Negative Colonoscopy Results Research Articles

Small bowel tumors: What is the contribution of video capsule endoscopy?

Intestinal tumors represent less than 6% of digestive tumors and, because of the limitations of intestinal investigations, these tumors are difficult to diagnose. In this context, capsule endoscopy (CE) has proven effective especially in patients with obscure digestive bleeding. The aim of the present study was to calculate the frequency, and evaluate the diagnostic and therapeutic impact of CE in cases of small bowel tumors. A total of 95 patients (57 males and 38 females, mean age of 56 years) with negative endoscopy and colonoscopy results were directed to undergo CE examination. Of the 95 patients, 13 (13.7%) were diagnosed with small bowel tumors. The main indications for CE were obscure (occult and overt) gastrointestinal bleeding. The mean duration of symptoms before diagnosis was 10 months. The final histological diagnosis was established through surgery. In our patients, this included gastrointestinal stromal tumor (nine cases), adenocarcinoma (two cases) and carcinoid tumor (two cases). This study revealed that the prevalence of intestinal tumors appears to be higher than expected in patients through the use of CE.

Overuse of Screening Colonoscopy in the Medicare Population

All relevant authorities recommend an interval of 10 years between normal screening colonoscopies. We assessed the timing of repeated colonoscopies after a negative screening colonoscopy finding in a population-based sample of Medicare patients. A 5% national sample of Medicare enrollees from 2000 through 2008 was used to identify average-risk patients undergoing screening colonoscopy between 2001 and 2003. Colonoscopy was classified as a negative screening examination finding if no indication other than screening were in the claims and if no biopsy, fulguration, or polypectomy was performed. Time to repeated colonoscopy was calculated. Among 24,071 Medicare patients who had a negative screening colonoscopy finding in 2001 through 2003, 46.2% underwent a repeated examination in fewer than 7 years. In 42.5% of these patients (23.5% of the overall sample), there was no clear indication for the early repeated examination. In patients aged 75 to 79 years or 80 years or older at the time of the initial negative screening colonoscopy result, 45.6% and 32.9%, respectively, received a repeated examination within 7 years. In multivariable analyses, male sex, more comorbidities, and colonoscopy by a high-volume colonoscopist or in an office setting were associated with higher rates of early repeated colonoscopy without clear indication, while those 80 years or older had a reduced risk. There were also marked geographic variations, from less than 5% in some health referral regions to greater than 50% in others. A large proportion of Medicare patients who undergo screening colonoscopy do so more frequently than recommended. Current Medicare regulations intending to limit reimbursement for screening colonoscopy to every 10 years would not appear to be effective.

Diagnosis of Rectal Cancer by Electromagnetic Interactions

Although colonoscopy is effective in screening for colorectal cancer, its high cost and low compliance rates have encouraged a search for different methods. Our study was designed to evaluate the feasibility of rectal cancer detection using a nonlinear tuneable oscillator (TRIMprob), a recently developed device for detecting differences in electromagnetic properties of cancerous and normal tissues. We tested 228 patients (115 male and 113 female) between March and September 2006: 114 patients with rectal cancer diagnosed on colonoscopy and 114 patients with negative colonoscopy results. The TRIMprob probe was moved over the surface of the pelvic area from the back and the front, with the patient standing, normally dressed, between the operator and the system receiver. The signal variation of three spectral lines, for 465-MHz, 930-MHz, and 1395-MHz frequencies was recorded for each of six probe positions. Analysis of resonance values showed that only the 465-MHz frequency differentiated patients with rectal cancer from those without cancer at all six probe positions (P < 0.001). With a cutoff value of 50 arbitrary units, the area under the receiver operating characteristic curve was 0.94 (specificity, 85 percent; sensitivity, 94 percent). The TRIMprob test discriminates well between patients with normal rectal tissue and those with malignant lesions. These preliminary results confirm that electromagnetic detection of rectal cancer is possible and suggest this method of extracorporeal scanning may be useful as a first-level screening tool.

Study supports 20-year interval for colonoscopy screening

Patients with a negative colonoscopy result might not need to have another colonoscopy for 20 years or more, suggests a population-based, case–control study (Gut 2006; 55: 1145–50). Hermann Brenner and colleagues (German Cancer Research Centre, Heidelberg, Germany) compared the adjusted relative risks of colorectal cancer in 380 patients who had a previous negative colonoscopy with those in 485 control patients who had not undergone previous colonoscopy, according to time since colonoscopy. Patients with previous negative colonoscopy had a 74% lower risk of colorectal cancer than did those without previous colonoscopy (adjusted odds ratio 0·26; 95% CI 0·16–0·40). The risk remained low even when the colonoscopy had been done 20 or more years previously, Brenner and colleagues report. “These fi ndings should have an impact on future screening guidelines”, says Brenner. “There are virtually no data available on colorectal-cancer risk beyond 10 years after a negative screening colonoscopy, which has hindered recommendations of longer screening intervals.” According to John Marshall (Georgetown University, Washington, DC, USA), this study suggests that patients who have even one negative colonoscopy at some point in their lives have a low risk of developing colon cancer and that this conclusion seems justifi ed by the data. However, he cautions that only fi ve (1%) patients and 13 (3%) controls fell into the “over 20-year” category, on which researchers base part of their conclusions. “We must remember that the majority of patients diagnosed with colon cancer have later-stage disease, suggesting that we are failing to detect earlystage colon cancer in most patients”, says Marshall. “While one colonoscopy is better than none, one should not conclude from this study that one, and only one, colonoscopy will prevent colon-cancer deaths.”