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Nereo Segnan

Publications and source records attributed to Nereo Segnan.

At least 19 recordsLinked to original sources

HPV triage for low grade (L-SIL) cytology is appropriate for women over 35 in mass cervical cancer screening using liquid based cytology.

In the experimental arm of a randomised trial, women were tested both for liquid-based cytology and human papillomavirus (HPV) DNA and referred for colposcopy if cytology was ASCUS (atypical cells of undetermined significance) or more severe. We considered those with ASCUS (757) or LSIL (low-grade squamous intraepithelial lesions) (485) and a valid HPV test who received colposcopy. We computed sensitivity, specificity and ROC curves with different values of relative light units (RLU, that are related to viral load) as cut off, using cervical intraepithelial neoplasia grade 2 or more severe (CIN2+) at blind histology review as the endpoint. The area under the receiver operating characteristic (ROC) curve was significantly less among women aged 25-34 years than in those older, both considering ASCUS/AGUS (atypical glandular cells of undetermined significance) (p=0.0355) and LSIL (p=0.0009). At age 35-60 the curves for ASCUS and LSIL were similar, while at age 25-34 the area under the curve for LSIL was significantly less than for ASCUS (p=0.0084). With LSIL cytology, specificity of Hybrid Capture 2 with 2 RLU cut-off was 35.0% (95%CI 28.4-42.1) at age 25-34 and 64.5% (95%CI 58.3-70.3) at age 35-60. In conclusion, triaging by HPV testing performed better in women aged over 35 years than those younger. For older women, HPV triaging should also be considered for managing those with LSIL cytology.

Adult↗

Accessibility as a major determinant of radiotherapy underutilization: a population based study.

BACKGROUND AND PURPOSE: A survey was conducted of radiotherapy (RT) resources and utilization in a northwestern Italian Region in order to assess geographical variations in radiotherapy utilization rates, and the effects of infrastructure supply on accessibility. MATERIALS AND METHODS: The survey was conducted by analysing standardized utilization rates based on administrative records. The data were analysed at both Regional and Local Health Unit (LHU) level. RESULTS: Wide variation was found among LHUs RT utilization rates--the sex- and age-standardized rates varied from 1.8/1000 inhabitants to more than 3/1000 inhabitants. Patients resident in LHUs with no RT service showed a lower probability of accessing RT (standardized rate ratio (SRR), 0.82; 95%IC, 0.80-0.85). The utilization rate decreased in relation to the distance between a patient's residence and the nearest RT service; the reduction was greater for patients > or =70 years of age. CONCLUSION: The wide geographic variation implies lack of equity in access to services. Utilization levels decreased significantly with increasing distance from the nearest RT service, distance being a barrier to access particularly for older persons. The heterogeneous distribution of services on the Regional territory seems a relevant explanation of differences in utilization rates.

Community Health Planning↗

Human papillomavirus testing and liquid-based cytology: results at recruitment from the new technologies for cervical cancer randomized controlled trial.

BACKGROUND: Although testing for human papillomavirus (HPV) has higher sensitivity and lower specificity than cytology alone for detecting cervical intraepithelial neoplasia (CIN), studies comparing conventional and liquid-based cytology have had conflicting results. METHODS: In the first phase of a two-phase multicenter randomized controlled trial, women aged 35-60 years in the conventional arm (n = 16,658) were screened using conventional cytology, and women in the experimental arm (n = 16,706) had liquid-based cytology and were tested for high-risk HPV types using the Hybrid Capture 2 assay. Women in the conventional arm were referred to colposcopy with atypical cells of undetermined significance (ASCUS) or higher and those in the experimental arm were referred with ASCUS or higher cytology or with a positive (> or = 1 pg/mL) HPV test. Sensitivity and positive predictive value (PPV) for detection of cervical intraepithelial neoplasia grade 2 or higher (CIN2+) were calculated. RESULTS: The screening methods and referral criterion applied in the experimental arm had higher sensitivity than that in the conventional arm (relative sensitivity = 1.47; 95% confidence interval [CI] = 1.03 to 2.09) but a lower PPV (relative PPV = 0.40; 95% CI = 0.23 to 0.66). With HPV testing alone at > or = 1 pg/mL and at > or = 2 pg/mL, the gain in sensitivity compared with the conventional arm remained similar (relative sensitivity = 1.43, 95% CI = 1.00 to 2.04 and relative sensitivity = 1.41, 95% CI = 0.98 to 2.01, respectively) but PPV progressively improved (relative PPV = 0.58, 95% CI = 0.33 to 0.98 and relative PPV = 0.75, 95% CI = 0.45 and 1.27, respectively). Referral based on liquid-based cytology alone did not increase sensitivity compared with conventional cytology (relative sensitivity = 1.06; 95% CI = 0.72 to 1.55) but reduced PPV (relative PPV = 0.57; 95% CI = 0.39 to 0.82). CONCLUSIONS: HPV testing alone was more sensitive than conventional cytology among women 35-60 years old. Adding liquid-based cytology improved sensitivity only marginally but increased false-positives. HPV testing using Hybrid Capture 2 with a 2 pg/mL cutoff may be more appropriate than a 1 pg/mL cutoff for primary cervical cancer screening.

Adult↗

Human papillomavirus typing with GP5+/6+ polymerase chain reaction reverse line blotting and with commercial type-specific PCR kits.

BACKGROUND: Infection with human papillomavirus (HPV) is a necessary step in the progression to cervical cancer. Many methods for HPV testing are currently available, most developed to detect pools of HPV types. OBJECTIVES: To evaluate the HPV typing by molecular methods and to compare commercial kits with an established laboratory method. STUDY DESIGN: Eighty-four cervical samples found to be positive for HPV DNA by GP5+/6+-polymerase chain reaction-enzyme immunoassay-reverse line blotting (PCR-EIA-RLB) were re-tested with two commercial methods, INNO-LiPA and Amplisense HPV typing, able to identify the HPV type predicted by PCR-EIA-RLB in 76 and 67 samples, respectively. RESULTS: The INNO-LiPA assay revealed HPV DNA in 75/76 samples (98.7%; 95% CI, 0.93-0.99) that would contain HPV types identifiable by this assay. The Amplisense HPV assay revealed HPV DNA in 58/67 samples (86.6%; 95% CI, 0.76-0.93) containing HPV types detectable by this assay. For samples with a single infection, the unweighted kappa for concordance of HPV typing was 0.87 (95% CI, 0.78-0.97) for PCR-EIA-RLB versus INNO-LiPA, 0.94 (95% CI, 0.87-0.99) for INNO-LiPA versus Amplisense HPV, and 0.82 (95% CI, 0.70-0.94) for PCR-EIA-RLB versus Amplisense HPV typing. PCR-EIA-RLB revealed 12 multiple infections, INNO-LiPA revealed 14, and Amplisense HPV revealed 5. The agreement among tests for samples with multiple infections was lower, giving kappa values of 0.44 (95% CI, 0.18-0.70) for PCR-EIA-RLB versus INNO-LiPA, 0.52 (95% CI, 0.19-0.85) for PCR-EIA-RLB versus Amplisense HPV and 0.43 (95% CI, 0.12-0.74) for INNO-LiPA versus Amplisense HPV. CONCLUSIONS: In HPV-positive samples, the agreement among tests for HPV typing was high for single infections but markedly lower for infections with multiple HPV types.

Adult↗

Human papillomavirus testing and liquid-based cytology in primary screening of women younger than 35 years: results at recruitment for a randomised controlled trial.

BACKGROUND: Testing for human papillomavirus (HPV) DNA is more sensitive but less specific than cytological analysis. Loss in specificity is most relevant in women younger than 35 years because of increased HPV prevalence. We aimed to compare conventional screening with an experimental strategy in women aged 25-34 years, and investigate the effect of different criteria of referral to define the best methods of HPV screening. METHODS: Women were randomly assigned to the conventional procedure (standard cytology, with referral to colposcopy if cytology showed atypical squamous cells of undetermined significance or more [ASCUS+]) or an experimental procedure (liquid-based cytology and testing for high-risk HPV types, with referral to colposcopy with ASCUS+ cytology). Women positive for HPV (cutoff > or = 1 pg/mL) but with normal cytology were retested after 1 year. The main endpoint was the presence of cervical intraepithelial neoplasia at grade 2 or more (CIN2+) in reviewed histology. The main analysis was by intention to screen. This trial is registered as an International Standard Randomised Controlled Trial, number ISRCTN81678807. FINDINGS: We randomly assigned 5808 women aged 25-34 years to the conventional group and 6002 to the experimental group. The experimental procedure was significantly more sensitive than the conventional procedure (55 vs 33 CIN2+ lesions detected; relative sensitivity 1.61 [95% CI 1.05-2.48]), but had a lower positive predictive value (PPV; relative PPV 0.55 [0.37-0.82]). HPV testing (> or = 1 pg/mL) with cytology triage was also more sensitive than conventional cytology (relative sensitivity 1.58 [1.03-2.44], relative PPV 0.78 [0.52-1.16]). Relative PPV could be improved, with minimum loss in sensitivity, by use of a 2 pg/mL cutoff for HPV testing. Compared with conventional cytology, liquid-based cytology had a relative sensitivity of 1.32 (0.84-2.06), relative PPV 0.58 [0.38-0.89]). INTERPRETATION: HPV testing alone with cytology triage could be a feasible alternative to conventional cytology for screening women younger than 35 years. Follow-up will provide data on possible overdiagnosis and on the feasibility of extended intervals.

Adult↗

Estimate of overdiagnosis of breast cancer due to mammography after adjustment for lead time. A service screening study in Italy.

INTRODUCTION: Excess of incidence rates is the expected consequence of service screening. The aim of this paper is to estimate the quota attributable to overdiagnosis in the breast cancer screening programmes in Northern and Central Italy. METHODS: All patients with breast cancer diagnosed between 50 and 74 years who were resident in screening areas in the six years before and five years after the start of the screening programme were included. We calculated a corrected-for-lead-time number of observed cases for each calendar year. The number of observed incident cases was reduced by the number of screen-detected cases in that year and incremented by the estimated number of screen-detected cases that would have arisen clinically in that year. RESULTS: In total we included 13,519 and 13,999 breast cancer cases diagnosed in the pre-screening and screening years, respectively. In total, the excess ratio of observed to predicted in situ and invasive cases was 36.2%. After correction for lead time the excess ratio was 4.6% (95% confidence interval 2 to 7%) and for invasive cases only it was 3.2% (95% confidence interval 1 to 6%). CONCLUSION: The remaining excess of cancers after individual correction for lead time was lower than 5%.

Aged↗

Early diagnosis, not differential treatment, explains better survival in service screening.

Italian population-based breast cancer screening programmes with 2-year, high-quality mammography started in the cities of Florence and Turin in the early 1990s. Breast cancer cases from the local Tumour Registry were classified by method of detection and tumour characteristics (size, nodal-status and grade). Follow-up was at December 2001. In total, 4444 breast cancer cases were analysed. The Hazard Ratio comparing before and after-invitation breast cancer cases indicated a 27% reduction (HR=0.73; 95%CI: 0.61-0.87) in the risk of dying for the disease. After adjustment for tumour characteristics, survival rate was comparable by invitation status, whereas the proportion of early cancer was 33.7% and 46.6% in the before and after-invitation group. Survival rates by tumour characteristic subgroups was comparable by invitation status. Late stage and grade 3 were indicators of poor prognosis. Adjustment for tumour characteristics confirmed screening and not differential treatment as the most important reason for the observed survival benefit. The survival analysis by specific subgroups did not support the hypothesis that the difference in prognosis was attributable to differential treatment.

Aged↗

History of negative colorectal endoscopy and risk of rectosigmoid neoplasms at screening flexible sigmoidoscopy.

BACKGROUND AND AIMS: Screening sigmoidoscopy can reduce incidence of colorectal cancer and mortality. The optimal re-screening interval has not yet been defined. This study is aimed at estimating the risk of distal advanced adenomas (diameter >/=10 mm, villous component >20%, high-grade dysplasia) and cancer at screening flexible sigmoidoscopy in subjects aged 55-64 years who reported pre-screening negative colorectal endoscopy. PATIENTS: Eight thousands two hundred two subjects aged 55-64 years who underwent screening flexible sigmoidoscopy within the SCORE trial in Italy and who were able to report their previous history of colorectal endoscopy. RESULTS: Eight hundred eighty three of 8,202 subjects (10.8%) reported at least one prescreening negative endoscopy: among them, after 3-5 years, 6-10 years and >10 years intervals between last reported examination and screening endoscopy, the Absolute Risk of advanced adenomas was 1.5%, 0.9% and 0.9%; one cancer was detected (0.1%). Among the 7,319 subjects who did not report prescreening endoscopy the risks of advanced adenoma and cancer were 3.2% and 0.4%, respectively. Subjects with a previous colorectal examination had a 65% decreased risk of advanced adenomas (OR=0.35, 95%CI 0.18-0.66) and a 71% decreased risk of cancer (OR=0.29, 95%CI 0.04-1.12) as compared to those who did not. For subjects without family history of colorectal cancer the statistically significant decrease of the risk persisted up to ten years. The observed benefit seems not to apply to subjects with family history of colorectal cancer. CONCLUSIONS: Our results are consistent with the hypothesis that the interval between screening sigmoidoscopies could be safely expanded beyond 5 years for subjects without specific risk factors for colorectal cancer.

Adenoma, Villous↗

Randomized trial of different screening strategies for colorectal cancer: patient response and detection rates.

BACKGROUND: Although there is general consensus concerning the efficacy of colorectal cancer screening, there is a lack of agreement about which routine screening strategy should be adopted. We compared the participation and detection rates achievable through different strategies of colorectal cancer screening. METHODS: From November 1999 through June 2001 we conducted a multicenter, randomized trial in Italy among a sample of 55-64 year olds in the general population who had an average risk of colorectal cancer. People with previous colorectal cancer, adenomas, inflammatory bowel disease, a recent (< or =2 years) colorectal endoscopy or fecal occult blood test (FOBT), or two first-degree relatives with colorectal cancer were excluded. Eligible subjects were randomly assigned, within the roster of their general practitioner, to 1) biennial FOBT (delivered by mail), 2) biennial FOBT (delivered by general practitioner or a screening facility), 3) patient's choice of FOBT or "once-only" sigmoidoscopy, 4) "once-only" sigmoidoscopy, or 5) sigmoidoscopy followed by biennial FOBT. An immunologic FOBT was used. Participation and detection rates of the strategies tested were compared using multivariable logistic regression models that adjusted for age, sex, and screening center. All statistical tests were two-sided. RESULTS: Of 28 319 people sampled, 1637 were excluded and 26 682 were randomly assigned to a screening arm. After excluding undelivered letters (n = 427), the participation rates for groups 1, 2, 3, 4, and 5 were 30.1% (682/2266), 28.1% (1654/5893), 27.1% (970/3579), 28.1% (1026/3650), and 28.1% (3049/10 867), respectively. Of the 2858 subjects screened by FOBT, 122 (4.3%) had a positive test result, 10 (3.5 per 1000) had colorectal cancer, and 39 (1.4%) had an advanced adenoma. Among the 4466 subjects screened by sigmoidoscopy, 341 (7.6%) were referred for colonoscopy, 18 (4 per 1000) had colorectal cancer, and 229 (5.1%) harbored an advanced adenoma. CONCLUSIONS: The participation rates were similar for sigmoidoscopy and FOBT. The detection rate for advanced neoplasia was three times higher following screening by sigmoidoscopy than by FOBT.

Colonic Polyps↗

Prevalence of human papillomavirus infection in women in Turin, Italy.

Human papillomavirus (HPV) is recognised as necessary for the development of cervical cancer. An age-stratified random sample of 1013 women, aged 25-70 years, participating in the organised cervical screening programme in Turin, Italy was tested for 36 HPV types using polymerase chain reaction (PCR) with the general primers GP5+/GP6+. The overall HPV prevalence was 8.8%. High-risk types were found in 7.1% of women and multiple infections in 1.1%. HPV-16 was the most common type (32.6% of HPV-positive women). HPV prevalence (any type) was 13-14% at ages 25-39 years, 11.5% at age 40-44 years, and approximately 5% among older women. After age-adjustment, HPV prevalence was significantly increased in single vs married, (Odds Ratio (OR)=2.23; 95% Confidence Interval (CI): 1.28-3.89) and decreased in parous vs nulliparous women (OR=0.49; 95% CI: 0.31-0.78). However, the association with marital status and parity was restricted to women less than 45 years of age. In conclusion, overall, the female population of Turin showed an HPV prevalence that is intermediate compared with worldwide levels.

Adolescent↗

What information do breast cancer screening programmes provide to Italian women?

BACKGROUND: The necessity for building transparent communications on screening, both on risks and benefits, is shared by different sides. There is a general agreement that women cannot express informed participation in a screening programme unless they are given sufficient and adequate information. In the screening context, invitation letters and leaflets often represent the principal source of information. METHODS: The invitation letters and leaflets used by 60 Italian breast cancer screening programmes were collected and evaluated through a score sheet developed to verify what kind of information is provided to women. RESULTS: Fifty-three programmes (88.3%) answered and 47 (78.3%) were included in the analysis because of completeness of the material. Nearly all the programmes provide satisfactory practical information and explanations about the test and the screening aims. Few programmes mention the possibility of some discomfort during the exam (34.0%), quality assessment and operator training (10.6%), double reading (6.4%), radiation risk (6.4%) and data confidentiality (6.4%). 68.1% provide information about recall but none describes what a further assessment involves. Epidemiological and numerical information are present only occasionally. CONCLUSION: Although satisfactorily disclosing some practical information, Italian invitation letters and leaflets remain inadequate in managing side effects and risks. If accurate information has the potential to enable women to make an informed choice, the information inviting them to perform screening test must be improved. Further researcher is needed to evaluate different decision aids to meet women's desires for balanced information. KEY POINTS: Women cannot express informed participation in a breast screening programme unless they are given balanced information both on benefits and adverse effects. Current information screening tools often omit relevent data, fail to give information about pros and cons and ignore uncertainties. Despite these considerations, how much information should be given and how this should be framed remains still to be defined. Further evalutions of different ways of presenting information and women's information needs are urgently required.

Aged↗

Ascertainment and evaluation of interval cancers in population-based mammography screening programmes: a collaborative study in four European centres.

OBJECTIVES: The purpose of the present study was to estimate the interval cancer (IC) rates in four population-based mammography screening programmes in four countries with different health-care environments, different access to cancer registry data, and different age groups of women invited. SETTING: The screening programmes in Coimbra (Portugal), Dublin (Ireland), Stockholm (Sweden), and Turin (Italy) participated in the study. METHODS: All cancer cases were searched for in cancer registries. IC rates and other outcome measures from the screening programmes were estimated and compared between the centres. Poisson regression model was used to estimate the proportional incidence based on IC rate in relation to expected total breast cancer incidence rate in the absence of screening. RESULTS: There was a more than tenfold difference in the number of invited women at the first round between the involved centres. The IC rates varied between 4.3 and 23.8 per 10,000 women screened. The levels of IC rates in relation to the estimated background incidence varied from 0.35 up to 0.46 depending on age groups involved in the programme, but did not differ significantly between three of the four involved centres. CONCLUSIONS: IC rates were quite similar between three of the four centres despite the differences in target population, invited ages, length of building-up of the programmes and different health-care organizations. Different access to complete cancer registry data is likely to explain the lower IC rates in the fourth centre.

Breast Neoplasms↗

Predicting proximal advanced neoplasms at screening sigmoidoscopy.

PURPOSE: This study was designed to assess the predictive value for advanced proximal neoplasms (cancer, adenoma > or = 10 mm, or villous component > 20 percent, or severe dysplasia) of the characteristics of distal polyps. METHODS: The study was conducted among patients, aged 55 to 64 years, referred for colonoscopy in the Italian trial of sigmoidoscopy screening for colorectal cancer. Patients reporting a history of colorectal cancer, adenomas, inflammatory bowel disease, recent colorectal endoscopy, or two first-degree relatives with colorectal cancer were excluded. We compared the prevalence of advanced proximal neoplasia in patients with "low-risk" (1-2 tubular adenomas, < 10 mm, with low-grade dysplasia, or hyperplastic polyp) and in those with "high-risk" (size, > or = 10 mm, or > or = 3 adenomas, or villous component > 20 percent, or severe dysplasia) polyps in the distal colon. RESULTS: Of 426 patients with polyps > 5 mm, 29 (6.9 percent) were detected with an advanced proximal neoplasm (including 4 colorectal cancers). The prevalence of proximal advanced neoplasia was 9.4 percent among patients with high-risk distal polyps and 2.5 percent among those with low-risk lesions (adjusted odds ratio, 3.19; 95 percent confidence interval, 1.06-9.59). Approximately 40 people with low-risk distal polyps 6 to 9 mm should undergo colonoscopy to detect one proximal advanced neoplasm; the corresponding number for patients with high-risk distal polyps is 10. CONCLUSIONS: The 2.5 percent prevalence of proximal advanced neoplasms among people with low-risk 6-mm to 9-mm distal polyps is similar to the prevalence observed among people without distal polyps. Restricting colonoscopy referral to patients with high-risk distal polyps might represent a cost-effective strategy in a screening context.

Adenoma↗

Impact of the AutoPap (currently Focalpoint) primary screening system location guide use on interpretation time and diagnosis.

BACKGROUND: AutoPap (currently Focalpoint) is a computerized scanning system for the primary screening of cervicovaginal smears. For smears indicated to require further review, the system provides maps (PapMaps) to identify the most abnormal areas of the smear. METHODS: To study the effect of PapMaps on diagnosis, 481 smears (from 4656 successfully processed smears using AutoPap) were first classified by conventional manual interpretation and then reinterpreted blind by the same cytologist who limited his examination to only the fields of view marked by the PapMaps. The interpretation time with and without PapMaps was measured on another simple random sample of 188 smears. RESULTS: The interpretation time was reduced significantly, by approximately 40% using PapMaps (average reduction, 136 seconds per smear, 95% confidence interval [CI], 123-150). No cases manually classified as low-grade squamous intraepithelial lesions (LSIL) or worse and 20% of those manually classified as atypical squamous cells of undertermined significance (ASCUS) were judged as completely normal on the basis of fields of visions marked by PapMaps. In none of the latter was a histologically confirmed intraepithelial lesion identified. In relation to detailed diagnosis, the weighted kappa between manual and PapMap-aided interpretation was 0.745 (95% CI 0.687-0.804). Systematic differences were found (symmetry chi-square(10d.f) =19.11, P = 0.039): 48% of smears classified as ASCUS and 23% classified as LSIL by conventional diagnosis were classified as less severe (including normal) on the basis of PapMaps. CONCLUSIONS: Use of PapMaps resulted in a substantial reduction in interpretation time. PapMaps showed good sensitivity (100% for squamous intraepithelial lesions and 80% for ACSUC) for selecting abnormal slides. The latter require full examination: detailed diagnosis based only on areas marked by PapMaps could lead to under-grading.

Adult↗

Baseline findings of the Italian multicenter randomized controlled trial of "once-only sigmoidoscopy"--SCORE.

BACKGROUND: A single sigmoidoscopy examination at around age 60 years has been proposed as a cost-effective strategy to prevent colorectal cancer. A multicenter randomized controlled trial, the SCORE trial, is in progress in Italy to estimate the impact of this strategy on colorectal cancer incidence and mortality and the duration of the protective effect. We present the baseline screening outcomes. METHODS: A questionnaire was mailed to a random sample of 236 568 people aged 55-64 years to assess their eligibility for and interest in screening. Those reporting a history of colorectal cancer, adenomas, inflammatory bowel disease, recent colorectal endoscopy, or two first-degree relatives with colorectal cancer were excluded. Eligible, interested respondents were assigned randomly to the control group (no further contact) or the intervention group (invitation to undergo sigmoidoscopy). Screenees with colorectal cancer, polyps larger than 5 mm, three or more adenomas, adenomas 5 mm or smaller with a villous component of more than 20%, or severe dysplasia were referred for colonoscopy. RESULTS: Of the 56 532 respondents (23.9% of those invited), 34 292 were enrolled and 17 148 were assigned to the screening group. Of those, 9999 attended and 9911 were actually examined by sigmoidoscopy. Distal adenomas were detected in 1070 subjects (10.8%). Proximal adenomas were detected in 116 of 747 (15.5%) subjects without cancer at sigmoidoscopy who then underwent colonoscopy. A total of 54 subjects was found to have colorectal cancer, a rate of 5.4 per 1000 (54% of which were Dukes' A). The procedures were relatively safe, with two perforations (one in 9911 sigmoidoscopy exams and one in 775 colonoscopies) and one hemorrhage requiring hospitalization after polypectomy during colonoscopy. The pain associated with sigmoidoscopy was described as mild or less than expected by 83.3% of the screenees. CONCLUSION: Sigmoidoscopy screening is generally acceptable to recipients and safe. The high yield of advanced adenomas is consistent with the projected impact of sigmoidoscopy screening on colorectal cancer incidence.

Adenoma↗