The Asia-Pacific Colorectal Screening (APCS) scoring system, combined with a stool DNA test, could improve the detection of advanced colorectal neoplasms and limit colonoscopy use, according to a new study published in Clinical Gastroenterology and Hepatology.
Although a colonoscopy can detect both colorectal cancer and precancerous lesions, using it as the primary screening tool can cause barriers due to high costs, limited resources, and low compliance, wrote Junfeng Xu of the gastroenterology department at the First Medical Center of Chinese PLA General Hospital, Beijing, and colleagues.
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“Therefore, a more efficient risk-adapted screening approach for selection of colonoscopy is recommended,” the authors wrote. “This APCS-based algorithm for triaging subjects can significantly reduce the colonoscopy workload by half.”
Colorectal cancer is the third most common cancer worldwide, and in China, it was the third most diagnosed cancer and fourth most common cause of cancer-related death in 2016. In countries with limited health care resources, risk-adapted screening strategies could be more cost-effective and accessible than traditional screening strategies, the authors wrote.
Developed by the Asia-Pacific Working Group on CRC, the APCS score is based on age, sex, smoking status, and family history of colorectal cancer. Those with a score of 0-1 are considered low-risk, while scores of 2-3 are considered moderate-risk, and scores of 4-7 are considered high-risk.
In a cross-sectional, multicenter observational study, the investigators calculated APCS scores for 2,439 participants who visited eight outpatient clinics or cancer screening centers across four provinces in China between August 2017 and April 2019. Colonoscopy appointments were scheduled for all participants.
Participants provided test results for a stool DNA test (SDC2 and SFRP2 tests) and fecal immunochemical test (FIT), with colonoscopy outcomes used as the gold standard. The researchers used the manufacturer’s recommended hemoglobin threshold of 20 μg/g of dry stool for a positive result on FIT, in addition to a threshold of 4.4 μg/g to match the specificity of the stool DNA test.
Among all participants, 42 patients (1.9%) had colorectal cancer, 302 patients (13.5%) had advanced adenoma, and 551 patients (24.6%) had nonadvanced adenoma on colonoscopy.
Based on the APCS score, 946 participants (38.8%) were categorized as high risk, and they had a 1.8-fold increase in risk for advanced neoplasms (95% confidence interval, 1.4-2.3), as compared with the low- and moderate-risk groups.
Compared with direct colonoscopy, the combination of APCS score and stool DNA test detected 95.2% of invasive cancers (among 40 out of 42 patients) and 73.5% of advanced neoplasms (among 253 of 344 patients). The colonoscopy workload was 47.1% with this strategy. The risk-adapted screening approach required significantly fewer colonoscopies for detecting one advanced neoplasm than a direct colonoscopy screening, at 4.17 versus 6.51 (P < .001).
“Our findings provide critical references for designing effective population-based CRC screening strategies in the future, especially in resource-constrained countries and regions,” the authors concluded.
Avoiding complications
“Colonoscopy is expensive and time consuming for both the patient and the health care system. Colonoscopy is also not without risk since bowel perforation, post-procedural bleeding, and sedation-related complications all occur at low but measurable rates,” said Reid Ness, MD, associate professor of medicine and gastroenterologist at Vanderbilt University Medical Center, Nashville, Tenn.
Dr. Reid M. Ness
“The primary strength of the study was that all patients eventually received colonoscopy, allowing for the best estimate of strategy sensitivity for advanced colorectal neoplasia,” he said.
At the same time, the cross-sectional study was unable to estimate the benefit of using this type of screening strategy over time, Dr. Ness said. With limited endoscopic resources available in many countries, however, clinicians need better modalities and strategies for noninvasive identification of advanced colorectal neoplasia, he added.
“Since less than 5% of the population will eventually develop colorectal cancer, the overwhelming majority can only be discomfited and possibly injured through colonoscopy screening,” he said. “For these reasons, the use of a CRC screening strategy that minimizes the use of colonoscopy without compromising the identification rate for advanced colorectal neoplasia is best for both the patient and the health care system.”
The study was supported by grants from the Beijing Municipal Science and Technology Commission. The authors declared no conflicts of interest. Dr. Ness reported no relevant disclosures.
This article was updated Oct. 4, 2022.