{'fraction_non_alphanumeric': 0.02368896925858951, 'fraction_numerical': 0.010488245931283906, 'mean_word_length': 5.753357753357753, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Flexible sigmoidoscopy for colorectal cancer screening: more evidence, persistent ironies.

In this issue of JAMA, Holme and colleagues1 report results of a large randomized trial of colorectal cancer screening in Norway in which one-time flexible sigmoidoscopy was compared with no screening. In intention-to-screen analysis— which included all people invited for screening, regardless of their follow-through—relative reductions in colorectal cancer incidence and cancer-specific mortality were 20% and 27% in the sigmoidoscopy group, respectively, compared with the no-screening control group, during an average follow-up of about 11 years. In absolute terms, colorectal cancer death was averted in 1 person per 1000; cancer-specific mortality was roughly 4 per 1000 in the control group and 3 per 1000 in the sigmoidoscopy group. Colorectal cancer mortality curves did not diverge until the ninth year, suggesting that the benefit of screening might increase with longer follow-up. Additionally, because only two-thirds of people invited for screening actually participated, the population benefit would likely be higher with greater adherence. Half the sigmoidoscopy group also received one-time immunological fecal occult blood testing (FOBT), but this addition did not improve outcomes beyond sigmoidoscopy alone. This is the fourth large randomized trial of sigmoidoscopy screening conducted in recent years. The trials—from the United Kingdom,2 Italy,3 United States,4 and now Norway—differ in various ways that could have affected outcomes, including participant recruitment, degree of “contamination” (ie, screening outside the trial) in control groups, and abnormalities on sigmoidoscopy that mandated subsequent colonoscopy. Nevertheless, the relative and absolute reductions in colorectal cancer–specific mortality are similar across the trials. In the Norwegian study, selection of participants was population based and control group contamination was minimal. About 20% of those who underwent sigmoidoscopy were referred for full colonoscopy, triggered by a finding of any adenomatous polyp (no matter how small) at sigmoidoscopy. Among those who underwent colonoscopy after abnormal sigmoidoscopy findings, colonic perforation occurred in 6 of 2520, a somewhat higher rate than previously reported5; no perforations were reported during nearly 13 000 sigmoidoscopic procedures. The publication of yet another study of flexible sigmoidoscopy highlights an irony for US clinicians: By far, colonoscopy has become the most commonly recommended and performed endoscopic colorectal cancer screening tool in the United States, whereas screening by sigmoidoscopy has all but vanished.6 Fecal occult blood testing persists unevenly—for example, in managed care organizations that actively promote it to their enrollees and in uninsured or underinsured populations without affordable access to colonoscopy. The transition to screening colonoscopy among average-risk persons in the United States accelerated in 2001, when Medicare began paying for it and many private insurers followed. Gastroenterologists began to recommend colonoscopy as the test of choice and had economic incentives to do so. As one gastroenterologist observed recently, “Colonoscopy has been really good to our specialty. It is the goose that has laid the golden egg.”7 In many other developed nations, FOBT remains the dominant mode of screening.8 Another ironic aspect of the decline of flexible sigmoidoscopy in the United States is that randomized trial–level evidence of reduced cancer-specific mortality exists for flexible sigmoidoscopy and FOBT but not for colonoscopy or the other available structural screening test, computed tomography colonograpy. Those who suggest that population-wide cancer screening should be supported by randomized trials thus maintain that sigmoidoscopy and FOBT are still appropriate initial screening options. In contrast, proponents of colonoscopy maintain (with support from some observational studies) that examining the entire colon must be preferable to examining half of it. That argument, although compelling, overstates the case for the benefit of initial colonoscopy somewhat because patients with adenomas at sigmoidoscopy are then referred for full colonoscopy. There is room for both views. Decision analysis suggests that with good adherence, the gain in life-years with a combination of flexible sigmoidoscopy (performed every 5 years) plus sensitive FOBT (performed periodically) is similar to that of colonoscopy (performed every 10 years).9 In the United States, multiple screening options and multiple competing recommendations create quandaries for primary care physicians who try to follow practice guidelines. Primary care–oriented organizations (for example, the US Preventive Services Task Force10 and the American College of Physicians11) tend not to favor any one colorectal screening mode for average-risk adults. Instead, they advise clinicians to elicit patients’ preferences and engage in shared decision making. As the American College of Physicians states, “shared decision making is important when selecting a screening test because the currently available colorectal cancer screening tests are believed to be similarly efficacious. Clinicians should discuss the benefits, harms, effectiveness, safety, and costs of the [available] options.”11 Although I am sympathetic to the ideal of highly informed, shared decision making—espoused not only for Related article page 606 Opinion