Ultrasound, CT and colonoscopy of colonic cancer. Sensitivity and specificity of a stool DNA multitarget assay panel for the detection of advanced colorectal neoplasia. A comparison of virtual and conventional colonoscopy for the detection of colorectal polyps. Prospective evaluation of ultrasound in distal ileal and colonic obstruction. Fecal DNA versus fecal occult blood for colorectal-cancer screening in an average-risk population. Diagnosis and staging of colonic tumors by conventional abdominal sonography as compared with hydrocolonic sonography.
Barium enema and colonoscopy are commonly used for the investigation of suspected colonic cancer . These techniques are relatively invasive and both the investigation and the preceding bowel preparation are dem and ing , particularly in the elderly . A prospect i ve , blinded trial was conducted to compare ultrasound ( US ) and CT with colonoscopy . CT and colonoscopy were performed on 50 patients with symptoms suggesting colonic cancer . Both radiological investigations were performed prior to the bowel preparation for colonoscopy . US was performed without any preparation and oral contrast medium was the only preparation used for CT . Colonoscopy detected six cancers , all of which were diagnosed by both US and CT . In addition , US and CT diagnosed a further cancer not seen on colonoscopy due to an incomplete study . US had a sensitivity and specificity of 100 % and CT a sensitivity of 100 % and a specificity of 84 % . US and CT were poor at diagnosing polyps . If the detection of polyps greater than 2 cm is included then US sensitivity falls to 67 % and CT sensitivity falls to 89 % and specificity rises to 88 % . In conclusion , both US and CT are possible alternatives to colonoscopy in the investigation of symptomatic patients with suspected colonic cancer . The use of these techniques could markedly reduce the need for colonoscopy  in this patient population with attendant cost savings . Non-invasive imaging has particular advantages in the elderly who cope poorly with both the bowel preparation and the procedure Colorectal cancer is the second-leading cause of cancer death . New noninvasive options for screening capable of diagnosing cancer at an early stage are needed to improve compliance and reduce mortality . This study was design ed to provide an estimate of the sensitivity and specificity of a multitarget assay panel ( MTAP ) of stool DNA changes .  Eighty patients with advanced colorectal neoplasia and 212 control subjects provided stool sample s before colonoscopy . Patients with hereditary colorectal cancer syndromes were excluded . The MTAP included 21 specific mutations in the adenomatous polyposis coli ( APC ) , p53 , and K-ras genes , a microsatellite instability marker ( BAT-26 ) , and a marker of abnormal apoptosis ( DNA Integrity Assay ) . All sample s were analyzed in the clinical laboratory at EXACT Sciences . Multitarget assay panel detected 33 of 52 patients ( 63.5 % , 95 % confidence interval [ CI ] , 49.0%-76.4 % ) with invasive colorectal cancer , including 26 of 36 ( 72.2 % ) with node-negative disease ( American Joint Committee on Cancer [ AJCC ] stage I/II ) and 7 of 16 ( 43.7 % ) with advanced disease ( AJCC stage III/IV ) . Sixteen of 28 patients ( 57.1 % ; 95 % CI , 37.2%-75.5 % ) with advanced adenomas ( lesions containing high- grade dysplasia , villous adenomas , or tubular adenomas > 1 cm in size ) were detected , including 6 of 7 ( 85.7 % ) with high- grade dysplasia and 10 of 21 ( 47.6 % ) with other advanced adenomas . Specificity was 96.2 % ( 95 % CI , 92.7%-98.4 % ) in patients with either no colorectal lesions or diminutive polyps . Multitarget assay panel has better sensitivity than that reported with use of Hemoccult(R ) II in fecal occult blood testing , with similar specificity . Sensitivity appeared to be equally high for patients with node-negative and advanced disease , as well as for advanced adenomas . This study contained a disproportionately high number of distal cancers and , as such , may not be representative of results in proximal lesions . Although a prospect i ve study in an average-risk population is needed to vali date these findings , MTAP may offer an important noninvasive option for population -based screening BACKGROUND Virtual colonoscopy is a new method of imaging the colon in which thin-section , helical computed tomography ( CT ) is used to generate high-resolution , two-dimensional axial images . Three-dimensional images of the colon simulating those obtained with conventional colonoscopy are then reconstructed off-line . We compared the performance of virtual and conventional colonoscopy for the detection of colorectal polyps . METHODS We prospect ively studied 100 patients at high risk for colorectal neoplasia ( 60 men and 40 women ; mean age , 62 years ) . We performed virtual colonoscopy immediately before conventional colonoscopy . We inserted a rectal tube and insufflated the colon with air to the maximal level that the patient could tolerate . We administered 1 mg of glucagon intravenously immediately before CT scanning to minimize the degree of smooth-muscle spasm and peristalsis and to reduce the patient 's discomfort . RESULTS The entire colon was clearly seen by virtual colonoscopy in 87 patients and by conventional colonoscopy in 89 . Fifty-one patients had normal findings on conventional colonoscopy .  In the other 49 , we identified a total of 115 polyps and 3 carcinomas . Virtual colonoscopy identified all 3 cancers , 20 of 22 polyps that were 10 mm or more in diameter ( 91 percent ) , 33 of 40 that were 6 to 9 mm ( 82 percent ) , and 29 of 53 that were 5 mm or smaller ( 55 percent ) . There were 19 false positive findings of polyps and no false positive findings of cancer . Of the 69 adenomatous polyps , 46 of the 51 that were 6 mm or more in diameter ( 90 percent ) and 12 of the 18 that were 5 mm or smaller ( 67 percent ) were correctly identified by virtual colonoscopy . Although discomfort was not specifically recorded , none of the patients requested that virtual colonoscopy be stopped because of discomfort or pain . CONCLUSIONS In a group of patients at high risk for colorectal neoplasia , virtual and conventional colonoscopy had similar efficacy for the detection of polyps that were 6 mm or more in diameter AIM To evaluate prospect ively the usefulness of ultrasound in determining the site and cause of distal small bowel and colonic obstruction . MATERIAL S AND METHODS Ultrasound findings in 60 consecutive patients with suspected distal ileal or colonic obstruction were correlated with final surgical and radiological diagnoses . The diagnostic value of ultrasound was compared with plain abdominal radiography ( AXR ) for the presence and level of obstruction . RESULTS Forty-five patients were confirmed to be obstructed .  Ultrasound  correctly identified obstruction in 44/45 and the cause in 36/45 ( 80 % ) . Overall sensitivity of US for obstruction was 98 % and specificity 80 % , compared with 79 % and 53 % respectively for the AXR . CONCLUSION Ultrasound is useful in determining the presence and cause of distal ileal and colonic obstruction BACKGROUND Although fecal occult-blood testing is the only available noninvasive screening method that reduces the risk of death from colorectal cancer , it has limited sensitivity . We compared an approach that identifies abnormal DNA in stool sample s with the Hemoccult II fecal occult-blood test in average-risk , asymptomatic persons 50 years of age or older . METHODS Eligible subjects su bmi tted one stool specimen for DNA analysis  , underwent st and ard Hemoccult II testing , and then underwent colonoscopy . Of 5486 subjects enrolled , 4404 completed all aspects of the study . A subgroup of 2507 subjects was analyzed , including all those with a diagnosis of invasive adenocarcinoma or advanced adenoma plus r and omly chosen subjects with no polyps or minor polyps . The fecal DNA panel consisted of 21 mutations . RESULTS The fecal DNA panel detected 16 of 31 invasive cancers , whereas Hemoccult II identified 4 of 31 ( 51.6 percent vs. 12.9 percent , P=0.003 ) . The DNA panel detected 29 of 71 invasive cancers plus adenomas with high- grade dysplasia , whereas Hemoccult II identified 10 of 71 ( 40.8 percent vs. 14.1 percent , P<0.001 ) . Among 418 subjects with advanced neoplasia ( defined as a tubular adenoma at least 1 cm in diameter , a polyp with a villous histologic appearance , a polyp with high- grade dysplasia , or cancer ) , the DNA panel was positive in 76 ( 18.2 percent ) , whereas Hemoccult II was positive in 45 ( 10.8 percent ) . Specificity in subjects with negative findings on colonoscopy was 94.4 percent for the fecal DNA panel and 95.2 percent for Hemoccult II . CONCLUSIONS Although the majority of neoplastic lesions identified by colonoscopy were not detected by either noninvasive test , the multitarget analysis of fecal DNA detected a greater proportion of important colorectal neoplasia than did Hemoccult II without compromising specificity BACKGROUND Ultrasonic examination has become increasingly important in the diagnosis of diseases of the gastrointestinal tract . In neoplastic diseases of the large intestine , however , the diagnostic value of conventional transabdominal sonography is limited . The purpose of this investigation was to determine whether the evaluation and staging of colonic tumors would be improved by the retro grade instillation of water into the colon in a procedure called hydrocolonic sonography . METHODS Three hundred patients were examined in a prospect i ve study in which both conventional transabdominal sonography and transabdominal hydrocolonic sonography were performed before the diagnosis was verified by colonoscopy . The indication for the examinations was abdominal pain , diarrhea , weight loss , or the presence of occult blood in a stool specimen . RESULTS With the instillation of water into the colon , it was possible to display the colon sonographically from the rectosigmoid transition to the cecum in 97 percent of the patients examined . In addition to permitting the evaluation of the colonic lumen , the procedure allowed the five layers of the colonic wall and the connective tissue surrounding the colon to be examined in detail . Only 9 of 29 carcinomas were diagnosed by conventional abdominal sonography ( 31 percent ) , whereas hydrocolonic sonography permitted the diagnosis of 28 ( 97 percent ) . No polyps could be detected by conventional abdominal sonography , whereas hydrocolonic sonography permitted the diagnosis of 38 of 42 polyps greater than or equal to 7 mm ( 91 percent ) and 3 of 12 polyps less than 7 mm ( 25 percent ) . In addition , detailed evaluation of the structure of the bowel wall with hydrocolonic sonography permitted a more precise staging of colonic tumors . CONCLUSIONS Hydrocolonic sonography , a new diagnostic procedure , can facilitate the diagnosis and staging of colonic tumors
In these tumors , mortality data do not reflect the true incidence of this disease , since survival has improved in recent years , particularly in younger individuals .
In contrast to other European countries , Spain ranks in an intermediate position in terms of CRC-related incidence and mortality .
This risk clearly increases with age , with a notorious rise in incidence from 50 years of age on .
Survival following CRC detection and management greatly depends upon tumor stage at the time of diagnosis ; hence the importance of early detection and –because of their malignant potential– of the recognition and excision of colorectal adenomas .
Thus , polypectomy and then surveillance are the primary cornerstones in the prevention of CRC ( 1 - 4 ) .
For primary prevention , fiber-rich diets , physical exercising , and the avoidance of overweight , smoking , and alcohol have been recommended .
Low-dose NSAIDs or ASA are still not recommended for the prevention of CRC as of today ( 1 ) .
CRC develops through well-established stages from lesions in colonic gl and crypts to adenomas to cancer .
The adenoma-carcinoma sequence is characterized by cumulative mutations in both suppressor genes and oncogenes , which affect the balance between cell proliferation and apoptosis ; thus , each mutational event confers tumor cells with a growth advantage entailing a clonal expansion along multiple stages , and ultimately tumor progression ( 5 ) .
From all the above , CRC screening is warranted : a ) this tumor has a high incidence and results in severe morbidity and mortality ; b ) the premalignant potential of colorectal adenomas is well known ; c ) the tumor may be detected using highly sensitive endoscopic techniques ; and d ) early management improves survival .
The population with a moderate risk for CRC includes individuals older than 50 years with no additional risk factors ( family members with CRC or adenomas , chronic inflammatory bowel disease ) .
The most cost-effective screening option for each population area or country remains to be established , as well as as its financial impact on healthcare systems ( 7 - 9 ) .