Methylator phenotype in colorectal cancer: A prognostic factor or not?

ABSTRACT

Colorectal cancer (CRC) is due to different types of genetic alterations that are translated into different phenotypes. Among them, CpG island methylator phenotype (CIMP+) is the most recently involved in carcinogenesis of some CRC. The malignant transformation in this case is mainly due to the transcriptional inactivation of tumor suppressor genes. CIMP+ are reported to be more frequently found in the elderly and in women. The tumors are more frequently located in the proximal part of the colon, BRAF mutated and are associated with microsatellite instability (MSI) phenotype. All sporadic MSI CRC belong to the methylator phenotype, however some non MSI CRC may also harbor a methylator phenotype. The prognostic value of CIMP is not well known. Most studies show a worse prognosis in CIMP+ CRC, and adjuvant treatments seem to be more efficient. We review here the current knowledge on prognostic and predictive values in CIMP+ CRC.