Screening for colorectal cancer in people with a family history: benefit for under 55-year-olds is unclear

It is unclear whether people younger than 55 years of age with a family member already affected by colorectal cancer benefit from a screening test, as suitable studies are lacking so far. This is the conclusion of the final report of the German Institute for Quality and Efficiency in Health Care (IQWiG) published on 26 July 2013.

Occult blood testing and colonoscopy depending on age

Colorectal cancer is the second most common form of cancer and the second most common cancer-related cause of death in Germany, both in men and in women. About 25% of these cases show a familial clustering; however, a specific genetic cause can only be determined in about 5% of cases (hereditary form).

Between the age of 50 and 54 years all health insurance fund members are entitled to faecal occult blood testing and, in the case of a suspicious result, to a colonoscopy. From the age of 55 years onwards, members of the health insurance funds can choose between faecal occult blood testing every two years or a colonoscopy.

Fixed age limits under scrutiny

The cancer screening and cancer registry law, effective since April 2013, has abolished these fixed age limits. Instead, the Federal Joint Committee ( Gemeinsamer Bundesausschuss, G-BA) is to specify medical criteria. For instance, groups of patients regarded to be at risk can be offered a screening test earlier or more often. The National Cancer Plan of the German Federal Ministry of Health also recommends examining the implementation of so-called risk-adapted screening.

The G-BA has commissioned IQWiG to examine whether under 55-year-olds who have relatives affected by colorectal cancer have a higher risk of cancer themselves, and to examine how reliably they can be identified.

In addition, the G-BA hopes to gain knowledge concerning what benefit people with a family history have if they take part in a “modified” screening programme.

This does not only mean that screening tests are initiated at a younger age. For instance, the tests can also take place at different time intervals, or the first measure could be a colonoscopy, not faecal occult blood testing. Hereditary forms of colorectal cancer were explicitly not specified as a subject of the report.

Risk is clearly increased if relatives have colorectal cancer

As IQWiG determined, under 55-year-olds with at least one first-degree affected relative have a 1.7 to 4.1 times higher risk of developing colorectal cancer than people of the same age without an affected relative.

IQWiG also examined how reliably the family history of diseases can be recorded, for example by means of questionnaires or interviews (diagnostic accuracy). Two studies could be included in the assessment. However, they allow no conclusions on the group of under 55-year-olds or on questionnaires in general or German-language instruments in particular.

Informative studies in under 55-year-olds are lacking

The question also remained unanswered as to what benefit a screening strategy has in which initially people with a family history are to be identified who are subsequently offered a screening test. This is because currently no informative studies on this topic are available. Likewise no study results are currently available on the benefit of screening procedures in people in whom a higher risk of colorectal cancer has already been determined.

Screening tests also have risks

As the final report shows, overall the evidence base is poor. It must carefully be balanced whether it is nevertheless justified to introduce a risk-adapted screening strategy. This is because such tests not only have the potential to achieve a benefit, but may also cause harm. This has also been described in detail by the authors of the National Cancer Plan. For instance, harm can be caused by people being wrongly allocated to a risk group, causing unnecessary psychological stress.

Process of report production

IQWiG published the preliminary results in the form of the preliminary report in September 2012 and interested parties were invited to submit comments. At the end of the commenting procedure the preliminary report was revised and sent as a final report to the contracting agency, the Federal Joint Committee (G-BA), in May 2013. The submitted written comment was published in a separate document at the same time as the final report. The report was produced in collaboration with external experts.