Telomere length as a prognostic marker in colorectal cancer: a scoping review

Abstract

Background: Telomeres are protective structures at both ends of a chromosome, which consist of repetitive DNA sequences (TTAGGG). Maintenance of telomere length is known to have important roles in carcinogenesis. However, there is no consensus about the prognostic role of telomere length in colorectal cancer. Methods: We conducted a scoping review using Pubmed and EMBASE as information sources through April 2019. Inclusion criteria were studies investigating telomere length and prognosis of colorectal cancer. Selected studies were reviewed to reevaluate the significance of telomere length in the prognosis of colorectal cancer. The aim of the study was to summarize the previous studies, to find consistent results, and to suggest future research. Results: In total, 12 studies were identified and 1955 patients were included from 2004 to 2019. Among 10 studies with tissue samples, two studies revealed better prognosis in patients with longer telomere length, and only stage IV patients were recruited in these two studies; four studies revealed better prognosis in patients with shorter telomere length or lower ratio of telomere length between cancer and normal tissue; four studies did not show any significant association between tumor length and prognosis. Two studies with blood samples presented contradictory results regarding the correlation between telomere length and survival rate. Conclusions: There was no consistent evidence to prove the prognostic value of telomere length in colorectal cancer. However, in a subgroup with the metastatic disease only, longer telomere length of tumor tissue was significantly associated with superior prognosis. Multicenter prospective studies with a large sample size are needed to verify the prognostic value of telomere length in colorectal cancer.