[Molecular testing and liquid biopsies in colorectal cancer].

BACKGROUND

The introduction of new DNA sequencing technologies has led to the discovery of many prognostically and predictively relevant biomarkers in tumor tissue and blood from patients with colorectal cancer.

OBJECTIVES

Presentation of meaningful tissue-based molecular pathological diagnostics and discussion of the clinical application of circulating tumor DNA (ctDNA) from liquid biopsies in colorectal cancer.

MATERIALS AND METHODS

Evaluation of existing literature and congress publications, discussion of post hoc analyses of clinical studies and expert recommendations.

RESULTS

In Union for International Cancer Control (UICC) stages II/III, the tissue-based evaluation of microsatellite instability (MSI-H) contributes to individual therapy optimization through advice on adjuvant chemotherapy (colon cancer, UICC II) or, if necessary, individual neo-adjuvant therapy concepts via the use of immunotherapy (colon, rectal cancer, UICC II/III). From liquid biopsies, ctDNA was associated with minimal residual disease, which influences disease-free survival. In the metastatic stage (UICC IV), tissue-based determination of RAS and BRAF V600E mutations, MSI‑H and in the near future also HER2/neu overexpression should be performed. Broader molecular diagnostics to optimize first-line therapy (molecular hyperselection) shows little additional benefit. ctDNA can be used for longitudinal monitoring of clonal tumor evolution or as an alternative to invasive diagnostics in patients.

CONCLUSIONS

Molecular pathological diagnostics from tissue and blood complement each other and should be used in a targeted and meaningful way according to the underlying question.