Molecular phenotyping of colorectal tumors in clinical practice: Assignment of extended prognostic subtypes by direct testing of endoscopic specimens
Abstrakt
Introduction: Since the pioneering work of Fearon and Vogelstein in 1990, detailed mechanisms of colorectal neoplasia have intensively been studied (1). Only recently, however, importance of molecular subtypes for prognosis has been confirmed on large cohorts (2,3).
The so-called Jass classification is set to become an part of diagnostics complementary to the companion predictive genotyping (4). The diagnosis is mostly based on examination of tumor tissue from endoscopy.
It was an intention of this work to evaluate feasibility of molecular phenotyping in addition to the standard testing performed from the same source material. Patients and Methods: A total of 145 carcinomas (105 fresh biopsies or 40 FFPE sections, all stages) have been acquired over a 3-year period.
The molecular subtypes were assigned based upon results of CIMP/MSI/BRAF/RAS (5). To partition the most common type arising from traditional adenoma-carcinoma pathway, we have additionally examined MLH1 methylation and APC and TP53 mutations (6).
The methodology was based on previously validated protocols including MS-MLPA for the evaluation of CIMP, PCR fragment analysis MSI and high-sensitive denaturing CE assay (DCE) for somatic mutations in RAS, BRAF, TP53 and APC genes.