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Background: Circulating microRNAs (miRNAs) have become reliable sources of non‐invasive biomarkers for cancer diagnosis. Identification of promising miRNA biomarkers in plasma might benefit a lot to the detection of nasopharyngeal carcinoma (NPC). Methods: The Exiqon miRNA qPCR panel was used in the screening stage to identify candidate miRNAs, which were further verified by quantitative reverse transcription polymerase chain reaction (qRT‐PCR) in the following three stages among plasma samples from 200 NPC patients and 189 healthy donors (as normal controls [NCs]). The identified miRNAs were further explored in tissue specimens (48 NPC vs 32 NCs) and plasma exosomes (32 NPC vs 32 NCs). Survival analyses were ultimately conducted by Cox regression models and Kaplan‐Meier curves using log‐rank tests. Results: We identified a 7‐miRNA signature including let‐7b‐5p, miR‐140‐3p, miR‐144‐3p, miR‐17‐5p, miR‐20a‐5p, miR‐20b‐5p, and miR‐205‐5p in plasma for NPC diagnosis after four‐stage validation. The areas under the receiver operating characteristic curve (AUCs) for the signature were 0.879, 0.884, 0.921, and 0.807 for the training, testing, external validation stage, and the combined three stages, respectively. In NPC tissues, miR‐144‐3p, miR‐17‐5p, miR‐20a‐5p, and miR‐205‐5p were consistently up‐regulated while let‐7b‐5p and miR‐140‐3p were significantly down‐regulated compared to NCs. However, none of the seven identified miRNAs were dysregulated in plasma‐derived exosomes in NPC patients. As to survival analysis, none of the seven miRNAs seemed to be associated with NPC prognosis. Conclusion: We identified a 7‐miRNA signature in plasma as promising non‐invasive biomarkers for NPC detection. [ABSTRACT FROM AUTHOR]

Breast cancer (BC) is one of the most common cancers in females. Since early detection can bring prognosis benefit, discovery of novel noninvasive biomarkers for BC diagnosis is in urgent need. In this four‐phase study, we profiled miRNA expression in plasma samples from a total of 257 BC patients and 257 normal controls (NCs). Exiqon miRNA qPCR panel was used to select candidate miRNAs in the screening phase which were further analyzed using qRT‐PCR in the following training, testing and external validation phases. Finally, we identified five plasma miRNAs (let‐7b‐5p, miR‐122‐5p, miR‐146b‐5p, miR‐210‐3p and miR‐215‐5p) whose expression levels were significantly different between BC patients and NCs. A 5‐miRNA panel in plasma with high sensitivity and specificity was then constructed to detect BC. The areas under the receiver‐operating characteristic curves (AUCs) of the panel were 0.683, 0.966, 0.978 for the training, testing and external validation sets, respectively. Expression of the identified miRNAs was further analyzed among 32 pairs of BC tissue and the adjacent normal tissue samples as well as plasma‐derived exosome samples from 32 BC patients vs 32 NCs. Let‐7b‐5p was contrarily down‐regulated in BC tissue. In exosomes samples, only miR‐122‐5p was significantly up‐regulated as in plasma for BC patients. In conclusion, we identified a 5‐miRNA plasma panel (let‐7b‐5p, miR‐122‐5p, miR‐146b‐5p, miR‐210‐3p and miR‐215‐5p) that could serve as a promising biomarker for BC detection. [ABSTRACT FROM AUTHOR]