title: Colorectal Cancer: Personalized Therapy.
abstract: BACKGROUND
  Colorectal cancer (CRC) is the second most common type of cancer in the Western world. The treatment of this disease has evolved greatly, particularly for patients with metastatic disease. The advent of combination chemotherapy plus targeted agents has led to more curative resections and improved survival rates in these patients. A deeper understanding of the mechanisms of tumorigenesis has facilitated tumor characterization, prognosis and patient stratification, bringing us one step closer towards personalized medicine.
  
  
  CONCLUSIONS
  There are two main pathways of CRC development: (1) chromosomal instability, also known as the classical adenoma-carcinoma sequence, and (2) microsatellite instability, caused by a defective mismatch repair (dMMR) system. Analysis of these pathways has uncovered key prognostic and predictive biomarkers to guide patient selection and treatment strategy. This review summarizes the current treatment regimens and recent advances in the personalized therapy of CRC.
  
  
  CONCLUSIONS
  Understanding of the mechanisms of CRC pathogenesis has led to new developments in tumor characterization, patient stratification, prognosis and treatment, bringing us closer to personalized therapy.
  
  
  CONCLUSIONS
  In the adjuvant setting, the treatment decision is driven by clinical and histopathological factors. dMMR status is one of the most robust positive prognostic factors in resected colon cancer. More and more guidelines recommend refraining from adjuvant chemotherapy in patients with dMMR. In the metastatic setting, the introduction of effective compounds, including agents that target the epidermal growth factor receptor and vascular endothelial growth factor pathways, has significantly improved survival. The presence of wild-type KRAS and NRAS (all RAS) is a positive predictive factor for epidermal growth factor receptor antibody treatment. Therefore, analysis of all RAS status is recommended for all patients with metastatic disease prior to the initiation of first-line chemotherapy.
authors.affiliation: Division of Hematology and Oncology, Department of Medicine I, St. Josef-Hospital, University Hospital, Ruhr University Bochum, Bochum, Germany.
authors.forename: Jona
authors.initials: J
authors.lastname: Leichsenring
authors.affiliation: Division of Hematology and Oncology, Department of Medicine I, St. Josef-Hospital, University Hospital, Ruhr University Bochum, Bochum, Germany.
authors.forename: Adrian
authors.initials: A
authors.lastname: Koppelle
authors.affiliation: Division of Hematology and Oncology, Department of Medicine I, St. Josef-Hospital, University Hospital, Ruhr University Bochum, Bochum, Germany.
authors.forename: Ank
authors.initials: A
authors.lastname: Reinacher-Schick
keywords: Adjuvant therapy; Colorectal cancer; Microsatellite instability; Palliative therapy; Personalized therapy