Seasonal variations do not affect the superiority of fecal immunochemical tests over guaiac tests for colorectal cancer screening

The aim of this study was to compare the seasonal variation in performance of a faecal immunochemical test for haemoglobin (FIT) and a guaiac test (gFOBT) for colorectal cancer screening. From June 2009 to May 2011, 18,290 screening participants (50–74 years old) performed OC‐SENSOR quantitative FIT (1 sample) and Hemoccult II gFOBT (3 stool samples with 2 spots/sample). Referral for colonoscopy required a minimum of one positive spot (gFOBT), or a positive FIT [cut‐off 150 ng haemoglobin/mL buffer (i.e. 30 μg haemoglobin/g feces)]. The performance of tests for detection of advanced neoplasia was compared according to seasons using Receiver Operating Characteristics (ROC) curves, at various FIT cut‐off values. The positivity rate of FIT was significantly lower in the summer compared with other seasons (2.3% versus 3.0%, p = 0.03), whilst the positivity rate of gFOBT increased in the autumn (1.8% versus 1.5%, p = 0.11). FIT was clinically more effective than gFOBT over the four season‐specific ROC curves. At the cut‐off concentration used in the study, the season‐specific FIT/gFOBT ratios for true positive rates were: 2.8 (Autumn), 2.5 (Winter), 3.0 (Spring), 3.7 (Summer), and for false positive rates: 1.2 (Autumn), 1.5 (Winter), 1.8 (Spring), 0.9 (Summer). Therefore, in this study with this cut‐off concentration and in spite of lower positivity rate in summer, the seasonal variations of performance of OC‐SENSOR FIT led to improved gain in specificity in the summer, without a decrease in gain in sensitivity compared with gFOBT.     

Screening for colorectal neoplasias with fecal occult blood tests: false-positive impact of non-dietary restriction

Objective: Screening for colorectal cancer using guaiac-based fecal occult blood tests (gFOBT) is wellestablished in Western populations, but is hampered by poor patient compliance due to the imposed dietaryrestrictions. Fecal immunochemical tests (FIT) do not require dietary restriction, but are more expensive thangFOBT and therefore restrict its use in developing countries in Asia. However, Asian diets being low in meatcontent may not require diet restriction for gFOBT to achieve equivalent results. The objective of this study wasto evaluate and compare the validity and suitability of gFOBT and FIT or a combination of the two in screeningfor colorectal neoplasias without prior dietary restriction in an Asian population. Methods: Patients referred tothe Endoscopic Unit for colonoscopy were recruited for the study. Stool samples were collected prior to bowelpreparation, and tested for occult blood with both gFOBT and FIT. Dietary restriction was not imposed. Toassess the validity of either tests or in combination to detect a neoplasm or cancer in the colon, their false positiverates, their sensitivity (true positive rate) and the specificity (true negative rate) were analyzed and compared.Results: One hundred and three patients were analysed. The sensitivity for picking up any neoplasia was 53%for FIT, 40% for gFOBT and 23.3% for the combination. The sensitivities for picking up only carcinoma were77.8% , 66.7% and 55.5%, respectively. The specificity for excluding any neoplasia was 91.7% for FIT, 74% forgFOBT and 94.5% for a combination, whereas for excluding only carcinomas they were 84%, 73.4% and 93.6%.Of the 69 with normal colonoscopic findings, FOBT was positive in 4.3%, 23.2 %and 2.9% for FIT, gFOBT, orcombination of tests respectively. Conclusion: FIT is the recommended method if we are to dispense with dietaryrestriction in our patients because of its relatively low-false positivity and better sensitivity and specificity rates.     

Strong subsite‐specific variation in detecting advanced adenomas by fecal immunochemical testing for hemoglobin

Fecal immunochemical tests (FITs) for hemoglobin are increasingly recommended and used in colorectal cancer (CRC) screening. We aimed to provide a detailed assessment of the sensitivity of FIT according to type and subsite of neoplasms in a true screening setting. A quantitative FIT (FOB Gold, Sentinel Diagnostics, Milano, Italy) was applied prior to colonoscopy by 3,466 participants of the German screening colonoscopy program. Subsite specific sensitivity for various types of colorectal neoplasms was derived by comparing FIT results with findings at screening colonoscopy. The most advanced finding at colonoscopy was CRC, advanced adenoma, and nonadvanced adenoma in 29, 354 and 686 cases, respectively. Per‐adenoma sensitivity for large advanced adenomas (>1 cm) strongly varied by location (p < 0.001): cecum: 0/14 (0%), ascending colon and right flexure: 11/43 (26%), transverse colon and left flexure: 2/14 (14%), descending colon: 7/12 (58%), sigmoid colon: 47/92 (51%), rectum: 14/39 (36%). By contrast, the FIT detected all of 5 proximal CRC and 23 out of 24 (96%) distal CRCs, whereas per‐adenoma sensitivity of both proximal (17/259, 7%) and distal nonadvanced adenomas (20/237, 8%) essentially equaled the false positivity rate among those without neoplasms (152/2,397, 6%). In conclusion, we found a very large gradient of subsite specific FIT sensitivity for detecting large advanced adenomas ranging from 0% for advanced adenomas located in the cecum to >50% for those located in the descending or sigmoid colon. By contrast, FIT sensitivity was uniformly excellent for CRC and uniformly poor for nonadvanced adenomas, regardless of their location.     

Use of faecal markers in screening for colorectal neoplasia: a European group on tumor markers position paper

Several randomized controlled trials have shown that population‐based screening using faecal occult blood testing (FOBT) can reduce mortality from colorectal neoplasia. Based on this evidence, a number of countries have introduced screening for colorectal cancer (CRC) and high‐risk adenoma and many others are considering its introduction. The aim of this article is to critically review the current status of faecal markers as population‐based screening tests for these neoplasia. Most of the available faecal tests involve the measurement of either occult blood or a panel of DNA markers. Occult blood may be measured using either the guaiac faecal occult blood test (gFOBT) or a faecal immunochemical test (iFOBT). Although iFOBT may require a greater initial investment, they have several advantages over gFOBT, including greater analytical sensitivity and specificity. Their use results in improved clinical performance and higher uptake rates. Importantly for population screening, some of the iFOBTs can be automated and provide an adjustable cutoff for faecal haemoglobin concentration. However, samples for iFOBT, may be less stable after collection than for gFOBT. For new centres undertaking FOBT for colorectal neoplasia, the European Group on Tumour Markers recommends use of a quantitative iFOBT with an adjustable cutoff point and high throughput analysis. All participants with positive FOBT results should be offered colonoscopy. The panel recommends further research into increasing the stability of iFOBT and the development of improved and affordable DNA and proteomic‐based tests, which reduce current false negative rates, simplify sample transport and enable automated analysis.     

Screening for colorectal cancer: Comparison of perceived test burden of guaiac-based faecal occult blood test,faecal immunochemical test and flexible sigmoidoscopy

BackgroundPerceived burden of colorectal cancer (CRC) screening is an important determinant of participation in subsequent screening rounds and therefore crucial for the effectiveness of a screening programme. This study determined differences in perceived burden and willingness to return for a second screening round among participants of a randomised population-based trial comparing a guaiac-based faecal occult blood test (gFOBT), a faecal immunochemical test (FIT) and flexible sigmoidoscopy (FS) screening.MethodsA representative sample of the Dutch population (aged 50–74 years) was randomised to be invited for gFOBT, FIT and FS screening. A random sample of participants of each group was asked to complete a questionnaire about test burden and willingness to return for CRC screening.ResultsIn total 402/481 (84%) gFOBT, 530/659 (80%) FIT and 852/1124 (76%) FS screenees returned the questionnaire. The test was reported as burdensome by 2.5% of gFOBT, 1.4% of FIT and 12.9% of FS screenees (comparing gFOBT versus FIT p = 0.05; versus FS p < 0.001). In total 94.1% of gFOBT, 94.0% of FIT and 83.8% of FS screenees were willing to attend successive screening rounds (comparing gFOBT versus FIT p = 0.84; versus FS p < 0.001). Women reported more burden during FS screening than men (18.2% versus 7.7%; p < 0.001).ConclusionsFIT slightly outperforms gFOBT with a lower level of reported discomfort and overall burden. Both FOBTs are better accepted than FS screening. All three tests have a high level of acceptance, which may affect uptake of subsequent screening rounds and should be taken into consideration before implementing a CRC screening programme.     

Screening for colorectal cancer: random comparison of guaiac and immunochemical faecal occult blood testing at different cut-off levels

Immunochemical faecal occult blood testing (FIT) provides quantitative test results, which allows optimisation of the cut-off value for follow-up colonoscopy. We conducted a randomised population-based trial to determine test characteristics of FIT (OC-Sensor micro, Eiken, Japan) screening at different cut-off levels and compare these with guaiac-based faecal occult blood test (gFOBT) screening in an average risk population. A representative sample of the Dutch population (n=10 011), aged 50–74 years, was 1 : 1 randomised before invitation to gFOBT and FIT screening. Colonoscopy was offered to screenees with a positive gFOBT or FIT (cut-off 50 ng haemoglobin/ml). When varying the cut-off level between 50 and 200 ng ml⁻¹, the positivity rate of FIT ranged between 8.1% (95% CI: 7.2–9.1%) and 3.5% (95% CI: 2.9–4.2%), the detection rate of advanced neoplasia ranged between 3.2% (95% CI: 2.6–3.9%) and 2.1% (95% CI: 1.6–2.6%), and the specificity ranged between 95.5% (95% CI: 94.5–96.3%) and 98.8% (95% CI: 98.4–99.0%). At a cut-off value of 75 ng ml⁻¹, the detection rate was two times higher than with gFOBT screening (gFOBT: 1.2%; FIT: 2.5%; P<0.001), whereas the number needed to scope (NNscope) to find one screenee with advanced neoplasia was similar (2.2 vs 1.9; P=0.69). Immunochemical faecal occult blood testing is considerably more effective than gFOBT screening within the range of tested cut-off values. From our experience, a cut-off value of 75 ng ml⁻¹ provided an adequate positivity rate and an acceptable trade-off between detection rate and NNscope.     

Impact of time between faecal immunochemical tests in colorectal cancer screening on screening results: A natural experiment

Repeated rounds of faecal immunochemical testing (FIT) for occult blood is a common method for screening for colorectal cancer (CRC). However, the time interval between FIT rounds is not thoroughly investigated. In a CRC screening trial in South-Eastern Norway, individuals were invited for biennial FIT between 2012 and 2019. The positivity threshold was >15 mcg haemoglobin/g faeces (mcg/g). Due to organizational challenges, the interval between screening rounds randomly varied between 1.5 and 3.5 years, forming a natural experiment. We investigated the detection rate of CRC and advanced neoplasia (AN: CRC or advanced adenoma) at the subsequent round (FIT₂), according to the faecal haemoglobin concentration (f-Hb) at the initial screening round (FIT₁), and time between the two screening rounds. 18 522 individuals with negative FIT₁ who attended FIT₂ were included in this study. 245 AN were detected at FIT₂, of which 34 were CRC. The CRC detection rate at FIT₂ for participants with FIT₁ = 0 mcg/g was 0.09% while it was 0.28% for participant with 0 > FIT₁ ≤ 15 mcg/g; odds ratio (OR) 3.22, 95% CI 1.49-6.95. For each 3 months' increment between FITs, the OR for detecting CRC was 1.33 (95% CI 0.98-1.79), while the OR was 1.13 (1.02-1.26) for AN. Individuals with FIT₁-value of 0 mcg/g, had a lower AN detection rate compared with participants with 0 > FIT₁ ≤ 15 mcg/g, irrespective of time between tests. Although CRC and AN detection rates increase with increasing time interval between FITs, individuals with undetectable f-Hb at first screen have substantially lower risk of CRC at the next screening round compared with individuals with detectable f-Hb.     

Cost-effectiveness of population-based screening for colorectal cancer: a comparison of guaiac-based faecal occult blood testing, faecal immunochemical testing and flexible sigmoidoscopy

Background:

Several colorectal cancer-screening tests are available, but it is uncertain which provides the best balance of risks and benefits within a screening programme. We evaluated cost-effectiveness of a population-based screening programme in Ireland based on (i) biennial guaiac-based faecal occult blood testing (gFOBT) at ages 55–74, with reflex faecal immunochemical testing (FIT); (ii) biennial FIT at ages 55–74; and (iii) once-only flexible sigmoidoscopy (FSIG) at age 60.

Methods:

A state-transition model was used to estimate costs and outcomes for each screening scenario vs no screening. A third party payer perspective was adopted. Probabilistic sensitivity analyses were undertaken.

Results:

All scenarios would be considered highly cost-effective compared with no screening. The lowest incremental cost-effectiveness ratio (ICER vs no screening €589 per quality-adjusted life-year (QALY) gained) was found for FSIG, followed by FIT (€1696) and gFOBT (€4428); gFOBT was dominated. Compared with FSIG, FIT was associated with greater gains in QALYs and reductions in lifetime cancer incidence and mortality, but was more costly, required considerably more colonoscopies and resulted in more complications. Results were robust to variations in parameter estimates.

Conclusion:

Population-based screening based on FIT is expected to result in greater health gains than a policy of gFOBT (with reflex FIT) or once-only FSIG, but would require significantly more colonoscopy resources and result in more individuals experiencing adverse effects. Weighing these advantages and disadvantages presents a considerable challenge to policy makers.     

Performance of a colorectal cancer screening protocol in an economically and medically underserved population

The performance of combining fecal immunochemical tests (FITs) and a high-risk factor questionnaire (HRFQ) in colorectal cancer (CRC) screening in economically and medically underserved populations is uncertain. This study investigated the performance of a CRC screening protocol of combining FITs and an HRFQ as primary screening methods in a rural Chinese population. A CRC mass screening was conducted using FITs and an HRFQ as the first and colonoscopy as the second stage of screening in Jiashan, 2007-2009. The target population was 31,963 residents in three communities. The compliance was 84.7% for HRFQ, 76.4% for FITs, and 78.7% for colonoscopy. The detected rates of cancer, adenoma, nonadenomatous polyps, and advanced neoplasm were 2.7%, 14.8%, 5.9%, and 8.9% by FITs, which were higher than those by HRFQ (0.5%, 9.2%, 4.8%, and 3.8%, respectively). There was no significant difference in detected rate for nonadenomatous polyps between FITs and HRFQ. A total of 41.2% adenomas, 53.2% nonadenomatous polyps, and 29.8% advanced neoplasms were detected by HRFQ but missed by FITs. Positive predictive value of the screening protocol of combining FITs and HRFQ for advanced neoplasm was 5.7%, which was higher than FITs alone. Men had a higher prevalence of advanced neoplasm than women. Results indicate that combining FITs and HRFQ as primary screening methods is an efficient CRC screening strategy in economically and medically underserved populations.     

Men with negative results of guaiac‐based fecal occult blood test have higher prevalences of colorectal neoplasms than women with positive results

Guaiac‐based fecal occult blood tests (gFOBTs) are the most commonly applied tests for colorectal cancer screening globally but have relatively poor sensitivity to detect colorectal neoplasms. Men have higher prevalences of colorectal neoplasms than women. In case of a positive gFOBT result, participants are referred to colonoscopy, independent of sex. To assess performance of gFOBT in routine screening practice, we assessed age and sex specific prevalences (age groups: 55–59, 60–64, 65–69 and 70–74) of colorectal neoplasms in 182,956 women and men undergoing colonoscopy for primary screening and in 20,884 women and men undergoing colonoscopy to follow‐up a positive gFOBT in Bavaria, Germany, in 2007–2009. We conducted model calculations to estimate prevalences among gFOBT negative individuals. Analogous model calculations were performed for women and men tested positive or negative with fecal immunochemical tests. In all age groups (55–59, 60–64, 65–69 and 70–74 years), men undergoing colonoscopy for primary screening had substantially higher prevalences of any colorectal neoplasms and essentially the same prevalences of advanced colorectal neoplasms compared to women undergoing colonoscopy to follow‐up a positive gFOBT. Model calculations suggest that men with negative gFOBT likewise have substantially higher prevalences of colorectal neoplasms than gFOBT positive women in each age group. Model calculations further indicate that no such sex paradoxon occurs, and a much clearer risk stratification can be achieved with fecal immunochemical tests. Our findings underline need to move forward from and overcome shortcomings of gFOBT‐based colorectal cancer screening.     

Factors associated with false-positive fecal immunochemical tests in a large German colorectal cancer screening study

In recent years fecal immunochemical tests (FITs) have been offered as a primary screening test for colorectal cancer (CRC) in a growing number of countries. Our study aims to identify factors associated with apparently false-positive results of FITs. In this cross-sectional study within the German population-based screening colonoscopy program, participants were invited to provide a stool sample for FIT prior to colonoscopy. Four thousand six hundred and fifty six participants aged 50–79 years with no known history of CRC or inflammatory bowel disease (IBD) and no findings of neoplasms at screening colonoscopy were included in the current analyses. Main outcome measures were rates and factors associated with apparently false-positive FIT results. Apparently false-positive FIT results were found for 378 participants (8.1%). Male sex (OR = 1.30, 95%CI 1.03, 1.62), age ≥65 years (OR = 1.27, 95%CI 1.01, 1.59), a BMI ≥30 kg/m² (OR = 1.81, 95%CI 1.36, 2.40), current smoking (OR = 1.63, 95%CI 1.18, 2.25), use of aspirin (OR = 1.36, 95%CI 1.02, 1.82) and a new diagnosis of IBD (OR = 9.13, 95%CI 2.18, 38.19) or other non-neoplastic findings (OR = 1.86, 95%CI 1.37, 2.51) at screening colonoscopy were independently associated with significantly increased odds of a positive FIT. Although considered false positive in the context of CRC screening, the identified factors associated with apparently false-positive FIT results are known risk factors for and may point to conditions other than colorectal neoplasms that may be potential sources of gastrointestinal bleeding, potentially requiring further medical follow up.     

Significant decrease in interval colorectal cancer incidence after implementing immunochemical testing in a multiple-round guaiac-based screening programme

Background and aims We aimed to evaluate the effects of switching to faecal immunochemical testing (FIT) on the cumulative 2-year incidence rate of interval cancers, interval cancer rate and test sensitivity within a mature population-based colorectal cancer screening programme consisting of six rounds of biennial guaiac faecal occult blood testing (gFOBT).Methods The FIT results were compared with those of gFOBT used in each of the previous two rounds. For the three rounds analysed, 279,041 tests were performed by 156,186 individuals. Logistic regression analysis was used to determine interval cancer risk factors (Poisson regression) and to compare the sensitivity of FIT to gFOBT.Results There were 612 cases of screen-detected cancers and 209 cases of interval cancers. The sex- and age-adjusted cumulative 2-year incidence rates of interval cancers were 55.7 (95% CI, 45.3–68.5), 42.4 (95% CI, 32.6–55.2) and 15.8 (95% CI, 10.9–22.8) per 100,000 person-years after the last two rounds of gFOBT and FIT, respectively. The FIT/gFOBT incidence rate ratio was 0.38 [95% CI, 0.27–0.54] (P < 0.001). Sex- and age-adjusted sensitivity was significantly higher with FIT than with gFOBT (OR = 6.70 [95% CI, 4.48–10.01], P < 0.0001).Conclusions This population-based study revealed a dramatic decrease in the cumulative incidence rates of interval cancers after switching from gFOBT to FIT. These data provide an additional incentive for countries still using gFOBT to switch to FIT.Subject terms: Cancer screening, Colorectal cancer     

Association of FOBT-assessed faecal Hb content with colonic lesions detected in the Florence screening programme

We assessed the correlation between quantitative results of immunological faecal occult blood testing (I-FOBT) and colonic lesions (191 colorectal cancers, 890 adenomas) detected at colonoscopy in 2597 FOBT+ (cutoff 100 ng ml(-1) Hb) subjects. At univariate analysis, a higher average faecal Hb content was significantly associated with male gender (P=0.003), age (P=0.02), and colonoscopy findings (P=0.000). Among adenomas, higher faecal Hb content was significantly associated with size (P=0.0000), presence of severe dysplasia (P=0.0001), presence of villous component (P=0.0002), and location in the left colon (P=0.003). At multivariate analysis adjusting for potential confounders, age (P=0.03), size (P=0.0000), and location in the left colon (P=0.0005) were confirmed as having an independent association with higher faecal Hb content. Immunological FOBT is confirmed to be a specific screening test to detect cancer and adenoma, with a low positivity rate (3.7%) and a high positive predictive value (41.5%). Faecal Hb content is significantly higher for those lesions (cancer and high-risk adenomas) screening is aimed at detecting.     

Impact of adenoma detection on the benefit of faecal testing vs. colonoscopy for colorectal cancer

Colonoscopy quality, as measured by adenoma detection rates, varies widely across providers and is inversely related to patients' post‐colonoscopy cancer risk. This has unknown consequences for the benefits of faecal immunochemical testing (FIT) vs. primary colonoscopy screening for colorectal cancer. Using an established microsimulation model, we predicted the lifetime colorectal cancer incidence and mortality benefits of annual FIT vs. 10‐yearly colonoscopy screening at differing ADR levels (quintiles; averages 15.3–38.7%), with colonoscopy performance assumptions estimated from community‐based data on physician ADRs and patients' post‐colonoscopy risk of cancer. For patients receiving FIT screening with follow‐up colonoscopy by physicians from the highest ADR quintile, simulated lifetime cancer incidence and mortality were 28.8 and 5.4 per 1,000, respectively, vs. 20.6 and 4.4 for primary colonoscopy screening (risk ratios, RR = 1.40; 95% probability interval (PI), 1.19–1.71 for incidence, and RR = 1.22; 95%PI, 1.02–1.54 for mortality). With every 5% point ADR decrease, lifetime cancer incidence was predicted to increase on average 9.0% for FIT vs. 12.3% for colonoscopy, and mortality increased 9.9% vs. 13.3%. In ADR quintile 1, simulated mortality was lower for FIT than colonoscopy screening (10.1 vs. 11.8; RR = 0.85; 95%PI, 0.83–0.90), while incidences were more similar. This suggests that relative cancer incidence and mortality reductions for FIT vs. colonoscopy screening may differ by ADR, with fewer predicted deaths with colonoscopy screening in higher ADR settings and fewer deaths with annual FIT screening in lower ADR settings.     

Osteopontin is a useful predictor of bone metastasis and survival in patients with locally advanced nasopharyngeal carcinoma

Guaiac‐based fecal occult blood tests (gFOBTs) are the most widely used noninvasive tests for colorectal cancer screening. While it is well known that they detect only a minority of colorectal adenomas, evidence for the characteristics of adenomas associated with detection is sparse. We derived estimates of the positive likelihood ratio (LR+), a summary measure of diagnostic performance, according to adenoma characteristics by comparing findings at colonoscopy among 19,208 and 181,128 participants who underwent colonoscopy to follow‐up a positive gFOBT and as a primary screening examination, respectively, in Bavaria, Germany, in 2007–2009. Age and sex‐adjusted estimates of LR+ (95% confidence intervals, 95% CI) ranged from 1.09 (1.05–1.13) for adenomas <1 cm to 2.52 (2.30–2.75) for adenomas >2 cm, and were much higher for pedunculated adenomas (1.96, 95% CI 1.85–2.08) than for flat or sessile adenomas (1.11, 95% CI 1.02–1.21 and 1.12, 95% CI 1.08–1.16, respectively). Villous or tubulovillous structure and dysplasia were likewise associated with a higher chance to be detected by gFOBT. Diagnostic performance was worse for proximal than for distal adenomas (age and sex adjusted LR+:1.16, 95% CI 1.09–1.23 and 1.35, 95% CI 1.29–1.41, respectively) which was explained by the lower proportions of large, pedunculated and nontubular adenomas in the proximal colon. Size, pedunculated shape, and nontubular histology are the key determinants of detection which also explain lower detection rates of adenomas located in the proximal colon.     

2015—2019年广州市结直肠癌筛查不同初筛方式阳性人群肠镜结果分析

[目的]分析2015—2019年广东省广州市结直肠癌筛查的数据,比较不同初筛方式阳性人群肠镜结果,以期更好地动员居民参与肠镜检查。[方法]整理2015—2019年广州市结直肠癌筛查数据,将初筛阳性人群分为5组:仅高危因素问卷评估阳性(免疫化学法粪便隐血试验阴性)[high risk factor questionnaire (HRFQ) positive and fecal immunochemical test(FIT)negative,HRFQ+&Double-FIT-]、HRFQ阳性和1次FIT阳性(HRFQ+&Single-FIT+)、HRFQ阴性和1次FIT阳性(HRFQ-&Single-FIT+)、HRFQ阴性和2次FIT阳性(HRFQ-&DoubleFIT+)、HRFQ阳性和2次FIT阳性(HRFQ+&Double-FIT+)。采用多元Logistic回归比较不同初筛方式阳性人群肠镜结果。[结果]广州市共完成初筛403 585人,初筛阳性69 619人,初筛阳性率为17.25%,肠镜检查依从性为28.53%;HRFQ+&Double-FIT+、HRFQ-&DoubleFIT+、HRFQ-&Single-FIT+、HRFQ+&Single-FIT+组检出异常风险分别是HRFQ+&DoubleFIT-组的1.638、1.642、1.174和1.515倍,HRFQ-&Double-FIT+和HRFQ+&Single-FIT+组检出腺瘤风险分别是HRFQ+&Double-FIT-组的1.306和1.214倍,HRFQ+&Double-FIT+、HRFQ-&Double-FIT+、HRFQ-&Single-FIT+、HRFQ+&Single-FIT+检出进展性腺瘤风险分别是HRFQ+&Double-FIT-组的4.823、5.870、2.571和2.463倍,HRFQ+&Double-FIT+、HRFQ-&Double-FIT+、HRFQ-&Single-FIT+、HRFQ+&Single-FIT+检出肠癌风险分别是HRFQ+&Double-FIT-组的33.532、31.345、5.353和6.627倍。[结论]广州市结直肠癌筛查肠镜检查依从性较低,应加大对结直肠癌初筛阳性人群的动员,尤其是FIT 2次阳性的人群。     

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.     

Test performance of immunologic fecal occult blood testing and sigmoidoscopy compared with primary colonoscopy screening for colorectal advanced adenomas

Given the current increase in colorectal cancer screening, information on performance of screening tests is needed, especially in groups with a presumed lower test performance. We compared test performance of immunologic fecal occult blood testing (FIT) and pseudosigmoidoscopy with colonoscopy for detection of advanced adenomas in an average risk screening population. In addition, we explored the influence of gender, age, and location on test performance. FIT was collected prior to colonoscopy with a 50 ng/mL cutoff point. FIT results and complete colonoscopy findings were available from 329 subjects (mean age: 54.6 ± 3.7 years, 58.4% women). Advanced adenomas were detected in 38 (11.6%) of 329 subjects. Sensitivity for advanced adenomas of FIT and sigmoidoscopy were 15.8% (95% CI: 6.0-31.3) and 73.7% (95% CI: 56.9-86.6), respectively. No sensitivity improvement was obtained using the combination of sigmoidoscopy and FIT. Mean fecal hemoglobin in FIT positives was significantly lower for participants with only proximal adenomas versus those with distal ones (P = 0.008), for women versus men (P = 0.023), and for younger (<55 years) versus older (≥55 years) subjects (P = 0.029). Sensitivities of FIT were 0.0% (95% CI: 0.0-30.9) in subjects with only proximal versus 21.4% (95% CI: 8.3-41.0) in those with distal nonadvanced adenomas; 5.3% (95% CI: 0.0-26.0) in women versus 26.3% (95% CI: 9.2-51.2) in men; 9.5% (95% CI: 1.2-30.4) in younger versus 23.5% (95% CI: 6.8-49.9) in older subjects. Sigmoidoscopy had a significantly higher sensitivity for advanced adenomas than FIT. A single FIT showed very low sensitivity, especially in subjects with only proximal nonadvanced adenomas, in women, and in younger subjects. This points to the existence of "low" FIT performance in subgroups and the need for more tailored screening strategies.     

Quantitative fecal immunochemical tests for colorectal cancer screening

Fecal immunochemical tests (FITs) for hemoglobin (Hb) are increasingly used for colorectal cancer (CRC) screening. We aimed to review, summarize and compare reported diagnostic performance of various FITs. PubMed and Web of Science were searched from inception to July 24, 2017. Data on diagnostic performance of quantitative FITs, conducted in colonoscopy‐controlled average‐risk screening populations, were extracted. Summary receiver operating characteristic (ROC) curves were plotted and correlations between thresholds, positivity rates (PRs), sensitivities and specificities were assessed. Seven test brands were investigated across 22 studies. Although reported sensitivities for CRC, advanced adenoma (AA) and any advanced neoplasm (AN) varied widely (ranges: 25–100%, 6–44% and 9–60%, respectively), with specificities for AN ranging from 82% to 99%, the estimates were very close to the respective summary ROC curves whose areas under the curve (95% CI) were 0.905 (0.88–0.94), 0.683 (0.67–0.70) and 0.710 (0.70–0.72) for CRC, AA and AN, respectively. The seemingly large heterogeneity essentially reflected variations in test thresholds (range: 2–82 µg Hb/g feces) and showed moderate correlations with sensitivity (r = ?0.49) and specificity (r = 0.60) for AN. By contrast, observed PRs (range: 1–21%) almost perfectly correlated with sensitivity (r = 0.84) and specificity (r = ?0.94) for AN. The apparent large heterogeneity in diagnostic performance between various FITs can be almost completely overcome by appropriate threshold adjustments. Instead of simply applying the threshold recommended by the manufacturer, screening programs should adjust the threshold to yield a desired PR which is a very good proxy indicator for the specificity and the subsequent colonoscopy workload.     

Use of Fecal Immunochemical Tests in the Iowa Research Network

Although the fecal immunochemical test (FIT) has recently emerged as an effective and affordable colorectal cancer screening option, many family physician offices continue to use guaiac-based tests. The purpose of this study was to assess the use of FITs in the Iowa Research Network and to assess physicians' knowledge about FITs. A cover letter and questionnaire were faxed twice to the 291 physician members followed up by a mailing. One hundred and seven (37 %) questionnaires were returned. Participants' mean age was 55 years with 78 male responders. Fifty-two (49 %) of the physician's offices were in a nonmetro area. Fifty-one (49 %) reported using guaiac-based tests and 39 (39 %) reported using FITs. Many physicians were unsure of the answers for the FIT knowledge questions. FIT use is not widespread in Iowa Research Network physician offices, and not all physicians are aware of the type of fecal occult blood test being conducted in their office.