According to an investigation published online today in the Journal of National Cancer Institute, a single flexible sigmoidoscopy screening between the ages of 55-64 years is linked with a reduced level of colorectal cancer (CRC) incidence and mortality.

Several randomized controlled investigations have revealed that fecal occult blood testing (FOBT) in CRC screening of patients diagnosed with CRC can reduce the mortality rate. Observational studies and an earlier randomized trial from the U.K., known as SCORE, have shown a decrease in incidence and mortality for cancer in the rectum and sigmoid colon (distal CRC) among patients who had undergone endoscopy. Which suggests long-term protection against the development of distal CRC can be provided by the removal of adenomas at screening.

To find out if the flexible sigmoidoscopy is a useful prevention method in CRC screening, the investigators, led by Nereo Segnan, M.D., of the Epidemiology Unit at S. Giovanni University Hospital in Turin, Italy, mailed a survey investigating subjects in FS screening to a random population sample of men and women who were aged between 55 and 64 years old. Responders who were interested and eligible were randomly designated to either the control group (N= 17148 - no further contact) or intervention group (N=17144 - invitation for flexible sigmoidoscopy).

Flexible sigmoidoscopy was carried out on 9,991 subjects, of which, 9,387 (94.71%) were discharged, while 55 (0.55%) were referred for surgery, 395 for follow-up surveillance colonoscopy, and the 74 patients who remained did not comply with the recommended total colonoscopy evaluation. For CRC incidence the median follow-up period was 10.5 years and 11.4 years for all-cause and CRC specific mortality. 557 people (including those detected at initial screening) were diagnosed with CRC and 148 people died of the disease during this period.

The investigators discovered that in the intent-to-treat analysis, CRC incidence and mortality were reduced by 18% and 22% respectively. For those who were screened (per protocol analysis) CRC incidence was reduced by 31%, and 46% for advanced CRC cases. In addition, CRC mortality was statistically significantly reduced by 38% in screened subjects in comparison to the control group.

The researchers write that the reported discoveries, which are consistent with the observed reduction of CRC incidence and mortality among people screened in the recently published UK Flexible Sigmoidoscopy Screening Trial, support the theory that Flexible sigmoidoscopy screened offered only one time, represents a safe and effective method for CRC screening and ensures a long lasting reduction of CRC risk. A longer follow-up is necessary to fully evaluate the impact on mortality and to estimate the duration of the protective effect, according to the researchers.

In an associated editorial, Timothy R. Church, Ph.D., of the University of Minnesota, writes about what the best method to CRC screenings may be. Underlying the three primary CRC tests (flexible sigmoidoscopy, FOBT, and colonoscopy), Church states that a cost-effective examination is an important factor in determining the best available method, explaining that these costs are driven by not only the up-front infrastructure costs of laboratories, equipment, endoscopy facilities, training, and manufacturing, but also by the rates of false-positive results.

Due to none of the standard three approaches to CRC screening being more effective than the other, Church also argues that until more substantial evidence is gathered, endorsing all three techniques is the best approach to attach CRC. Should results from tests conflict, Church says, "Any concerns about the potential confusion that arises from multiple approaches may be balanced by the advantages of tailoring screening to the preferences of the patient."

Written by Grace Rattue