Procedure setting, technique and cost are key for effective colorectal cancer screening


CHICAGO, IL (May 17, 2005) – Current guidelines recommend that anyone over the age of 50 years be screened for colorectal cancer (CRC) using one of the standard available technologies, including colonoscopy, flexible sigmoidoscopy, air contrast barium enema and fecal occult blood testing. Research presented today at Digestive Disease Week® 2005 (DDW) evaluates the accuracy rates and cost benefits of various screening procedures. DDW is the largest international gathering of physicians, researchers and academics in the fields of gastroenterology, hepatology, endoscopy and gastrointestinal surgery.

"Colorectal cancer screening is essential in the diagnosis and prevention of colon cancer, a common and often preventable cancer," said Robert Bresalier, M.D., of the University of Texas MD Anderson Cancer Center. "Finding screening procedures that are not only accurate, but cost effective will help ensure proper patient diagnosis while alleviating stress on patient and physician pocketbooks."

Cost Effectiveness Of Imaging Tests and Surveillance Strategies for Colorectal Cancer (Abstract 91)

When screening for colorectal cancer, one of the primary concerns is accuracy. But with multiple new technological options available to patients today, cost effectiveness is also an important consideration. In this study by researchers at Duke University, types of colon screening procedures were compared for both accuracy and cost.

In a previous trial, computed tomographic colonography (CTC) was tested as a potential alternative to colonoscopy for patients at risk for colorectal cancer, evaluating the sensitivity of air contrast barium enema (ACBE), CTC and colonoscopy. For this study, the team evaluated the cost effectiveness of the three imaging tests as potential monitoring strategies in this population.

The researchers developed a model to evaluate the costs and health benefits for investigation of the colon. Patients were initially examined with one of three tests: colonoscopy, ACBE or CTC. Based on the results of the tests, patients were treated or monitored according to current standards. The sensitivity of colonoscopy, ACBE and CTC tests was 98 percent, 48 percent and 59 percent for large lesions (= or > than 10 millimeters), respectively.

Results showed that the ACBE was the least costly procedure, but had the lowest quality-adjusted life expectancy rate. CTC, the most expensive procedure, cost an incremental $1,100 but was slightly more accurate than the ACBE. Colonoscopy was the most accurate and was less expensive than CTC.

"This study confirms that standard colonoscopy is still the best and most cost-effective option for an accurate diagnosis of colon cancer, based on the technologies that are currently available," said Don Rockey, M.D., of Duke University and senior author of the study. "However, because CTC technologies are rapidly evolving, we plan to update our analysis as significant technological advances are achieved."

Predictors of Missed Colorectal Cancer During Colonoscopy: A Population-Based Analysis (Abstract SP751)

Colorectal cancer is the second leading cause of cancer-related deaths in the United States, thus CRC screening has become one of the most recommended procedures for people age 50 and older. However, research suggests that the miss rate for colorectal cancer during colonoscopies can be between two and six percent, depending on the site of the tumor. Researchers from the University of Toronto found specific predictors, including a patient's age, gender, location of tumor and having a colonoscopy in an office-based setting, which may help explain the missed colorectal cancers.

Using Canadian institutional data records, the team identified all individuals over the age of 20 years with a new diagnosis of right-sided CRC, transverse (arch of the colon) CRC and rectal/sigmoid (the junction between the colon and rectum) CRC, in Ontario from 1997 to 2002. A total of 12,839 patients were analyzed in the study cohort, 3,060 with right-sided CRC, 945 with transverse CRC and 8,834 with rectal/sigmoid CRC. The proportions of missed cancers were: 190 patients (6.2 percent) with right-sided CRC, 41 patients (4.3 percent) with transverse CRC and 182 patients (2.1 percent) with rectal/sigmoid CRC.

The team found the following circumstances independently increased the rate of missed diagnoses: Older age, being female, history of previous abdominal/pelvic surgery, history of diverticulosis, right-sided or transverse CRC, a colonoscopy performed by an internist or family physician, and having an office-based colonoscopy.

"Missed diagnoses of colon cancer are of major concern, and while some of these factors are unavoidable, others can be resolved to ensure more accuracy in detecting colorectal cancer," said Brian Bressler, M.D., of the University of Toronto and lead author of the study. "This study will help in the development of appropriate procedural standards and new technologies that take into account the factors that often lead to missed diagnoses."

Variation in Adenoma Detection Rates and Colonoscopic Withdrawal Times During Screening Colonoscopy (Abstract SP752)

While reviewing the accuracy and value of standard colonoscopy as a screening procedure, researchers at Rockford Gastroenterology Associates found significant differences in the detection of cancerous polyps among gastroenterologists in their clinical practice.

The study population consisted of 2,051 subjects who underwent colonoscopy for colorectal cancer screening in a community-based GI practice. Approximately 90 percent of the screening subjects had no family history of colon cancer. Colonoscopy was performed by one of 12 experienced, board-certified gastroenterologists, all of whom had completed more than 1,000 colonoscopies. All clinicians used similar equipment in an ambulatory surgery center.

The median detection rate of adenomas--potentially pre-cancerous polyps--was 25.2 percent among the screened subjects. The investigators noted lower than average polyp detection rates among clinicians with shorter than average procedural withdrawal times (average of seven minutes). Moreover, the pooled detection rates for "advanced lesions" -- those 10 mm or more in size or with microscopic changes that may confer a greater risk for malignancy -- was 6.6 percent for endoscopists with a slower than average withdrawal time, compared to 2.4 percent for those with a faster than average withdrawal time.

"These data highlight the importance of endoscopic technique during screening colonoscopy, which could impact significantly on the overall effectiveness of this procedure in reducing rates of colorectal cancer," said Robert Barclay, M.D., of Rockford Gastroenterology Associates and lead author of the study.

Source: Eurekalert & others

Last reviewed: By John M. Grohol, Psy.D. on 21 Feb 2009
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