Medically Reviewed by: Nicole Anne Vergara, RD
Colonoscopies have been promoted by gastroenterologists for many years. According to physician and researcher Michael Bretthauer from Norway, if everyone underwent the test merely once every ten years, colon cancer would essentially become “extinct.” However, brand-new findings from a clinical experiment he directed cast doubt on colonoscopy’s dominance.
The colonoscopy test’s effectiveness was shown to be substantially below previous projections in the trial’s primary analysis, which also revealed that it did not significantly reduce colon cancer mortality. Instead, it only reduced colon cancer risk by around a fifth. Bretthauer and other gastroenterologists reacted to the trial’s findings with a mix of amazement, disappointment, and even slight disbelief.
Gastroenterologist Samir Gupta, who wasn’t involved in the experiment and works at the VA and the University of California, San Diego, made a point of saying, “This is a landmark study. It’s the first randomized trial showing outcomes of exposing people to colonoscopy screening versus no colonoscopy. And I think we were all expecting colonoscopy to do better…Maybe colonoscopy isn’t as good as we always thought it is.”
He emphasized that the study did not disprove the value of colonoscopies as a screening method. Even while colonoscopies are still an excellent test, Gupta suggested that it could be time to reconsider their status as the most effective way to detect colon cancer.“This study provides clear data,” he said, “that it’s not as simple as saying, ‘Colonoscopy is the most sensitive test, and therefore it is the best.’ It still prevented cancers.”
Colonoscopies involve placing a camera up the rectum to look for adenomas, or pre-cancerous polyps. When an endoscopist finds a suspicious polyp, the polyp is swiftly removed, halting the spread of the cancer. Previous studies consistently demonstrated that colonoscopy might significantly reduce the incidence and death of colon cancer, by about 70%.
However, neither of those studies were big randomized trials, which are the gold standard of clinical research experiments. In order to determine whether colonoscopy was really as effective as they all believed, Bretthauer of the University of Oslo and Oslo University Hospital and a number of colleagues began one ten years ago. They enrolled more than 80,000 people in Poland, Norway, and Sweden between the ages of 55 and 64. A colonoscopy invitation was sent to around 28,000 of the participants at random, while the remaining participants received their regular care, which did not involve routine colonoscopy screening.
Following that, the researchers recorded colonoscopies, colon cancer diagnoses, colon cancer fatalities, and all other deaths. The patients who were invited to a colonoscopy had an 18% lower risk of developing colon cancer after 10 years, but they were no less likely to pass away from the disease than those who were not invited. Only 42% of those who were offered to have a colonoscopy actually did so. On Sunday, the group published its findings in the New England Journal of Medicine.
The findings don’t line up with certain earlier studies in other colon cancer screenings. “We know from other screening tests that we can reduce cancer mortality by more than this,” This was stated by Jason Dominitz, who did not participate in the research and is the executive director of the VA’s national gastroenterology and hepatology program. Dominitz noted that randomized studies have demonstrated a reduction in colon cancer mortality with sigmoidoscopy, which only looks at a smaller part of the colon. He also pointed out. “Colonoscopy is sigmoidoscopy and more, so you’d think it can’t be less effective than sigmoidoscopy,”
Dominitz said there are numerous nuanced ways to analyze the data. For starters, only a small portion of individuals who were invited to a colonoscopy really went through with it. This might have lessened the colonoscopy advantages that were noted in the study. The study has only had 10 years of follow-up, and cancer treatment has advanced over the past few decades, making it more challenging to detect a mortality advantage from the screen. “They’re doing a 15-year follow, and I would expect to see a significant reduction in cancer mortality in the long term,” Dominitz said. “Time will tell.”
In spite of the fact that cancer treatment has advanced to the point where a 15-year follow-up shows no mortality decrease, UCSD’s Gupta said that preventing cancer can still be quite advantageous. The study nonetheless shown that colonoscopies decreased the risk of developing cancer, which also translated into fewer operations, chemotherapies, immunotherapies, and other unpleasant experiences.
Another silver lining can be found in a secondary analysis, according to Gupta. The researchers found a 30% reduction in colon cancer risk and a 50% reduction in colon cancer death when they only looked at the 42% of people in the invited group who actually showed up for a colonoscopy. According to a number of observational study findings, having a colonoscopy may lower a person’s chance of both acquiring and dying from colon cancer, according to Gupta.
However, the primary or intention-to-treat analysis is more reliable than the secondary analysis. The analysis you completely trust is the intention-to-treat analysis, according to Bretthauer of Oslo. This has caused him to wonder if he and everyone else in the area of colon cancer were mistaken about the true value of colonoscopy.
It’s not the cure we had anticipated, he declared. “I believe the colonoscopy may have been oversold. If everyone underwent a colonoscopy, there would be a 70, 80, or even 90% reduction in colon cancer, according to the gastroenterology societies, of which I am a member. These data don’t support that.”
Instead, he suggested that the true benefit of colonoscopy screening might be found somewhere between the primary and secondary analyses in his study. Getting a colonoscopy could lower your risk of developing colorectal cancer between 20 to 30%, according to Bretthauer. That puts it more in line with the other primary colorectal cancer tests, which examine feces for indications of cancer and may be performed at home. These tests look for aberrant DNA or blood.
That brings up a crucial issue for decision-makers, Bretthauer continued. Colonoscopy is more expensive, time-consuming, and unpleasant for people before the procedure. He claimed that several European nations resisted allocating public health funds to a sizable, pricey program when fecal testing was less complicated, less expensive, and had higher uptake in some trials.
What Is The Best Way To Screen For Colorectal Cancer?
According to Dominitz, this randomized controlled experiment was designed to evaluate the utility of counseling in addition to the usefulness of colonoscopies. Overall, the study discovered that simply encouraging people to undergo a colonoscopy had little to no positive effects in these countries, in part because so many people chose not to.
Dominitz believes that the study’s setting can help to partially account for the poor participation. Colonoscopies are less common than they are in the United States in the study’s participating nations. He claimed that formal recommendations for colorectal cancer screening in Norway didn’t arrive until only last year.
Approximately 1 in 5 persons in the US between the ages of 50 and 75 have never had a colorectal cancer screening, according to data from the US Centers for Disease Control and Prevention.
There are other procedures and regimens that can be used to detect colorectal cancer if you are uncomfortable having a colonoscopy, according to the US Preventive Services Task Force. It advises screening every one to three years with tests that look for blood and/or cancer cells in stool, every five years with a colonoscopy and a flexible sigmoidoscopy, every ten years with a flexible sigmoidoscopy and a stool test to look for blood every year, or every ten years with a colonoscopy alone.
Due to the fact that colorectal cancer is becoming more prevalent in younger persons, the task force lowered the recommended age to begin routine screening for the disease from 50 to 45 in 2021.
According to Dominitz, tests for colorectal cancer can only be successful if patients are ready to participate in them.
He cites preliminary findings from a sizable Swedish randomized trial that compares colonoscopy, FIT testing, and no screening at all as evidence.
Pan, Jun, et al. “Colonoscopy Reduces Colorectal Cancer Incidence and Mortality in Patients With Non-Malignant Findings: A Meta-Analysis – PMC.” PubMed Central (PMC), 12 Jan. 2016, www.ncbi.nlm.nih.gov/pmc/articles/PMC4820666.
“Colonoscopy Reduces Colorectal Cancer Incidence and Mortality in Patients With Non-Malignant Findings: A Meta-Analysis.” The New England Journal of Medicine, www.nejm.org/doi/full/10.1056/NEJMoa2208375. Accessed 12 Oct. 2022.
“Understanding the Results of a Randomized Trial of Screening Colonoscopy.” The New England Journal of Medicine, www.nejm.org/doi/full/10.1056/NEJMe2211595. Accessed 12 Oct. 2022.