Abstract
Colorectal cancer patients’ responses to neoadjuvant therapy undergo broad inter-individual variations. The aim of this systematic review is to identify a molecular signature that is predictive of colon cancer downstaging and/or downgrading after neoadjuvant therapy. Among the hundreds analysed in the available studies, only 19 messenger-RNAs (mRNAs) and six micro-RNAs (miRNAs) were differentially expressed in responders versus non-responders in two or more independent studies. Therefore, a mRNA/miRNA signature can be designed accordingly, with limitations caused by the retrospective nature of these studies, the heterogeneity in study designs and the downgrading/downstaging assessment criteria. This signature can be proposed to tailor neoadjuvant therapy regimens on an individual basis.
Highlights
Colorectal cancer (CRC) represents the second most common cancer in the world, with an estimated number of prevalent cases (1-year) in 2018 of 1,356,151; the prevalence estimates for 2018 were computed using sex, site, and age-specific ratios of incidence to 1-year prevalence from Nordic countries for the period 2000–2009; these ratios were scaled using Human Development Index (HDI)ratios
We developed a search strategy and adapted it for each database, using a combination of the following keywords: colorectal cancer, rectal cancer, response, sensitivity, resistance, neoadjuvant, pretreatment, preoperative, chemoradiation, chemoradiotherapy, radiochemotherapy, chemotherapy, radiotherapy, gene expression, gene expression profile, gene expression profiling, microarray, array, polymerase chain reaction, genetic signature, transcriptomic, transcriptional, biomarkers, molecular markers, molecular response; colorectal neoplasms, gene expression, neoadjuvant therapy and chemoradiotherapy, applied as MeSH-terms
Searchand miRNA expression data were extracted from the manuscript and Genes
Summary
Colorectal cancer (CRC) represents the second most common cancer in the world, with an estimated number of prevalent cases (1-year) in 2018 of 1,356,151; the prevalence estimates for 2018 were computed using sex-, site-, and age-specific ratios of incidence to 1-year prevalence from Nordic countries for the period 2000–2009; these ratios were scaled using Human Development Index (HDI). The estimated number of incident cases worldwide (per year) is 1,849,518 [1]. The 5-year survival reaches 90% when the cancer is diagnosed at the localized stage of the disease, but this situation occurs only for 39% of CRC patients. When CRC is diagnosed in the regional stages, 5-year survival is reduced to 71%, while the reduction reaches up to 14% in patients in distant stages [2]. Less frequent than colon cancer, it seems to have many similar features to colon cancer in terms of geographic distribution
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