonoscopy are invasive and the fecal occult blood test (FOBT) lacks sensitivity and specificity for the detection of early lesions, the development of non-invasive methods based on molecular markers of neoplasia can lead to earlier diagnosis and more favorable outcomes for patients with colorectal cancer. Recent advances in the technology for isolating colonocytes from stool (SCSR (somatic cell sampling and recovery)) provide a non-invasive tool for the study of biomarkers expressed in colorectal cancer. The aim of this study was to detect mRNA expression of three biomarkers: (c-erbb-2 and two forms of c-myc: p64 and p67) in fecal colonocytes and to evaluate its use in diagnosing colorectal cancer.

MATERIAL AND METHODS

Colonocytes (SCSR cells) were isolated from stools from 30 subjects: 15 colorectal cancer patients and 15 normal controls. One cancer patient was excluded from the final data analysis because the tumor was a gastrointestinal lymphoma. Each sample yielded two fractions: a pellet and an interphase. Expression of c-myc p64, c-myc p67 and c-erbb-2 mRNA was evaluated in each of the fractions by reverse transcriptase-polymerase chain reaction (RT-PCR). A marker was considered positive upon detecting an amplicon of the expected size in agarose gel electrophoresis.

RESULTS

c-myc p64 mRNA expression was observed in both fractions in 78.5% of colorectal cancer patients, compared with 13.3% in the control group (p=0.009). For c-myc p67, 78.6% of the colorectal cancer patients showed mRNA expression in both fractions in comparison with only 13.3% of the controls (p=0.003). C-erbb-2 showed no significant difference in mRNA expression between colorectal cancer and controls. When the data were analyzed for co-expression of c-myc p64 and c-myc p67, in both pellet and interphase, sensitivity was 64% and specificity was 100%.

CONCLUSIONS

Fecal colonocytes isolated by somatic cell sampling and recovery (SCSR) technology could be used for the non-invasive assessment of the expression of biomarkers of colon cancer such as c-myc p64, c-myc p67 and c-erbb-2. The expression of c-myc p64 and c-myc p67 in colonocytes showed a significant association with colorectal cancer and may be helpful as a biomarker for the non-invasive detection of colorectal cancer.

Treatment-related myelodysplastic syndrome/acute myeloid leukemia in survivors of childhood cancer--an update

Treatment-related myelodysplastic syndrome/acute myeloid leukemia (t-MDS/t-AML) is a devastating complication of treatment for childhood cancer. However, the major cause of premature death of children treated for cancer remains their primary cancer. The understanding of the presentation, incidence, predisposing risk factors and pathobiology of t-MDS/t-AML is increasing. This increased understanding has not yet been translated into improved outcomes of therapy for t-MDS/t-AML. However, newer approaches are under study.

MR colonography: baseline appearance of the unprepared rectosigmoid

A retrospective review of 100 routine pelvic MR examinations was conducted to evaluate the appearance of the unprepared rectosigmoid colon, with the aim of informing future strategies for minimal preparation MR colonography. All examinations were reviewed by two observers in consensus, and included matched-location axial T1 weighted and T2 weighted fat suppressed fast spin echo (FSFSE) images. Analysis revealed that the overall appearance of the faecal material in the colon could simulate tumour in 80% of T1 weighted and 17% of T2 weighted images. By matching the images from the two sequences for each patient the faeces had an overall appearance that would mimic tumour in only 7% of cases. However, luminal tumour-mimicking foci of signal occurred frequently, present in 91% of T1 weighted and 85% of T2 weighted studies. The results indicate that if bowel-cleansing regimens are to be avoided for MR colonography, effective strategies such as dietary restriction and use of oral contrast agents will be required to reduce luminal signal on T2 weighting and eliminate polyp-mimicking foci. The results also suggest that T2 weighted strategies should be further investigated and that combination with T1 weighted imaging may improve discrimination of lesions from normal faecal material.