[Molecular testing and liquid biopsies in colorectal cancer].

Abstract

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.