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One-time Sigmoidoscopy in Screening for CRC

Colorectal cancer (CRC) is the 3rd most prevalent cancer in the United States (Siegel, Ward, Brawley & Jemal, 2011). The good news is that there are acceptable and proven methods for CRC screening (Smith et al, 2011). The gold standard for CRC screening is a colonoscopy (Smith et al, 2011); however, researchers are investigating alternate and less frequent screening protocols in order to increase screening adherence and decrease screening-related morbidity. An Italian study group has published data on the evaluation of a single flexible sigmoidoscopy at around the age of 60 years as an effective strategy for CRC screening (Segnan et al, 2011).

Study Details


A randomized controlled trial to evaluate the effect of flexible sigmoidoscopy screening on CRC incidence and mortality. A questionnaire to assess the eligibility and interest in screening was mailed to 236,568 men and women, aged 55–64 years, who were randomly selected from six trial centers in Italy. Of the 56,532 respondents (24% response rate), interested and eligible subjects were randomly assigned to the intervention group (invitation for flexible sigmoidoscopy; n = 17,148) or the control group (no further contact; n = 17,144), between 1995 and 1999. Flexible sigmoidoscopy was performed on 9,911 subjects. Intention-to-treat and per-protocol analyses were performed to compare the CRC incidence and mortality rates in the intervention and control groups. Per-protocol analysis was adjusted for noncompliance.


A total of 34,272 subjects (17,136 in each group) were included in the follow-up analysis. The median follow-up period was 10.5 years for incidence and 11.4 years for mortality; 251 subjects were diagnosed with CRC in the intervention group and 306 in the control group. Overall incidence rates in the intervention and control groups were 144.11 and 176.43, respectively, per 100,000 person-years. CRC-related death was noted in 65 subjects in the intervention group and 83 subjects in the control group. Mortality rates in the intervention and control groups were 34.66 and 44.45, respectively, per 100,000 person-years. In the intention-to-treat analysis, the rate of CRC incidence was statistically significantly reduced in the intervention group by 18% (rate ratio [RR] = 0.82, 95% confidence interval [CI] = 0.69 to 0.96), and the mortality rate was non-statistically significantly reduced by 22% (RR = 0.78; 95% CI = 0.56 to 1.08) compared with the control group. In the per-protocol analysis, both CRC incidence and mortality rates were statistically significantly reduced among the screened subjects; CRC incidence was reduced by 31% (RR = 0.69; 95% CI = 0.56 to 0.86) and mortality was reduced by 38% (RR = 0.62; 95% CI = 0.40 to 0.96) compared with the control group.

The SCORE study group concluded that a single flexible sigmoidoscopy screening between ages 55 and 64 years was associated with a substantial re¬duction of CRC incidence (31%) and mortality (38%). The authors also note that because of a self-selection bias in trial recruitment, a longer follow-up of at least 14 years may be needed to see a 25% statistically significant reduction in mortality in the intervention group compared with the control group (Segnan et al, 2011).

ManageCRC.com Commentary

Despite numerous studies and consumer articles supporting colonoscopy as the preferred method of CRC screening, many people are reluctant to undergo colonoscopy. The reasons include fear of the procedure, perceived discomfort, potential risk, and anticipated costs. Continued research into alternate methods of screening is helping to advance the science and perhaps lead to a less invasive, safer CRC screening protocol that may be more acceptable to more people. The authors of this study clearly note that, while the findings were positive, a single sigmoidoscopy as a screening method needs further research to verify outcomes over time. Flexible sigmoidoscopy is limited somewhat by its inability to visualize the entire colon; comparative studies of sigmoidoscopy and colonoscopy are needed before sigmoidoscopy can be considered equal to colonoscopy. As the worldwide population ages, the importance of screening for common cancers that are curable when caught early becomes even more important in terms of allocation of healthcare resources, quality of life and overall survival.


Segnan, N., Armaroli, P., Bonelli, L., Risio, M., Sciallero, S., Zappa, M.,…SCORE Working Group. (2011). Once-Only Sigmoidoscopy in Colorectal Cancer Screening: Follow-up Findings of the Italian Randomized Controlled Trial—SCORE. Journal of the National Cancer Institute, 103, 1310–1322. doi:10.1093/jnci/djr284 Link to abstract http://jnci.oxfordjournals.org/content/103/17/1310.abstract 

Siegel, R., Ward, E., Brawley, O., Jemal, A. (2011) Cancer statistics, 2011. CA: A Cancer Journal for Clinicians, 61, 212-236. doi:10.3322/caac.20121 Link to free full-text http://caonline.amcancersoc.org/cgi/content/full/61/4/212

Smith, R.A., Cokkinides, V., Brooks, D., Saslow, D., Shah, M., & Brawley, O.W. (2011). Cancer Screening in the United States, 2011: A Review of Current American Cancer Society Guidelines and Issues in Cancer Screening.CA: A Cancer Journal for Clinicians, 61, 8–30. doi:10.3322/caac.20096 Link to free full-text http://onlinelibrary.wiley.com/doi/10.3322/caac.20096/pdf

Article Created On : 9/14/2011 9:29:47 AM             Article Updated On : 9/14/2011 9:29:47 AM