Ahmed Farid E
Institute for Research in Biotechnology, GEM Tox Labs, 2607 Calvin Way, Greenville, NC 27834, USA.
Expert Rev Anticancer Ther. 2014 Apr;14(4):463-85. doi: 10.1586/14737140.2014.869479. Epub 2014 Mar 3.
Early screening for colon cancer (CC) allows for early stage diagnosis of the malignancy and potentially reduces disease mortality as the cancer is most likely curable at its earliest stages. Early detection would be desirable if accurate, practical and cost-effective diagnostic measures for this cancer were available. Mortality and morbidity from CC represent a major health problem involving a malignant disease that is theoretically preventable through screening. Current screening methods (e.g., the convenient and inexpensive immunological fecal occult blood test, FOBTi, obtained from patients' medical records) either lack sensitivity and require dietary restriction, which impedes compliance and use; are costly (e.g., colonoscopy), which decreases compliance; or could result in mortality. In comparison with the FOBT test, a non-invasive sensitive screen for which there is no requirement for dietary restriction would be a more convenient test. Colorectal cancer is the only cancer for which colonoscopy is recommended as a screening method. Although colonoscopy is a reliable screening tool, the invasive nature, abdominal pain, potential complications and high cost have hampered the application of this procedure worldwide. A screening approach using the stable miRNA molecules, which are relatively non-degradable when extracted from non-invasive stool and semi-invasive blood samples by commercially available kits and manipulated thereafter, would be preferable to a transcriptomic mRNA-, a mutation DNA-, an epigenetic- or a proteomic-based test. The approach uses reverse transcriptase, modified real-time quantitative PCR. Although exosomal RNA would be missed, using a restricted extraction of total RNA from stool or blood, a parallel test could also be carried out on RNA obtained from stool or plasma samples, and appropriate corrections for exsosomal loss can be made for accurate and quantitative test result. Eventually, a chip can be developed to facilitate diagnosis, as has been done for the quantification of genetically modified organisms in foods. The gold standard to which the molecular miRNA test is compared is colonoscopy, which can be obtained from patients' medical records. If performance criteria are met, as detailed herein, a miRNA test in human stool or blood samples based on high-throughput automated technologies and quantitative expression measurements commonly used in the diagnostic clinical laboratory should be advanced to the clinical setting, which will make a significant impact on CC prevention.
结肠癌（CC）的早期筛查有助于对这种恶性肿瘤进行早期诊断，并有可能降低疾病死亡率，因为癌症在最早期阶段最有可能治愈。如果能有针对这种癌症的准确、实用且具有成本效益的诊断措施，那么早期检测将是很理想的。CC导致的死亡率和发病率是一个重大的健康问题，涉及一种理论上可通过筛查预防的恶性疾病。目前的筛查方法（例如，从患者病历中获取的方便且廉价的免疫粪便潜血试验，FOBTi）要么缺乏敏感性且需要饮食限制，这会妨碍其依从性和应用；要么成本高昂（例如结肠镜检查），这会降低依从性；或者可能导致死亡。与FOBT试验相比，一种无需饮食限制的非侵入性敏感筛查将是更方便的检测方法。结直肠癌是唯一推荐将结肠镜检查作为筛查方法的癌症。虽然结肠镜检查是一种可靠的筛查工具，但其侵入性、腹痛、潜在并发症和高成本阻碍了该检查在全球范围内的应用。使用稳定的miRNA分子的筛查方法将比基于转录组mRNA、突变DNA、表观遗传学或蛋白质组学的检测更可取，这些miRNA分子在通过市售试剂盒从非侵入性粪便和半侵入性血液样本中提取并随后进行处理时相对不易降解。该方法使用逆转录酶、改良的实时定量PCR。虽然外泌体RNA会被遗漏，但通过对粪便或血液中的总RNA进行有限提取，可以对从粪便或血浆样本中获得的RNA同时进行检测，并可以对外泌体损失进行适当校正以获得准确的定量检测结果。最终，可以开发一种芯片来促进诊断，就像对食品中基因改造生物的定量检测那样。与分子miRNA检测进行比较的金标准是结肠镜检查，其结果可从患者病历中获取。如果满足本文详述的性能标准，那么基于诊断临床实验室常用的高通量自动化技术和定量表达测量的人粪便或血液样本中的miRNA检测应推进到临床应用中，这将对CC的预防产生重大影响。
