Tumor markers are substances in the body that can indicate cancer. In Germany, they play an important role in laboratory medicine, particularly in the diagnosis, monitoring and aftercare of cancer.

What are tumor markers?

Tumor markers are usually proteins, hormones or other molecules that are produced by tumor cells or released in the body as a reaction to cancer. They can be detected in blood, urine or tissue. Well-known examples are PSA (prostate-specific antigen) in prostate cancer, CEA (carcinoembryonic antigen) in colorectal cancer or AFP (alpha-fetoprotein) in liver cancer. Each tumor marker is associated with certain types of cancer, but not every marker is elevated in every patient.

How are tumor markers measured?

In laboratory medicine, a blood sample is usually taken, sometimes also urine or tissue. Special equipment is used to check whether and how much of a tumor marker is present. The values are then compared with normal values. An elevated value can indicate cancer, but can also have other causes, such as inflammation. This is why tumor markers are rarely used on their own, but are combined with imaging (e.g. MRI) or biopsies.

Why are tumor markers important?

Tumor markers can help to detect cancer at an early stage, even before symptoms appear – for example in PSA tests for prostate cancer screening. They are also useful for checking whether a therapy such as chemotherapy is working: if the marker drops, this is a good sign. After treatment, they show whether the cancer has returned, which is crucial for follow-up care. In Germany, where laboratory medicine is very precise, they are a valuable tool for doctors and patients.

Limits and challenges

Tumor markers are not infallible. A high value does not always mean cancer – benign diseases can also increase them. Conversely, a normal value cannot rule out cancer. In Germany, the results are therefore interpreted carefully, often in combination with other tests, in order to avoid misdiagnosis.

Conclusion

Tumor markers are an important component of laboratory medicine. They support the early detection, therapy monitoring and aftercare of cancer and help to make treatment more targeted. Even if they cannot do everything, they provide valuable information – a small test that provides great clarity.

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Gender note. The personal designations used in this text always refer equally to female, male and diverse persons. Double/triple references and gendered designations are avoided for the sake of better readability ected.