Colorectal cancer screening and prevention

In August 2024, the American Society for Gastrointestinal Endoscopy (ASGE) and the American College of Gastroenterology (ACG) published an update on quality indicators for colonoscopy to ensure that the highest standards are met for performing colonoscopy.¹ That same month, the American Cancer Society (ACS) and Color Health launched a new pilot program that provides free at-home colorectal cancer screening kits to people in underserved and rural areas.²

Both ventures attempt to address ongoing gaps in colorectal cancer screening: one by continuing to focus on the optimal performance of colonoscopy to ensure its preventive potential and the other by broadening accessibility to screening in communities where access remains a barrier.

First issued in 2006 and again in 2015, the ACG/ASGE guidelines on quality indicators for colonoscopy provide a framework for quality improvement efforts that endoscopists or endoscopy units can use to improve their technical performance of a colonoscopy. The guidelines offer comprehensive or general colonoscopy indicators broken down into three periods (pre-, intra-, and postprocedural indicators), with each quality indicator classified as an outcome or process measure based on current evidence.

Emphasized in the updated guidelines, as in the 2015 guidelines, are what the authors call “priority indicators”—those indicators seen as the most clinically relevant and related to key colonoscopy outcomes. It is recommended that all endoscopists and endoscopy units measure these indicators, according to the lead author of the guidelines, Douglas K. Rex, MD, director of endoscopy at Indiana University Hospital in Indianapolis.

The identified priority quality indicators include the (1) adenoma detection rate, (2) sessile serrated lesion detection rate (a new priority indicator), (3) rate of using recommended screening and surveillance intervals, (4) bowel preparation adequacy rate (a new priority indicator), and (5) cecal intubation rate (which can be measured intermittently or not at all after consistent high-level performance has been demonstrated).

Dr Rex says that the inclusion of the sessile serrated lesion detection rate as a priority indicator may be new to some oncologists, but it reflects new evidence showing that although an important subset of colonoscopists adequately detect conventional adenomas, their detection of sessile serrated lesions is suboptimal. Detection of both types of lesions is critical to screening because colorectal cancer develops through both of these two pathways: the adenoma–carcinoma sequence and the serrated polyp–carcinoma sequence. “Cancers arising through these two pathways can typically be distinguished by their molecular features,” he says.

“It is now recommended that all colonoscopists measure their detection of both types of precancerous lesions,” he says.

Underlying the emphasis on priority indicators, says Dr Rex, is the need to help all endoscopists and endoscopy units to implement the most important quality measures when limited budgets may disallow implementation of all indicators. The overall goal is to “reduce operator dependence and maximize the cancer prevention potential and safety of colonoscopy,” he says.

Commenting on the guidelines, Virginia O. Shaffer, MD, professor of surgery and chief of the Section of Colon and Rectal Surgery at UChicago Medicine, underscores the extreme importance of the quality indicators “so that we are providing the same standard of care across the country no matter where a patient lives.”

Providing the same standard of care also may mean ensuring that everyone is aware of the importance of screening and that they have access to screening. Dr Shaffer cites both lack of awareness and social and economic factors as key barriers to screening.

The pilot program by the ACS and Color Health is an attempt at broadening screening by offering a free and often preferred alternative to colonoscopy, particularly in under-resourced and rural communities where social determinants of health may impede access.

The recently launched program is offering free at-home fecal immunochemical testing (FIT) kits to participating federally qualified health centers (FQHCs), local libraries, and community centers for distribution to eligible people aged 45–75 years who are at average risk for colorectal cancer. The program can be accessed at https://www.color.com/cust/freescreening.

“This program offers an additional avenue for accessing screenings, facilitating early intervention for colorectal cancer among populations who, without this option, may not get screened at all,” says Rebecca Miksad, MD, MPH, a medical oncologist and head of the first High-Risk Cancer Genetics Clinic at the Boston University School of Medicine and chief medical officer at Color Health. “Additionally, we aim to improve screening rates in historically underrepresented populations, particularly within FQHCs.”

Recommended by the ACS as an alternative screening tool, annual FIT has a 75% sensitivity for detecting colorectal cancer, and its overall performance is considered similar to that of other options by many expert groups, according to Dr Miksad. It is also less invasive and often is preferred by patients because of its convenience, she says.

The test is intended for people at average risk for colorectal cancer. She cautions, however, that FIT does not replace the need for colonoscopies for those at increased risk, including some people with previously detected polyps and those with a family history of, or a genetic predisposition to, colorectal cancer.

All patients who complete and submit a FIT test receive a follow-up review of their results so that they can discuss any necessary next steps, such as a diagnostic colonoscopy, for those with abnormal test results.

Dr Shaffer underscores the importance of a follow-up colonoscopy as needed. “Free at-home colorectal cancer screening kits are a good first step, but we must not stop there,” she says. “If a screening test is positive, we need to have a seamless plan for the next step, which is a colonoscopy.”

Dr Miksad cites data from a large colorectal cancer screening program at Kaiser Permanente in Northern California in which FIT kits were mailed to eligible members to increase screening participation. After 1 year of implementation, the percentage of eligible members who were up to date on screening went from 40% to 82%. Key components of the program included automated outreach (e.g., pre-letters, FIT kits, automated calls, and reminder postcards) and personalized telephone outreach and reminders during clinic visits (which contributed an additional 12 percentage points to participation).³ “This approach mirrors the strategies by Color [Health] and the American Cancer Society, which also focus on enhancing patient support and ensuring timely follow-up care,” she says.

She also points to a systematic review and meta-analysis showing that repeated FIT can improve the detection of colorectal cancer, which she says underscores its effectiveness in increasing sensitivity and minimizing missed cases.⁴