2.5. Article Selection

Published articles on circulating miRNAs associated with cancer were selected on PubMed by searching for “serum miRNAs”, “serum microRNAs”, “plasma miRNAs”, “plasma microRNAs”, “circulating miRNAs”, “circulating microRNAs” with “cancer diagnosis” for five cancers: lung cancer (LC), prostate cancer (PC), colon cancer (CC), liver cancer (HC) and gastroesophageal cancer (GEC) and related subtypes. These cancers were chosen as the five most frequent cancers in males worldwide, according to the “Global Cancer Observatory” (https://gco.iarc.fr/, accessed on 31 December 2020), for which exist evidence, through meta-analysis (published from 2010 to 2020), on association with physical activity (all-cancer risk/mortality [25,26,27,28,29]; LC [30,31]; PC [32]; CC [33,34,35]; HC [36]; GEC [37,38,39,40,41,42,43,44,45]). Only studies on human, published from 2010, and demonstrating a clinical relevance for single serum/plasma miRNA or serum/plasma miRNA signatures including at least one of the modulated miRNAs in our trained cohort were considered. The clinical relevance was defined only in the presence of a literature-derived ROC curve analysis resulting in an area under curve (AUC) >0.7, for diagnostic purpose [46]. This search referred to all 179 analyzed miRNAs.