Paul Rozen

A Quantitative Immunochemical Fecal Occult Blood Test for Colorectal Neoplasia

Context Although screening with a guaiac-based fecal occult blood test (FOBT) reduces colorectal cancer mortality, better tests are needed. Contribution In the study, 1000 patients undergoing diagnostic colonoscopy provided fecal samples that a clinical laboratory tested with a quantitative immunochemical test for hemoglobin. Hemoglobin content was highest in samples from people with significant neoplasia, for which sensitivity and specificity were 67% and 91%, respectively. Positive and negative likelihood ratios were 7.8 and 0.36, respectively. Cautions The authors did not compare the immunochemical FOBT with guaiac-based FOBT. The study included people with symptoms. Implications The quantitative immunochemical test for fecal hemoglobin is a promising test that needs evaluation in a screening population. The Editors A colorectal cancer screening test should identify persons with early-stage cancer that is an immediate medical threat and persons with advanced adenomas that could be a future threat. As well as having high sensitivity, the screening test should have high specificity for detecting clinically significant neoplasia, cancer, and advanced adenomas to minimize follow-up colonoscopy examinations (1). The commonly used guaiac-based fecal occult blood tests (FOBTs) have low specificity for detecting human hemoglobin and relatively low sensitivity for identifying clinically significant colorectal neoplasia (18). Office-developed qualitative immunochemical FOBTs are specific for detection of human hemoglobin and have improved test specificity (1, 46, 913). However, the manufacturers designed the test to have sensitivity for measuring hemoglobin similar to that of a sensitive guaiac-based FOBT, which is a limitation. Moreover, we found that doing the actual measuring in the office was not conducive to large-scale screening while maintaining quality control (1, 2, 6). We investigated a clinical laboratorybased immunochemical test that measures the hemoglobin content of a stool sample. Laboratory-based, automated, immunochemical measurement of fecal human hemoglobin eliminates the need for diet restrictions, is specific for human hemoglobin, and allows for quality control. In addition, clinicians can choose a fecal hemoglobin threshold level to perform colonoscopy and can adjust this threshold to take account of the patients risk for advanced neoplasia and the availability of quality colonoscopy (1, 1420). The quantitative immunochemical FOBT has been evaluated in Japan and elsewhere (1422). However, to our knowledge, no English-language publication systematically compares fecal immunochemical hemoglobin content with total colonoscopy findings. We aimed to measure the sensitivity and specificity of different levels of fecal hemoglobin for detecting clinically significant colorectal neoplasia versus colonoscopy, to determine the posttest probability of advanced neoplasia at different fecal hemoglobin threshold values, and to determine the optimal number of fecal samples. Methods Patients We asked consecutive ambulatory persons who were referred for colonoscopy to volunteer to prepare immunochemical FOBTs for research purposes. Some patients were asymptomatic and were invited for elective colonoscopy, some patients were at high risk for colorectal cancer (these patients were from our clinic), and some patients were symptomatic and were referred by their treating physician (Table 1 and Figure 1). We have reported partial findings on the initial 500 patients (20). Table 1. Baseline Characteristics* Figure 1. Study flow diagram. I-FOBT = immunochemical fecal occult blood test; IBD = inflammatory bowel disease. Exclusions were concurrent hospitalization, visible rectal bleeding, known diagnosis of inflammatory bowel disease, hematuria, menstruation at the time of obtaining a stool specimen, and inability to prepare the immunochemical FOBT (Figure 1). We did not exclude patients with long-term use of nonsteroidal anti-inflammatory drugs or anticoagulant therapy that was stopped for colonoscopy. Endoscopy and Lesions We inserted the colonoscope to the cecum or an obstructing carcinoma. We excluded 49 patients with an incomplete colonoscopy. Biopsy was done on lesions or they were removed, and their sites were noted. We classified abnormal findings by number of polyps, polyp sizes, and sites grouped by location (proximal [colon cecum to and including splenic flexure] or distal colon) and by histologic characteristics. The endoscopist estimated polyp size with a calibrated open biopsy forceps. We grouped adenomas and mass lesions by diameter or size (5 mm, 6 to 9 mm, or 10 mm) and by histologic characteristics (tubular, serrated, tubulovillous, or villous). We classified dysplasia as low grade or high grade. Pathologists were blinded to the immunochemical FOBT results. Clinically significant neoplasia includes colorectal cancer or advanced polyps (adenomas 10 mm in diameter, adenomas with 20% villous histologic characteristics, or any high-grade dysplasia regardless of size) (23). We classified patients with more than 1 lesion according to the most advanced lesion. We reexamined all advanced adenomas smaller than 10 mm to confirm their histologic diagnosis (24). Fecal Sampling Participants received an explanation of the test and written instructions on how to prepare the fecal samples. After voiding urine and flushing the toilet before having a bowel movement, participants placed a disposable paper float in the toilet bowl to immobilize the stool for easy sampling (Appendix Figure 1). Each fecal sample tube has a unique bar code. Before preparing the sample, the patient wrote his or her name and the date on the tube. The immunochemical FOBT sampling probe is inserted into an 8-cm2-cm test tubeshaped container. The patient inserts the probe into several different areas of the stool and then reinserts it firmly into the tube to seal it (Appendix Figure 2). The probe tip with the fecal sample is suspended in a standard volume of hemoglobin-stabilizing buffer. According to the manufacturers manual, the amount of stool obtained by this process is semistandardized (but does depend on fecal consistency) at 10 mg (SD, 0.5). According to the manufacturers data, the mean specimen size ranges from 9.03 mg (SD, 0.29) for diarrhea to 11.89 mg (SD, 0.76) for hard stools. Examinees prepared 3 daily or consecutive samples during the week before colonoscopy examination. They observed no dietary or medication restrictions other than stopping aspirin and anticoagulant therapy before endoscopy. Samples were stored in double ziplock bags at 4C until development within 2 weeks (20, 25). We processed the samples by using the OC-MICRO instrument (Eiken Chemical Co., Tokyo, Japan) as described in the Appendix. Appendix Figure 1. Folded paper float opened ( left ) and placed in toilet bowl ( right ). After defecation and fecal sampling, the participant flushes the float into the toilet. Appendix Figure 2. Stool probe and fecal sample storage tube. The patient removes the fecal probe that has a serrated tip that accumulates the fecal sample. The probe is then reinserted deeper into the tube past a scraper and through a membrane that removes excess feces. The bottom compartment of the tube contains a 2-mL buffer solution for stabilizing the fecal specimen in the tip serrations. For pricing the immunochemical FOBT at

Familial adenomatous polyposis

20, we used the local agents price for 3 tests and added administrative costs. In comparison, the authorized pricing (from Israels Ministry of Health) is

Germline mutations in BMPR1A/ALK3 cause a subset of cases of juvenile polyposis syndrome and of cowden and bannayan-riley-ruvalcaba syndromes

13 for screening with 3 guaiac-based FOBTs. The ethics committee of the Rabin Medical Center, Tel Aviv, Israel, approved the study in 2004. All participants gave written informed consent for the immunochemical FOBT and colonoscopy examination. Statistical Analysis We recorded each patients most severe pathologic finding (histologic characteristics, polyp size, and number of polyps) and the highest amount of fecal hemoglobin measured in that patients 3 immunochemical FOBT samples. We classified persons with only small rectal hyperplastic polyps as not having neoplasia. We analyzed fecal hemoglobin measurements according to the number of adenomas (<3 adenomas or 3 adenomas), lesion size, site in the colon (proximal or distal), and histology. We analyzed colorectal cancer and advanced adenoma separately and together as clinically significant colorectal neoplasia. Since the study sample was heterogeneous, we compared the sensitivity and specificity of the immunochemical FOBT in the 3 main categories of reason for referral (Appendix Table 1) by using the chi-square test and Fisher exact test. Appendix Table 1. Immunochemical Fecal Occult Blood Test and Endoscopy Results for Cancer or Clinically Significant Neoplasia, by Reasons for Colonoscopy* To classify a patients fecal hemoglobin level as normal or abnormal, we used 2 thresholds: the published and manufacturer-suggested threshold of 100 ng/mL of buffer and a threshold of 75 ng/mL, which we thought would give a higher sensitivity for detecting clinically significant neoplasia (14, 15, 20). We also repeated these analyses at different thresholds in increments of 25 ng/mL, ranging from 50 ng/mL to 200 ng/mL. We measured the diagnostic value of the immunochemical FOBT for detecting clinically significant neoplasia by using 5 criteria: sensitivity, specificity, likelihood ratios, and posttest probability after a negative and positive result. We compared sensitivity and specificity by using threshold values of 75 ng/mL or greater and 100 ng/mL or greater for abnormal findings and the McNemar test for symmetry. We reported polyp sizes and fecal hemoglobin measurements as means (SDs) and by quartiles. We also reported 95% CIs for means and likelihood ratios (26). Since the distribution of fecal hemoglobin measurements was not normally distributed, we used 1) a parametric test for log2-transformed data (since log of 0 is not defin

Isosorbide Dinitrate and Nifedipine Treatment of Achalasia: A Clinical, Manometric and Radionuclide Evaluation

Familial adenomatous polyposis (FAP) is characterized by the development of many tens to thousands of adenomas in the rectum and colon during the second decade of life. FAP has an incidence at birth of about 1/8,300, it manifests equally in both sexes, and accounts for less than 1% of colorectal cancer (CRC) cases. In the European Union, prevalence has been estimated at 1/11,300-37,600. Most patients are asymptomatic for years until the adenomas are large and numerous, and cause rectal bleeding or even anemia, or cancer develops. Generally, cancers start to develop a decade after the appearance of the polyps. Nonspecific symptoms may include constipation or diarrhea, abdominal pain, palpable abdominal masses and weight loss. FAP may present with some extraintestinal manifestations such as osteomas, dental abnormalities (unerupted teeth, congenital absence of one or more teeth, supernumerary teeth, dentigerous cysts and odontomas), congenital hypertrophy of the retinal pigment epithelium (CHRPE), desmoid tumors, and extracolonic cancers (thyroid, liver, bile ducts and central nervous system). A less aggressive variant of FAP, attenuated FAP (AFAP), is characterized by fewer colorectal adenomatous polyps (usually 10 to 100), later age of adenoma appearance and a lower cancer risk. Some lesions (skull and mandible osteomas, dental abnormalities, and fibromas on the scalp, shoulders, arms and back) are indicative of the Gardner variant of FAP. Classic FAP is inherited in an autosomal dominant manner and results from a germline mutation in the adenomatous polyposis (APC) gene. Most patients (~70%) have a family history of colorectal polyps and cancer. In a subset of individuals, a MUTYH mutation causes a recessively inherited polyposis condition, MUTYH-associated polyposis (MAP), which is characterized by a slightly increased risk of developing CRC and polyps/adenomas in both the upper and lower gastrointestinal tract. Diagnosis is based on a suggestive family history, clinical findings, and large bowel endoscopy or full colonoscopy. Whenever possible, the clinical diagnosis should be confirmed by genetic testing. When the APC mutation in the family has been identified, genetic testing of all first-degree relatives should be performed. Presymptomatic and prenatal (amniocentesis and chorionic villous sampling), and even preimplantation genetic testing is possible. Referral to a geneticist or genetic counselor is mandatory. Differential diagnoses include other disorders causing multiple polyps (such as Peutz-Jeghers syndrome, familial juvenile polyps or hyperplastic polyposis, hereditary mixed polyposis syndromes, and Lynch syndrome). Cancer prevention and maintaining a good quality of life are the main goals of management and regular and systematic follow-up and supportive care should be offered to all patients. By the late teens or early twenties, colorectal cancer prophylactic surgery is advocated. The recommended alternatives are total proctocolectomy and ileoanal pouch or ileorectal anastomosis for AFAP. Duodenal cancer and desmoids are the two main causes of mortality after total colectomy, they need to be identified early and treated. Upper endoscopy is necessary for surveillance to reduce the risk of ampullary and duodenal cancer. Patients with progressive tumors and unresectable disease may respond or stabilize with a combination of cytotoxic chemotherapy and surgery (when possible to perform). Adjunctive therapy with celecoxib has been approved by the US Food and Drug Administration and the European Medicines Agency in patients with FAP. Individuals with FAP carry a 100% risk of CRC; however, this risk is reduced significantly when patients enter a screening-treatment program.

Rectal cancer risk in hereditary nonpolyposis colorectal cancer after abdominal colectomy

Juvenile polyposis syndrome (JPS) is an inherited hamartomatous-polyposis syndrome with a risk for colon cancer. JPS is a clinical diagnosis by exclusion, and, before susceptibility genes were identified, JPS could easily be confused with other inherited hamartoma syndromes, such as Bannayan-Riley-Ruvalcaba syndrome (BRRS) and Cowden syndrome (CS). Germline mutations of MADH4 (SMAD4) have been described in a variable number of probands with JPS. A series of familial and isolated European probands without MADH4 mutations were analyzed for germline mutations in BMPR1A, a member of the transforming growth-factor beta-receptor superfamily, upstream from the SMAD pathway. Overall, 10 (38%) probands were found to have germline BMPR1A mutations, 8 of which resulted in truncated receptors and 2 of which resulted in missense alterations (C124R and C376Y). Almost all available component tumors from mutation-positive cases showed loss of heterozygosity (LOH) in the BMPR1A region, whereas those from mutation-negative cases did not. One proband with CS/CS-like phenotype was also found to have a germline BMPR1A missense mutation (A338D). Thus, germline BMPR1A mutations cause a significant proportion of cases of JPS and might define a small subset of cases of CS/BRRS with specific colonic phenotype.

Choice of fecal occult blood tests for colorectal cancer screening: recommendations based on performance characteristics in population studies: a WHO (World Health Organization) and OMED (World Organization for Digestive Endoscopy) report

The effects of sublingual isosorbide dinitrate (5 mg) and nifedipine (20 mg) were compared in 15 patients with achalasia. The parameters examined included the manometric measurement of the lower esophageal sphincter pressure, the radionuclide assessment of esophageal emptying and the clinical response. The mean basal lower esophageal sphincter pressure fell significantly after both drugs (p less than 0.01), with a maximum fall of 63.5% 10 min after receiving isosorbide dinitrate, but by only 46.7% 30 min after nifedipine. The esophageal radionuclide test meal retention was significantly less (p less than 0.01) only after receiving isosorbide dinitrate. The drug improved initial esophageal emptying by its effect on the lower esophageal sphincter and by relieving the test meal hold-up noted to occur at the junction of the upper and midesophagus. Eight patients cleared their test meal within 10 min after isosorbide dinitrate administration while only two did so after nifedipine. Subjectively, 13 patients had their dysphagia relieved by isosorbide dinitrate and 8 by nifedipine. However, this relief was not confirmed in 4 patients by the radionuclide study and they, as well as the other 3 patients who did not respond to therapy, were referred to pneumatic dilatation. Side effects were more prominent after nitrates. Three of the patients are currently receiving nifedipine and 5 patients received isosorbide dinitrate therapy for 8-14 mo. The radionuclide test meal is currently the best way of objectively evaluating drug therapy in patients with achalasia. Isosorbide dinitrate is more effective than nifedipine in relieving their symptoms.

Performance Characteristics and Evaluation of an Automated-Developed and Quantitative, Immunochemical, Fecal Occult Blood Screening Test

OBJECTIVE The authors analyzed the incidence of rectal cancer in patients with hereditary nonpolyposis colorectal cancer (HNPCC) after an abdominal colectomy. SUMMARY BACKGROUND DATA The treatment of choice for a newly diagnosed patient with HNPCC with colon cancer is an abdominal colectomy. The incidence of rectal cancer after abdominal colectomy in HNPCC is not known. MATERIALS AND METHODS A questionnaire was mailed to all International Collaborative Group on HNPCC members to identify patients in whom rectal cancer developed after total, subtotal or completion colectomy. Statistics were performed using the log-rank test, Kaplan-Meier method, and Coxs proportional hazards model. RESULTS Rectal cancer developed in 8 (11%) of 71 patients a median of 158 months (range, 38-282 months) from their primary procedure. Of these eight patients, adenomas in the rectal mucosa developed in five at risk either before (4) or synchronous (1) with the diagnosis of rectal cancer. At the time of diagnosis of rectal cancer, six of eight patients were being observed. Age at first procedure and whether the patient was under surveillance were the only significant variables (p < 0.05) in the multivariate analysis in terms of rectal cancer risk. The risk of developing rectal cancer was estimated to be 3% every 3 years after abdominal colectomy for the first 12 years. CONCLUSIONS The risk of rectal cancer in patients with HNPCC after an abdominal colectomy is approximately 12% at 12 years. Age at first surgical procedure and surveillance correlated with rectal cancer risk. Aggressive endoscopic surveillance of the rectum should be performed after abdominal colectomy.

Oral calcium suppresses increased rectal epithelial proliferation of persons at risk of colorectal cancer.

OBJECTIVE: There is now strong evidence that screening for colorectal cancer with fecal occult blood tests (FOBTs) is effective in reducing the incidence and mortality of this disease. Various FOBTs are now available with a wide range of evidence supporting their use. The purpose of this study was to review published data on the performance of these FOBTs to provide recommendations for their effective use in screening. METHODS: A joint committee representing the World Health Organization and the World Organization for Digestive Endoscopy was established for this study. A process was designed that would search the literature systematically for evidence of FOBT performance. Criteria for including studies in this paper were established based on study design, cohort size, and performance variables reported. RESULTS: Of the guaiac tests, Hemoccult SENSA had the highest sensitivity for cancer and adenomas but a high test positivity. It had a better readability than the older Hemoccult II test. Immunochemical tests, HemeSelect, FlexSure OBT, and Immudia Hem Sp have acceptable performance characteristics and are easier for participants to use but are more expensive. These tests have been well studied in large cohorts, but only Immudia Hem Sp is commercially available. CONCLUSIONS: At present, there is no extensively studied FOBT that fulfills the needs for all target populations worldwide. Choice of FOBT should take into account population dietary compliance and colonoscopy resources: The more sensitive newer tests should be used if dietary compliance is good (in the case of guaiac tests) and colonoscopy resources are adequate for diagnostic workup of people who test positive. Immunochemical tests remove the difficulties created by diet and drug restrictions and are more amenable to standardized development and quality control.

Family history of colorectal cancer as a marker of potential malignancy within a screening program

OBJECTIVES:Guaiac fecal occult blood colorectal cancer (CRC) screening tests (FOBT) are faulted for low sensitivity and nonspecificity for human hemoglobin (Hb). Automated-developed, immunochemical, human Hb FOBT (I-FOBT) is specific, eliminates diet restrictions, and Hb quantification allows selection of a threshold for colonoscopy. Aims were to determine 1) test reproducibility; 2) test stability; 3) intrapatient daily I-FOBT variation; 4) test sensitivity and specificity for neoplasia in 500 symptomatic/high-risk patients undergoing colonoscopy; and 5) to correlate fecal Hb measurements with findings.METHODS:The desktop instrument OC-Sensor (Eiken, Japan) automatically develops and quantitates 50 tests/h for Hb. Patients prepared three tests, which were quantified and then 1) repeatedly re-examined; 2) stored at 4°C or 20°C or 28°C and repeatedly examined; and 3) fecal Hb levels were correlated with colonoscopic findings.RESULTS:Five I-FOBTs re-examined five times in 1 day had no significant measurement changes. Thirty tests stored for 21 or more days had a decay/day of 0.3%± 0.4 at 4°C (NS), 2.2%± 1.7 at 20°C (NS), and 3.7%± 1.8 at 28°C (p < 0.05). There were intrapatient variations between the three daily I-FOBTs (NS). At the recommended 100 ng Hb/mL threshold, all six cases of CRCs and 20 out of 28 cases of advanced adenomas were detected; evaluated together their sensitivity and specificity were 76.5% and 95.3%.CONCLUSIONS:Desktop, automated-developed, quantitative I-FOBT is now available. Refrigerated OC-Sensor samples are stable for 21 days, easy to prepare and develop and, at the 100 ng Hb/mL threshold, have high sensitivity, specificity, and negative predictive values for significant neoplasia. Suitability for population CRC screening awaits further evaluation.

Analysis of genetic and phenotypic heterogeneity in juvenile polyposis

Dietary calcium may inhibit colonic carcinogenesis promoted by high fat, phosphate, and low fibre diets. In persons at risk for colon cancer oral calcium supplements significantly suppress increased rectal epithelial proliferation. This was studied in a cohort of 35 volunteers: 26 first degree relatives of colorectal cancer patients and nine who had had colonic adenomas (mean age 51.6 years, 17 (49%) men, all negative for large bowel neoplasia). 1.25-1.5 g elemental calcium was given in divided daily doses for three months. Rectal pinch biopsies were taken without bowel preparation, before and mean 8.4 weeks during and 7.2 weeks after treatment and incubated with tritiated thymidine. The mean number of labelled cells, as a ratio of the total number of crypt cells (labelling index-LI), and their crypt position, were determined. The mean number of labelled cells decreased during treatment by 29%, especially in the basal three-fifths of crypts. There was also a significant 10% increase in mean number of crypt cells during treatment. [Mean LI decreased by 36% (p less than 0.001) during calcium treatment and almost returned to basal values after cessation.] If a raised LI is a marker of potential malignancy and a randomised clinical trial confirms that calcium suppresses it, dietary intervention studies in high risk persons are indicated.