Trends in quality of screening colonoscopy in Austria.

Background and study aim: Screening colonoscopy only effectively prevents colorectal cancer if performed with high quality. The aim of this study was to analyze the detection rates of premalignant colorectal lesions in screening colonoscopies performed within a nationwide quality control program for screening colonoscopy in Austria. Methods: Data from electronic records of the screening program from its implementation in 2007 until December 2014 were analyzed in order to calculate detection rates for adenomas, advanced adenomas, polyps, and proximal lesions, and rates of cecal intubation, sedation, complications, and adequate bowel preparation. Results were evaluated to identify trends and changes in quality parameters over the 8-year study period. Results: During the study period, 301 endoscopists provided data from 159 246 screening colonoscopies. Mean age of screened individuals was 61.1 years, and 49.1 % were women. Significant increases over time were found for age- and sex-adjusted adenoma detection rates (ADRs), which increased from a mean of 22.2 % (SD 10.7 %) in 2007/2008 to 24.2 % (SD 11.6 %) in 2013/2014. On average, each endoscopist increased their individual ADR by + 1.5 percentage points per 2-year period (95 % confidence interval [CI] 0.9 - 2.2 percentage points; P < 0.01). Similarly, detection rates for proximal lesions rose from 15.8 % (SD 9.8 %) to 21.7 % (SD 13.3 %  + 2.5 percentage points per 2-year period, 95 %CI 1.9 - 3.1 percentage points; P < 0.01). ADR in men increased from 27.6 % in 2007/2008 (SD 11.1 %) to 29.2 % in 2013/2014 (SD 12.7 %; P < 0.01); ADR in women increased from 14.2 % (SD 7.1 %) in 2007/2008 to 19.0 % (SD 10.5 %) in 2013/2014 (P < 0.01). Advanced adenoma detection rates decreased during the study period, from 11.4 % (SD 9.0 %) in 2007/2008 to 7.6 % (SD 5.4 %) in 2013/2014 (P = 0.06) in men, and from 5.5 % (SD 5.3 %) in 2007/2008 to 4.0 % (SD 4.1 %) in 2013/2014 in women (P = 0.21). Conclusions: This study showed an improvement in the quality of screening colonoscopies performed within a quality assurance program in Austria between 2007 and 2014. Although, overall ADR increased significantly during the study period, there was a decrease in the rate of advanced adenoma detection.

Randomized, multicenter study: on-demand versus continuous maintenance treatment with esomeprazole in patients with non-erosive gastroesophageal reflux disease.

BACKGROUND: Most patients with gastroesophageal reflux disease experience symptomatic relapse after stopping acid-suppressive medication. The aim of this study was to compare willingness to continue treatment with esomeprazole on-demand versus continuous maintenance therapy for symptom control in patients with non-erosive reflux disease (NERD) after 6 months. METHODS: This multicenter, open-label, randomized, parallel-group study enrolled adults with NERD who were heartburn-free after 4 weeks' treatment with esomeprazole 20 mg daily. Patients received esomeprazole 20 mg daily continuously or on-demand for 6 months. The primary variable was discontinuation due to unsatisfactory treatment. On-demand treatment was considered non-inferior if the upper limit of the one-sided 95 % confidence interval (CI) for the difference between treatments was <10 %. RESULTS: Of 877 patients enrolled, 598 were randomized to maintenance treatment (continuous: n = 297; on-demand: n = 301). Discontinuation due to unsatisfactory treatment was 6.3 % for on-demand and 9.8 % for continuous treatment (difference -3.5 % [90 % CI: -7.1 %, 0.2 %]). In total, 82.1 and 86.2 % of patients taking on-demand and continuous therapy, respectively, were satisfied with the treatment of heartburn and regurgitation symptoms, a secondary variable (P = NS). Mean study drug consumption was 0.41 and 0.91 tablets/day, respectively. Overall, 5 % of the on-demand group developed reflux esophagitis versus none in the continuous group (P < 0.0001). The Gastrointestinal Symptom Rating Scale Reflux dimension was also improved for continuous versus on-demand treatment. Esomeprazole was well tolerated. CONCLUSIONS: In terms of willingness to continue treatment, on-demand treatment with esomeprazole 20 mg was non-inferior to continuous maintenance treatment and reduced medication usage in patients with NERD who had achieved symptom control with initial esomeprazole treatment. TRIAL REGISTRATION: ClinicalTrials.gov identifier (NCT number): NCT02670642 ; Date of registration: December 2015.

Forceps versus snare polypectomies in colorectal cancer screening: are we adhering to the guidelines?

BACKGROUND AND STUDY AIMS: European guidelines for quality assurance in colorectal cancer screening recommend snare resection for polyps > 5 mm. The aim of this study was to investigate polypectomy technique according to lesion size and shape, and to assess adherence of endoscopists enrolled in the national quality assurance program to the European guidelines. PATIENTS AND METHODS: This cohort study included screening colonoscopies performed between 2007 and 2013 within a quality assurance program in Austria. Resection technique was analyzed according to lesion characteristics and endoscopy facility (private practices, hospitals, outpatient clinics) before publication of the EU guidelines (2007 - 2010) and adherence to the guidelines after publication (2011 - 2013). All surveillance colonoscopies and examinations with missing data were excluded. RESULTS: A total of 128 969 screening colonoscopies performed by 278 endoscopy units were included. The polyp detection rate was 39.6 % (n = 47 797) and 95.6 % of polyps were resected. Of polyps ≥ 5 mm, 46.0 % were resected using forceps and were therefore not treated in accordance with the guidelines. Forceps polypectomy of lesions 5 - 10 mm and > 10 mm decreased significantly in hospitals after implementation of the guidelines (both P < 0.0001). In private practices, there was no difference in forceps usage for polyps of 5 - 10 mm (P = 0.41) before and after the guidelines, and for polyps > 10 mm forceps usage even increased (P < 0.0001). Endoscopists' forceps removal rates for polyps ≥ 5 mm correlated significantly with respective adenoma detection rates (P = 0.0007, r p  - 0.187) and cecal intubation rates (P = 0.0001, r p  - 0.303). Among endoscopists in private practices, internists had slightly lower forceps removal rates for polyps ≥ 5 mm than surgeons, both before (47.2 % vs. 50.7 %; P = 0.014) and after publication of the guidelines (51.9 % vs. 53.5 %; P = 0.161). CONCLUSIONS: This study confirmed the importance of the European guidelines. The inclusion of adequate resection technique as a quality indicator in colorectal cancer screening programs is recommended.

Endoscopists with low adenoma detection rates benefit from high-definition endoscopy.

BACKGROUND: An endoscopists adenoma detection rate (ADR) of less than 20 % correlates with high risk for occurrence of interval cancer. The impact of high-definition (HD) imaging on the ADR is discussed controversially. We aimed to investigate whether detection rates of individual endoscopists increase within 1 year before and 1 year after the switch from standard to HD endoscopy. METHODS: This cohort study analyzed 6,330 screening colonoscopies (2,968 with standard and 3,362 with HD) performed by 42 endoscopists between November 2007 and March 2013 within a nationwide quality assurance program for screening colonoscopy. RESULTS: The ADR of endoscopists with a low ADR (<20 %) increased significantly higher (from 11.8 to 18.1 %, p = 0.003) than of those with a high ADR (≥ 20 %) (from 28.6 to 30.7 %, p = 0.439) after switch from standard to HD colonoscopes (p = 0.0076). The proportion of endoscopists with an ADR < 20 % decreased from 45 to 42.9 % (p = 0.593). There was no significant increase in age- and sex-adjusted detection rates of adenomas (20.2 vs 23.7 %; p = 0.089), advanced adenomas (4.7 vs 5.5 %; p = 0.479), flat adenomas (2.7 vs 3.1 %; p = 0.515), polyps (38.8 vs 41.5 %; p = 0.305), proximal polyps (18.5 vs 20 %; p = 0.469) and hyperplastic polyps (15 vs 17.2 %; p = 0.243) of endoscopists after switch to HD colonoscopes. There was no difference in detection rates of flat polyps (5.5 vs 5.5 %; p = 0.987). CONCLUSIONS: The use of HD scopes is associated with marginal improvement in adenoma detection rates limited to those endoscopists with low adenoma detection rates prior to its introduction.

High quality of screening colonoscopy in Austria is not dependent on endoscopist specialty or setting.

BACKGROUND AND STUDY AIM: International studies have shown differences in the outcome of screening colonoscopies related to the endoscopist's specialty and setting of colonoscopy. The aim of this study was to investigate the impact of these two factors on quality parameters for screening colonoscopy in a quality-assured screening program. METHODS: Adenoma detection rate (ADR), cecal intubation rate (CIR), polypectomy rate, flat polyp detection rate, carcinoma detection rate, sedation rate, complication rates, and other parameters of 59 901 screening colonoscopies performed by 178 endoscopists were analyzed in relation to specialty (35 gastroenterologists: 10 066 colonoscopies [16.8 %]; 84 nongastroenterologists: 26 271 colonoscopies [43.9 %]; 59 surgeons: 23 564 [39.3 %]), and setting (hospital: 12 580 [21.6 %] colonoscopies; office: 45 781 [78.4 %] colonoscopies). RESULTS: The overall ADR was 20.5 % and the CIR was 95.6 %. The ADR did not show any statistical significance, either in relation to specialty or to setting. A significant difference in the CIR was found between hospital-based and office-based internists (98.5 % vs. 96.8 %, respectively; P  = 0.0005; odds ratio [OR] 2.2, 95 % confidence interval [CI] 1.4 - 3.4). Hospital-based internists had a significantly higher flat polyp detection rate (7.5 % vs. 4.1 %; P  = 0.02; OR 1.9, 95 %CI 1.1 - 3.2) and a significantly lower carcinoma detection rate (0.4 % vs. 0.6 %; P  = 0.03; OR 0.7, 95 %CI 0.5 - 1.0) compared with office-based internists. Complication rates were significantly lower among surgeons than among internists (0.1 % vs. 0.2 %; P  = 0.03; OR 0.5, 95 %CI 0.3 - 1.0). CONCLUSION: Endoscopists participating in the Austrian quality assurance program offered high quality screening colonoscopy regardless of their specialty and setting. The implementation of a standardized quality program is therefore a decisive factor in quality improvement of screening colonoscopy.

Sex is a stronger predictor of colorectal adenoma and advanced adenoma than fecal occult blood test.

Due to high costs and limited availability of screening colonoscopy, some screening programs require a positive fecal occult blood test (FOBT) before screening colonoscopy is remunerated. As male sex is a strong predictor of adenoma and advanced adenoma, we evaluated whether a positive FOBT or male sex is a stronger risk factor for adenoma and advanced adenoma. FOBT and screening colonoscopy results from 18.665 consecutive patients participating in a "national health check program" between 2009 and 2011 were included in this cohort study. Age-corrected adenoma detection rates (ADR), advanced adenoma detection rates (AADR) and carcinoma detection rates were calculated for men and women according to FOBT result separately. ADR and AADR in FOBT-positive men (34.6 and 11.8 %) and FOBT-negative men (29.1 and 7.6 %) were higher than ADR and AADR in FOBT-positive women (20 and 6.9 %) and in FOBT-negative women (17.6 and 4.4 %), (p = 0.0003). Men with negative FOBT were at higher risk of having an adenoma and advanced adenoma than women with positive FOBT (p < 0.0001). Odds ratios of a positive FOBT for ADR and AADR were 1.3 (1.1-1.5) (p = 0.0047) and 1.6 (1.2-2.1) (p < 0.0001), respectively. Odds ratios of male sex to predict ADR and AADR were significantly higher with 1.9 (1.8-2.1) and 1.8 (1.6-2), respectively (p < 0.001). Male sex is a stronger predictor for colorectal adenoma and advanced adenoma than positive FOBT. These results should be taken into account analyzing FOBT-based screening programs.

Sedation in screening colonoscopy: impact on quality indicators and complications.

OBJECTIVES: Quality indicators including cecal intubation rate (CIR) and adenoma detection rate (ADR) are established. Sex differences of quality indicators are observed, but the influence of sedation has not been investigated so far. The objective of this study is to assess the impact of sedation on quality indicators, including CIR and ADR, according to sex. METHODS: We analyzed data of 52,506 screening colonoscopies performed by 196 endoscopists between November 2007 and April 2011 according to the Austrian "quality management for colon cancer prevention" program. RESULTS: Sedation did not affect polyp detection rate (women P=0.7972, men P=0.3711) or ADR for both sexes (women P=0.2773, men P=0.8676). ADR was not significantly influenced by sedation (P=0.1272), but by age and sex (both P<0.0001), when the executing endoscopist was considered. Although women were more often sedated than men (90.70 vs. 81.83%; P<0.0001), CIR was slightly lower in women than in men (94.69 vs. 96.58%; P<0.0001). Sedation improved the CIR in women by 2.95% (94.96 vs. 92.01%; P<0.0001), whereas in men it was just by 1.28% (96.81 vs. 95.53%; P<0.0001). Sedated women only reached the CIR of unsedated men (94.96 vs. 95.53%; P=0.1005). Accounting for the intra-observer influence of the endoscopist, the overall CIR was influenced by the interaction of sex and age (P=0.0049), but not by sedation (P=0.1435). CONCLUSIONS: Sedation does not increase adenoma or polyp detection, although it leads to an increase in CIR in men and women. This effect is more pronounced in women, yet CIR of men remains higher compared with women. Quality indicators are mainly influenced by the patient's age, sex, and the endoscopists' individual performance, rather than the endoscopists' subspeciality or procedural experience.

Sex-specific prevalence of adenomas, advanced adenomas, and colorectal cancer in individuals undergoing screening colonoscopy.

CONTEXT: Although some studies have shown that men are at greater age-specific risk for advanced colorectal neoplasia than women, the age for referring patients to screening colonoscopy is independent of sex and usually recommended to be 50 years. OBJECTIVE: To determine and compare the prevalence and number needed to screen (NNS) for adenomas, advanced adenomas (AAs), and colorectal carcinomas (CRCs) for different age groups in men and women. DESIGN, SETTING, AND PATIENTS: Cohort study of 44,350 participants in a national screening colonoscopy program over a 4-year period (2007 to 2010) in Austria. MAIN OUTCOME MEASURES: Prevalence and NNS of adenomas, AAs, and CRCs in different age groups for men and women. RESULTS: The median ages were 60.7 years (interquartile range [IQR], 54.5-67.5 years) for women and 60.6 years (IQR, 54.3-67.6 years) for men, and the sex ratio was nearly identical (51.0% [22,598] vs 49.0% [21,572]). Adenomas were found in 19.7% of individuals screened (95% CI, 19.3%-20.1%; n = 8743), AAs in 6.3% (95% CI, 6.1%-6.5%; n = 2781), and CRCs in 1.1% (95% CI, 1.0%-1.2%; n = 491); NNS were 5.1 (95% CI, 5.0-5.2), 15.9 (95% CI, 15.4-16.5), and 90.9 (95% CI, 83.3-100.0), respectively. Male sex was significantly associated with a higher prevalence of adenomas (24.9% [95% CI, 24.3%-25.4%] vs 14.8% [95% CI, 14.3%-15.2%]; P < .001; unadjusted odds ratio [OR], 1.9 [95% CI, 1.8-2.0]), AAs (8.0% [95% CI, 7.6%-8.3%] vs 4.7% [95% CI, 4.4%-4.9%]; P < .001; unadjusted OR, 1.8 [95% CI, 1.6-1.9]), and CRCs (1.5% [95% CI, 1.3%-1.7%] vs 0.7% [95% CI, 0.6%-0.9%]; P < .001; unadjusted OR, 2.1 [95% CI, 1.7-2.5]). The prevalence of AAs in 50- to 54-year-old individuals was 5.0% (95% CI, 4.4%-5.6%) in men but 2.9% (95% CI, 2.5%-3.4%) in women (adjusted P = .001); the NNS in men was 20 (95% CI, 17.8-22.6) vs 34 in women (95% CI, 29.1-40; adjusted P = .001). There was no statistical significance between the prevalence and NNS of AAs in men aged 45 to 49 years compared with women aged 55 to 59 years (3.8% [95% CI, 2.3%-6.1%] vs 3.9% [95% CI, 3.3%-4.5%] and 26.1 [95% CI, 16.5-44.4] vs 26 [95% CI, 22.5-30.2]; P = .99). CONCLUSION: Among a cohort of Austrian individuals undergoing screening colonoscopy, the prevalence and NNS of AAs were comparable between men aged 45 to 49 years and women aged 55 to 59 years.

Association of IGF1 and IGFBP3 polymorphisms with colorectal polyps and colorectal cancer risk.

PURPOSE: Insulin-like growth factor 1 (IGF1) is a peptide growth factor that promotes cell proliferation and inhibits apoptosis. The bioavailability of IGF1 is regulated by the insulin-like growth factor binding protein 3 (IGFBP3). The purpose of this study was to examine the association of genetic variants in IGF1 (rs6214, rs6220, and rs35767) and IGFBP3 (rs2854744 and rs2854746) with risk of colorectal polyps and colorectal cancer. METHODS: In this ongoing colorectal cancer study of Austria (CORSA), a total of 3,360 Caucasian participants, consisting of 178 colorectal cancer patients, 328 patients with high risk polyps, 1,059 patients with low risk colorectal polyps, and 1,795 colonoscopy-negative controls, were recruited within a large colorectal screening project in the province Burgenland and from three hospitals in Vienna. Multiple logistic regression was applied to compare individuals of the control group against three different risk groups, namely, colorectal cancer group, high risk polyp group, and low risk polyp group. RESULTS: Carriers of the homozygous polymorphic genotype of the SNP rs6214 were associated with an increased colorectal risk (OR = 1.79, 95% CI 1.04-1.90) compared to the colonoscopy-negative controls; this was also found when combining colorectal cancer cases and high risk polyp group (OR = 1.39, 95% CI 1.01-1.90). CONCLUSION: Our results suggest that the SNP rs6214 of IGF1 could have an impact on developing colorectal cancer and colorectal polyps with villous elements.

Non-radial oscillation modes with long lifetimes in giant stars.

Towards the end of their lives, stars like the Sun greatly expand to become red giant stars. Such evolved stars could provide stringent tests of stellar theory, as many uncertainties of the internal stellar structure accumulate with age. Important examples are convective overshooting and rotational mixing during the central hydrogen-burning phase, which determine the mass of the helium core, but which are not well understood. In principle, analysis of radial and non-radial stellar oscillations can be used to constrain the mass of the helium core. Although all giants are expected to oscillate, it has hitherto been unclear whether non-radial modes are observable at all in red giants, or whether the oscillation modes have a short or a long mode lifetime, which determines the observational precision of the frequencies. Here we report the presence of radial and non-radial oscillations in more than 300 giant stars. For at least some of the giants, the mode lifetimes are of the order of a month. We observe giant stars with equally spaced frequency peaks in the Fourier spectrum of the time series, as well as giants for which the spectrum seems to be more complex. No satisfactory theoretical explanation currently exists for our observations.

CoRoT measures solar-like oscillations and granulation in stars hotter than the Sun.

Oscillations of the Sun have been used to understand its interior structure. The extension of similar studies to more distant stars has raised many difficulties despite the strong efforts of the international community over the past decades. The CoRoT (Convection Rotation and Planetary Transits) satellite, launched in December 2006, has now measured oscillations and the stellar granulation signature in three main sequence stars that are noticeably hotter than the sun. The oscillation amplitudes are about 1.5 times as large as those in the Sun; the stellar granulation is up to three times as high. The stellar amplitudes are about 25% below the theoretic values, providing a measurement of the nonadiabaticity of the process ruling the oscillations in the outer layers of the stars.

Differential diagnosis of benign and malign pancreatic masses with 18F-fluordeoxyglucose-positron emission tomography recorded with a dual-head coincidence gamma camera.

INTRODUCTION: Metabolic imaging using 18F-fluordeoxyglucose and a ring-positron emission tomography camera is an established method in the differential diagnosis of pancreatic masses. Ring-positron emission tomography cameras, however, are expensive and available in only few specialized centres. The aim of this study was to investigate how far 18F-fluordeoxyglucose scan with a conventional dual-head gamma-camera could differentiate between benign and malign pancreatic masses. MATERIAL AND METHODS: Forty-one patients (male/female: 25/16; mean age: 64.0 years; range: 41-86 years) with a pancreatic mass detected by ultrasound, computed tomography or MRI were included. In all patients 18F-fluordeoxyglucose scan was performed after overnight fasting and injection of 4 mCi 18F-fluordeoxyglucose using an ADAC Vertex MCD dual head gamma-camera (ADAC; Milpitas, California, USA), equipped with a 5/8-inch NaI-crystal. Images were acquired through a 180 degrees grade rotation in the three dimensional mode. The chosen matrix was 128 x 128 x 16, a Butterworthfilter (ADAC) was used and data were transferred into visible sinograms via Fourier-Rebinning. Coronar, sagittal and transversal slices of 3.9 mm thickness each were acquired. Focal tracer enhancement was suspicious for a malignoma and therefore regarded as positive, diffuse or no tracer uptake was suspicious for a benign process and was regarded as negative for cancer. DEFINITION OF GOLD STANDARDS: A diagnosis of cancer had to be confirmed histologically by specimens obtained by 18G-needle biopsy, surgical resection or at autopsy. A diagnosis of an inflammatory mass was considered proven, if no carcinoma could be found histologically in the surgically resected mass or at autopsy, or if there was no progression of the disease during a follow-up of at least 12 months. RESULTS: In 22 patients carcinoma was diagnosed (pancreatic cancer: n=17; endocrine tumour: n=3; carcinoma of the common bile duct: n=2). 18F-fluordeoxyglucose scan showed a focal tracer enhancement in 19 of these 22 patients (sensitivity: 86.4%). False negative results were acquired in two patients with cancer of the common bile duct and in one patient with poorly controlled insulin-dependent diabetes mellitus. In 19 patients the final diagnosis was an inflammatory pancreatic mass. 18F-fluordeoxyglucose scan showed a diffuse tracer enhancement in 15 of these 19 patients (specificity: 78.9%). False positive results were acquired in three patients whose blood tests showed signs of an acute episode of chronic pancreatitis. Positive and negative predictive values of 18F-fluordeoxyglucose scan were 82.6% and 83.3%, respectively. CONCLUSION: 18F-fluordeoxyglucose scan with a conventional dual-head gamma-camera is a highly sensitive and specific method in the differential diagnosis of benign and malign pancreatic masses.

The challenge presented by right atrial myxoma.

BACKGROUND AND PURPOSE: Right atrial myxoma can be heralded by nonspecific constitutional symptoms-i. e., remittent or lasting fever; weight loss; chronic anemia and general arthralgia-and may escape timely diagnosis until severe complications develop: i. e., pulmonary hypertension due to embolism from fragments originating from the tumor mass, or, by blocking the right atrioventricular ostium, a Budd-Chiari syndrome with acute abdominal pain. Myocardial tamponade and infected right atrial myxomas are reported casuistically. META-ANALYSIS: This study, covering 1,029 patients from 32 reports, represents the most extensive meta-analysis to date of recent publications on patients with intracardiac myxomas who had undergone surgery followed by histological confirmation. 83.0% of myxomas studied were located in the left and 12.7% in the right atrial cavity. Even more rarely, the tumor was present in the left (0.6%) or right (1.7%) ventricles; it was biatrial in 1.3% and multilocular in 0.8% of cases. The age of all reported individuals varied between 1 month and 81 years (mean value of reported mean ages: 50 years); 65% of the patients were female. In a subpopulation of 154 individuals, the fraction of familial cardiac myxomas was 4.5%. CASE STUDY: For a 68-year-old patient with recurrent fever of unknown origin, weight loss, exertional dyspnea, and tachycardia, the authors further describe epidemiology, clinical symptoms, prognosis, and the specific diagnostic and therapeutic challenges involved in the rare case of a right sided atrial myxoma.

No stellar p-mode oscillations in space-based photometry of Procyon.

Pressure-driven (p-mode) oscillations at the surface of the Sun, resulting from sound waves travelling through the solar interior, are a powerful probe of solar structure, just as seismology can reveal details about the interior of the Earth. Astronomers have hoped to exploit p-mode asteroseismology in Sun-like stars to test detailed models of stellar structure and evolution, but the observations are extremely difficult. The bright star Procyon has been considered one of the best candidates for asteroseismology, on the basis of models and previous reports of p-modes detected in ground-based spectroscopy. Here we present a search for p-modes in 32 days of nearly continuous photometric satellite-based observations of Procyon. If there are p-modes in Procyon, they must have lifetimes less than 2-3 days and/or peak amplitudes <15 parts per million, which defy expectations from the Sun's oscillations and previous theoretical predictions. Target selection for future planned asteroseismology space missions may need to be reconsidered, as will the theory of stellar oscillations.

High-grade dysplasia and invasive carcinoma in colorectal adenomas: a multivariate analysis of the impact of adenoma and patient characteristics.

BACKGROUND AND AIMS: Most colorectal carcinomas develop from preformed adenomas, but only a minority of adenomas undergo malignant transformation. The clinical significance of polyps of size < 0.5 cm is controversial. The primary goal of this study was to assess the independent risk factors of adenoma and patient characteristics associated with advanced pathological features (APF; i.e. high-grade dysplasia or invasive carcinoma) in colorectal adenomas. A secondary goal was to assess the malignant potential of adenomas with a diameter of < 0.5 cm. PATIENTS AND METHODS: Patients who underwent total colonoscopy at our Medical Department between 1978 and 1996 and had at least one colorectal adenoma were considered for this study. Patients with a history of colorectal cancer, prior polypectomy or colorectal surgery were excluded. A total of 7590 adenomas removed from 4216 patients were included in this analysis. Logistic regression analysis was used to study the impact of different adenoma and patient characteristics on the risk of APF. RESULTS: Size proved to be the most important risk factor for APF. The percentage of adenomas with APF was 3.4%, 13.5% and 38.5% for adenomas of diameter < 0.5 cm, 0.5-1 cm and > 1 cm, respectively. Villous or tubulovillous histology, left-sided location and age >or= 60 years were also associated with APF, whereas sex and number of adenomas had no significant impact. Logistic regression analysis revealed that the risk of an adenoma containing APF was best described by a model incorporating the factors size, location, age, and the age by histology interaction. In the class of adenomas with diameter < 0.5 cm, no invasive carcinoma was found, but 3.4% of adenomas had high-grade dysplasia. CONCLUSIONS: The risk of a colorectal adenoma containing APF can be estimated only by a complex model taking into account several adenoma and patient characteristics. Size, histological type, location and age are independent risk factors for APF in colorectal adenomas. As a considerable percentage of adenomas with diameter < 0.5 cm contain high-grade dysplasia, the clinical conclusion from our study is that all adenomas, including those with diameter < 0.5 cm, should be removed whenever possible.