Early detection of colon cancer by flexible sigmoidoscopy in men

This fact box will help you to weigh the benefits and harms of early detection of colorectal cancer with flexible sigmoidoscopy in men. The information and numbers are based on the best scientific evidence currently available.

This fact box was developed by the Harding Center for Risk Literacy.

What is colon cancer?

In 2014, around 61,000 people in Germany were diagnosed with colon cancer, of whom around 33,000 were male. Colon cancer is more common in people over the age of 55 [4].

Colon cancer develops in the intestinal mucosa (mucous membrane) in the colon, usually through precancerous lesions called polyps. Polyps are benign mucosal tumors that protrude into the colon and can develop into colon cancer.

What is colon cancer screening with flexible sigmoidoscopy?

Early detection screening targets people who do not have any symptoms of a particular disease (in this case, colon cancer). The aim is to detect and treat the cancer at an early stage in order to increase chances of survival or recovery.

Flexible sigmoidoscopy involves using an endoscope (flexible mirror imaging or sigmoidoscope) to examine the last 24 inches or so of the colon. With an endoscope it is possible to view the inside wall of the colon and examine it for abnormalities. In addition, if any potential precursors of colon cancer, known as polyps, are found, they can be removed directly during the procedure.

Who might consider colon cancer screening with flexible sigmoidoscopy?

In Germany, sigmoidoscopy as a colon cancer screening test is not covered by statutory health insurance.

What are alternative treatment options?

Other colon cancer screening tests include the fecal occult blood test (FOBT), which tests for blood in the stool, and colonoscopy, which examines a larger portion of the colon [5]. These are covered by statutory health insurance in Germany for adults aged 50 years and older and 55 years and older, respectively.

Fact box early detection of colon cancer by flexible sigmoidoscopy in men
Fact box early detection of colon cancer by flexible sigmoidoscopy in men © Harding Center for Risk Literacy
What does the fact box show?

The fact box shows the benefits and harms of colon cancer screening by flexible sigmoidoscopy compared to no colon cancer screening in men.  

The table may be read as follows:

5 out of every 1,000 men aged 50 and over who did not participate in the screening and 3 out of every 1,000 men who participated in screening died from colon cancer over a time period of approximately 10 years.

This means that, compared to men who did not participate in screening,  2 fewer men out of 1,000 died from colon cancer with screening. 

The numbers in this fact box are rounded. The numbers concerning colon cancer mortality and diagnoses are calculated from three studies that included a total of around 300,000 participants [1]. The numbers regarding complications are calculated from four studies that included around 450,000 participants [2]. The numbers regarding pain are taken from one study with 170,000 participants [3]. 

What other aspects should be considered?

The screening test showed no effect on the number of deaths when all possible causes of death were observed. This means that although 2 fewer men died from colon cancer over the course of 10 years, there was no overall reduction in deaths from any cause [2].

Do the results provide proof (evidence) for the benefits and harms of the screening through small colonoscopy?

Overall, the evidence is of moderate quality. Further research is likely to have an important impact on some findings [1].

The authors did not carry out a quality assessment of the results concerning the risks. That means that it is not known how reliable the data are. 

Version history of the fact box
  • June 2019 (update of evidence, implementation of gender-specific endpoints)
  • June 2016 (creation)

Information within the fact box was obtained from the following sources:

[1] Holme O, Schoen RE, Senore C, et al. Effectiveness of flexible sigmoidoscopy screening in men and women and different age groups: pooled analysis of randomised trials. BMJ (Clinical research ed) 2017;356:i6673. doi: 10.1136/bmj.i6673.

[2] Fitzpatrick-Lewis D, Ali MU, Warren R, et al. Screening for Colorectal Cancer: A Systematic Review and Meta-Analysis. Clin Colorectal Cancer 2016;15(4):298-313. doi: 10.1016/j.clcc.2016.03.003.

[3] Atkin WS, Cook CF, Cuzick J, et al. Single flexible sigmoidoscopy screening to prevent colorectal cancer: baseline findings of a UK multicentre randomised trial. Lancet 2002;359(9314):1291-300. doi: 10.1016/s0140-6736(02)08268-5.

[4] Robert Koch Institut. Zentrum für Krebsregisterdaten. Darmkrebs 2014. [https://www.krebsdaten.de/Krebs/DE/Content/Krebsarten/Darmkrebs/darmkrebs_node.html] 22.05.2019.

[5] Gemeinsamer Bundesausschuss. Früherkennungsuntersuchungen im Überblick 2016 [www.g-ba.de/institution/themenschwerpunkte/ frueherkennung/ueberblick/] 01.11.2016.

Documentation on how the numbers in the fact box were determined is available on request.