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One-time sigmoidoscopy reduced colorectal cancer mortality but not incidence
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Patients who attended one-time sigmoidoscopy screening examinations had a 27% reduction in colon cancer mortality and a 37% reduction in rectosigmoidal cancer mortality compared with patients who were not screened, according to the interim results of the Norwegian Colorectal Cancer Prevention (NORCCAP) trial. Despite this, screening after seven years of follow-up did not reduce the incidence of colorectal cancer in screened patients.
“Since site-specific cancer mortality is generally considered the most appropriate endpoint for evaluating screening interventions, we should be encouraged by NORCCAP’s interim findings,” Thomas F. Imperiale, MD, professor of medicine at Indiana University Medical Center, wrote in an accompanying editorial. “Evidence to date strongly suggests that one-time screening sigmoidoscopy can reduce incidence and mortality from distal colorectal cancer and may be a legitimate strategy.”
In the population-based, randomized, controlled trial, 55,736 people aged 55 to 64 were randomly assigned to screening with flexible sigmoidoscopy with or without fecal occult blood test or to a control group. The primary endpoint was cumulative incidence and mortality at five, 10 and 15 years. These results are an interim report of incidence at seven years and mortality at six years.
Of the 13,653 patients in the screening group, 8,846 people attended a screening exam.
There was no difference in incidence of colorectal cancer found between the screening and control groups (134.5 vs. 131.9 cases per 100,000 person years). In an intention-to-screen analysis there was a 27% reduction in mortality for colorectal cancer (95% CI, 0.47-1.13) and a 37% reduction in mortality from rectosigmoidal cancer (95% CI, 0.34-1.18) among patients who were assigned screening.
Mortality was reduced further when the analysis was limited to patients who actually attended a screening. Those who attended had a 59% reduced mortality from colorectal cancer (95% CI, 0.21-0.82) and a 76% reduced mortality for rectosigmoidal cancer (95% CI, 0.08-0.76).