Is Precision Surgery Applicable to Colorectal Liver Metastases? A Systematic Review and Meta-analysis of Studies that Investigate the Association of Surgical Technique with Outcomes in the Context of Distinct Tumor Biology

Molecular characterization of the histopathological growth patterns of colorectal cancer liver metastases by RNA sequencing of targeted samples at the tumor-liver interface

The behaviour of metastases in patients with liver-metastatic colorectal cancer (CRC) is still not adequately considered during treatment planning. However, studies in large cohorts have shown that the disease course in these patients depends on the histopathological growth pattern (HGP) of the liver metastases, with the desmoplastic (or encapsulated) pattern responsible for a favourable outcome and the replacement pattern for an unfavourable course. To increase our knowledge of cancer biology in general as well as to design clinical trials that take into account the diverse behaviour of liver metastases, it is necessary to know the cellular and molecular determinants of these growth patterns. For that purpose, we compared the transcriptome of tumour tissue (prospective cohort; n = 57) sampled very precisely at the transition of metastasis and adjacent liver, between the desmoplastic and replacement HGP. In addition, the mutational profiles for 46 genes related to CRC were extracted from the RNA sequencing reads. First, we show that the genetic constitution of a liver metastasis from colorectal cancer does not determine its HGP. Second, we show clear differences between HGPs regarding the expression of genes belonging to the Molecular Signatures Database hallmark gene sets. Biological themes of the replacement HGP reflect cancer cell proliferation and glucose metabolism, while the desmoplastic HGP is characterized by inflammation and immune response, and angiogenesis. This study supports the view that HGPs are a reflection of the biology of CRC liver metastases and suggests the HGPs are driven epigenetically rather than by specific gene mutations.

Somatic Mutations in Surgically Treated Colorectal Liver Metastases: An Overview

Colorectal cancer is the second most common cause of cancer death in the United States, and up to half of patients develop colorectal liver metastases (CRLMs). Notably, somatic genetic mutations, such as mutations in RAS, BRAF, mismatch repair (MMR) genes, TP53, and SMAD4, have been shown to play a prognostic role in patients with CRLM. This review summarizes and appraises the current literature regarding the most relevant somatic mutations in surgically treated CRLM by not only reviewing representative studies, but also providing recommendations for areas of future research. In addition, advancements in genetic testing and an increasing emphasis on precision medicine have led to a more nuanced understanding of these mutations; thus, more granular data for each mutation are reviewed when available. Importantly, such knowledge can pave the way for precision medicine with the ultimate goal of improving patient outcomes.