Abstract

Fragments of cell-free DNA (cfDNA) in human body fluids often carry disease-specific alterations and are now widely recognized as ideal biomarkers for the detection and monitoring of genomic disorders, especially cancer, that are normally difficult to examine noninvasively. However, the conversion of promising research findings into tools useful in routine clinical testing of cancer has been a slow-moving process. A major reason is that the diagnostic sensitivity and specificity of cfDNA-based clinical assays are negatively impacted by a combination of suboptimal and inter-institutional differences in preanalytical procedures. The most prominent factors include: (i) a poor understanding of the biological factors that determine the characteristics of the cfDNA population in a biospecimen prior to collection, (ii) inattention to how cfDNA with different structures and physical properties are affected differently by a given preanalytical step, and (iii) the sheer number of possible conditions that can be selected from for each preanalytical step along with a continually expanding menu of commercial products that often show varying degrees of bias and efficiency. The convergence of these variables makes it difficult for research groups and institutions to reach a consensus on optimal preanalytical procedures and a challenging task to establish widely applied standards, which ultimately hamper the development of cfDNA assays that are fit for broad clinical implementation. In this review, we follow a systematic approach to explore the most confounding preanalytical factors that affect the outcome of cfDNA measurements.

摘要

人体体液中的无细胞DNA（cfDNA）片段通常带有疾病特异性的变化，现已被广泛认为是检测和监测基因组疾病（尤其是癌症）的理想生物标志物，通常很难以无创方式对其进行检查。然而，将有前途的研究成果转换成可用于癌症常规临床测试的工具一直是一个缓慢的过程。一个主要原因是，基于cfDNA的临床检测方法的诊断敏感性和特异性受到分析前程序中次优和机构间差异的共同影响。最突出的因素包括：（i）对决定收集前生物样本中cfDNA种群特征的生物学因素了解不足，（ii）对给定的分析前步骤对具有不同结构和物理特性的cfDNA的影响有所不同，以及（iii）可以从每个分析前步骤中选择的可能条件的绝对数量，以及商业产品菜单的不断扩展常常表现出不同程度的偏见和效率。这些变量的趋同使得研究小组和机构难以就最佳的分析前程序达成共识，也难以建立广泛应用的标准，这最终阻碍了适合广泛临床实施的cfDNA分析方法的发展。在这篇综述中，我们遵循一种系统的方法来探索影响cfDNA测量结果的最复杂的分析前因素。