Bowel cancer screening: What the halt to the vaccine trial means – and what really offers protection now

In August 2026, a Phase 2 trial by BioNTech involving the drug candidate Autogene Cevumeran was terminated. This was a personalised mRNA immunotherapy. It was tested on people whose bowel cancer had already been surgically removed and who were at increased risk of recurrence. The aim was to help the immune system recognise and attack any remaining cancer cells.

It is important to distinguish this from prevention: the drug under investigation was not a vaccine for healthy people designed to prevent bowel cancer. The trial focused on treatment following a previous cancer diagnosis and surgery.

During the evaluation, an independent monitoring committee identified a numerical difference in overall survival between the groups under investigation and therefore recommended that the study be terminated. According to BioNTech, no new safety signals were identified. Research into new immunotherapies for cancer is continuing as a matter of course.

A colonoscopy is a way of examining the large bowel particularly thoroughly. During the procedure, the doctor can directly examine the intestinal lining and identify any suspicious changes. The advantage is that not only can tumours that have already developed be detected, but also bowel polyps, which can change over the years and develop into cancer. If they are removed during the examination, this can prevent the development of a tumour at a later stage.

How often a colonoscopy is advisable depends, amongst other things, on age, the results of the examination and individual risk.

Another option is a test for blood in the stool. This involves taking a small stool sample at home, which is then analysed. The blood is often not visible to the naked eye. The test is straightforward and helps to detect abnormalities at an early stage. However, it does not directly indicate where the blood is coming from. Furthermore, polyps or tumours do not bleed constantly, so a single test may show no abnormalities even though a change is present. A positive result therefore warrants a colonoscopy.

The main differences:

Colonoscopy: direct examination of the bowel – polyps can usually be removed immediately.

Stool test: a simple test carried out at home – it checks for hidden blood.

Abnormal stool test: a colonoscopy is then required to investigate further.

Bowel cancer often develops over a long period of time. It can start with an adenoma – a benign polyp on the lining of the bowel. However, not every adenoma develops into cancer. Certain changes can, however, progress over several years. A polyp that is initially benign can eventually develop into a malignant tumour. This gradual process is known as the adenoma-carcinoma sequence.

The risk of bowel cancer increases primarily with age. Genetic factors and family history may also play a role. Anyone with close relatives who have had bowel cancer or certain types of bowel polyps should discuss this with their doctor. Personal lifestyle choices can also influence the risk of developing the disease.

These include, amongst others:

• smoking
• regular heavy alcohol consumption
• severe obesity
• insufficient physical activity
• a diet low in fibre
• frequent consumption of processed meat
• certain chronic inflammatory bowel diseases

A single risk factor does not automatically mean that bowel cancer will develop. However, several factors can reinforce each other.

Before the examination, the bowel must be completely cleansed. To do this, a special laxative is taken according to a specific schedule. For many people, the preparation is the most unpleasant part of the examination.

During a colonoscopy, a thin, flexible tube fitted with a small camera is carefully inserted into the bowel via the anus to examine the lining for any changes. If polyps are found, they can be removed straight away. Larger or suspicious changes are sent to the laboratory for further examination. The examination takes around 15 to 45 minutes, and a sedative or anaesthetic can be administered on request.

New vaccines and immunotherapies are important areas of cancer research. However, established procedures are already available today for colorectal cancer screening. A colonoscopy, in particular, offers the opportunity not only to detect cancer at an early stage, but also to remove certain precancerous lesions straight away.