Adenoma Detection Rate: Raising The Bar in Colorectal Cancer Detection
by ColoWrap, on June 29, 2022
Did you know that colorectal cancer is the third leading cause of cancer death for both men and women, with an estimated 52,580 colorectal cancer related deaths in the US in 2022? Thankfully, there are multiple options for early cancer detection that can make all the difference in stopping the disease at its source.
One such option for early detection is Colonoscopy. Colonoscopy is an endoscopic procedure in which a colonoscopist inserts a long, thin tube with a small camera at the tip into the colon for observation and small procedures. Colonoscopy is considered to be the gold standard for colon cancer screening. This is because a colonoscopy gives doctors the opportunity to remove precancerous polyps, called adenomas, before they have the chance to possibly develop into colorectal cancer.
Despite being performed for over 40 years, only in the past 15 years has attention really been drawn to the quality of colonoscopy and its success in colorectal cancer prevention. Patient outcomes are largely dependent on the skill and competence of the colonoscopist, and colonoscopists' techniques often vary widely in response to both normal and abnormal findings. With this in mind, the U.S. Multisociety Task Force on Colorectal Cancer came together in 2002 to propose quality indicators, specifically the Adenoma Detection Rate (ADR), that colonoscopists can use to measure how effectively and safely they perform the procedure.
What is Adenoma Detection Rate?
To put it simply, a colonscopist’s adenoma detection rate is the percentage of patients aged 50 (and now 45) and older undergoing colonoscopy who have one or more adenomas detected during the procedure.
Adenomas are precancerous polyps that grow in the inner lining of the colon or rectum. Polyps come in a variety of shapes and sizes but tend to either be flat (sessile) or on a stalk (pedunculated). Over time, and if left untreated, adenomas can develop into colorectal cancer which is why early cancer detection via colonoscopy is essential to overall health and wellness.
How is Adenoma Detection Rate Calculated?
The Adenoma Detection Rate is the measurement that best reflects how carefully colonoscopy is performed. A colonscopist’s ADR is determined by a simple calculation:
(Number of Examinations with Adenomas / Total Number of Examinations) x 100
What is a Good Adenoma Detection Rate?
The American College of Gastroenterology states that a colonscopist’s Adenoma Detection Rate should be at least 25% in men and 15% in women. Along with ADR, a colonscopist’s average withdrawal time is an important secondary measure of thorough examination; the national average is at least six minutes.
However, these ADR and withdrawal rates are just the minimum threshold, and many in the gastroenterology field are calling for standards to be raised. A study of over 300,000 colonoscopies performed by 136 gastroenterologists reported that for each 1.0% increase in ADR, the risk for interval colon cancer is reduced by 3% and the risk for colorectal-related deaths is reduced by 5%.
Experts across the field agree that the ideal ADR should be somewhere between 45-50%, a significant increase from the current standard of 20%. So the question remains: what’s keeping colonoscopists' ADRs lower than ideal, and what can be done to overcome these obstacles?
What Affects Adenoma Detection?
Most research shows that longer withdrawal time is associated with higher adenoma detection rates. A colonscopist’s withdrawal time refers to how quickly the colonoscope is removed once the scope reaches the cecum—the farthest point in the colon. A 2018 study found significantly higher ADR rates when withdrawal time in the colon was greater than three minutes.
When the colonoscopist is able to take their time and withdraw the colonoscope slowly, the likelihood of polyps going undetected is considerably reduced. A slower withdrawal gives the endoscopist additional time to examine the colon which naturally improves the chances of finding precancerous polyps that may be missed in a hastier examination.
However, slow and steady is not the way when it comes to cecal insertion time. Studies show that longer cecal intubation times—the time from rectum insertion to the time when the cecum is visible—are associated with lower adenoma detection rates, which in turn increases the risk of colorectal cancer-related death.
This inverse relationship is possibly a reflection of the endoscopist’s technical skills. An experienced physician is more likely to be able to insert the colonoscope in a timely manner, and will typically perform a more accurate exam.
However, colonoscopy can be a tricky procedure due to the constant movement of the colon and anatomical variability each patient’s body habitus presents. Even the most experienced and technically proficient colonoscopists struggle with the complications that arise from a phenomenon called looping.
Looping occurs when the colonoscope stretches and distends the colon in response to the physician’s efforts to advance the scope forward. Once a loop forms, the procedure often cannot continue until the colon is splinted, which is typically done by applying manual abdominal pressure.
The stop-and-go nature of addressing looping means that colonoscopists are more likely to suffer from physical or mental fatigue, and they may even speed up the withdrawal to counteract demanding insertions. Even worse, colonoscopists may forgo correcting looping during insertion and try to withdraw the colonoscope through a loop, which compromises scope control and can result in several inches of the colon going uninspected. This results in more missed polyps, a lower ADR, and an overall increased risk in colorectal cancer.
Technologies That Can Help ADR:
Significant efforts are underway to help physicians boost their adenoma detection rates and improve early cancer detection. Recent trials indicate that endoscopists working with an artificial intelligence (AI) system have achieved improved detection rate of polyps. Additionally, closer attention is now being paid to the quality of the patient’s bowel preparation and its impact on overall procedure success.
However, proper bowel preparation can only do so much when it comes to preventing looping and AI technologies still have a long way to go before they can be trusted as a standard of care.
Colorectal cancer is projected to cause roughly 52,580 deaths in the next year alone. There is simply no time to waste when it comes to improving adenoma detection rates in colonoscopy, and ColoWrap is perfectly poised to do just that.
ColoWrap is an anti-looping colonoscopy compression device that decreases cecal intubation time, and reduces the need for labor-intensive manual pressure and patient repositioning. By reducing the cecal intubation time, ColoWrap allows physicians to better focus their attention on the exam, which in turn improves polyp detection and overall adenoma detection rates. A focused colonoscopist is an accurate one, and that can make all the difference when it comes to early cancer detection.