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Sigmoidoscopy screening reduces colorectal cancer incidence, mortality in men
A one-time sigmoidoscopy screening reduced colorectal cancer incidence and mortality in men, though little or no effect was observed in women, according to a Norwegian study published today in Annals of Internal Medicine.
“Sigmoidoscopy is highly effective in men, and the effect is long lasting. For women, other options should be discussed,” Øyvind Holme, MD, PhD, associate professor at the University of Oslo, Norway, told Healio Internal Medicine.
Holme and colleagues used the National Registry to identify 98,678 women and men aged 50 to 64 years in Oslo and Telemark County, Norway, who were eligible for screening between 1999 and 2001. Participants were randomly assigned to one-time screening with flexible sigmoidoscopy with or without additional fecal blood testing (n = 20,552), or to no screening (n = 78,126). Those with a history of colorectal cancer were excluded.
Adherence rates were 64.7% in women and 61.4% in men, with a median follow up of 14.8 years. Holme and colleagues observed a 1.86% absolute risk for colorectal cancer in women in the screening group compared with 2.05% in the control group (risk difference = –0.19 percentage point [95% CI, –0.49 to 0.11]; HR = 0.92 [95% CI, 0.79-1.07]). The corresponding risk for colorectal cancer in men in the screening group was 1.72% compared with 2.5% in the control group (risk difference = –0.78 percentage point [95% CI, –1.08 to –0.48]; HR = 0.66 [95% CI, 0.57-0.78]; P for heterogeneity = .004).
Researchers determined that the absolute risks for death from colorectal cancer in women was 0.60% in the screening group and 0.59% in the control group (risk difference = 0.01 percentage point [95% CI, –0.16 to 0.18]; HR = 1.01 [95% CI, 0.77-1.33]). The risks for death in men who were screened vs. those who were not were 0.49% and 0.81%, respectively (risk difference = –0.33 percentage point [95% CI, –0.49 to –0.16]; HR = 0.63 [95% CI, 0.47-0.83]; P for heterogeneity = .014).
The researchers suggested that the disparities among men and women in the study may be due to sex differences in the colorectal cancer risk profile among those who adhered to screening and those who did not. Another explanation, they added, is a higher prevalence of adenomas among men at the time of sigmoidoscopy screening, and they were therefore referred for colonoscopy more often than women.
In a related editorial, Kirsten Bibbins-Domingo, PhD, MD, MAS, the Lee Goldman, MD, Endowed Chair in Medicine at the University of California, San Francisco, and John M. Inadomi, MD, the Cyrus E. Rubin Endowed Chair in Medicine at the University of Washington School of Medicine, said an “earlier peak incidence of [colorectal cancer] in men than women” could be a reason for the disparities between the sexes.
“The potential contribution of this epidemiologic difference is supported by the greater age-specific incidence in men than women in the control group,” they wrote. “Thus, with [one-time] screening, the age at screening may be too early to capture most women who will develop cancer.”
Holme emphasized that sigmoidoscopy should be regarded as a valid option for men.
“It does not require any bowel cleansing before you attend the screening premises, and most people do not experience pain during the examination,” he said. “It only takes on average 5 minutes, and the effect is, according to our results, long lasting. For women, however, other screening tools should be considered.” – by Marley Ghizzone
Disclosures: Holme reports receiving fees for lectures from Norgine. Please see the study for all other authors’ relevant financial disclosures. Bibbins-Domingo and Inadomi report no relevant financial disclosures.