Department of Laboratory Medicine, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Republic of Korea.
Department of Surgery and Cancer Research Institute, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Republic of Korea.
Clin Chem. 2022 Dec 6;68(12):1509-1518. doi: 10.1093/clinchem/hvac153.
Circulating tumor DNA (ctDNA) is a promising biomarker for early tumor detection and minimal residual disease (MRD) assessment in early-stage cancer, but quantifying minute amounts of ctDNA is challenging and well-designed studies on ctDNA in early-stage cancer are still lacking. Here, we adapted a sensitive next-generation sequencing (NGS) technology and performed parallel analysis of pre- and postoperative ctDNA and matched tumor tissues in a prospective cohort of patients with resectable pancreatic ductal adenocarcinoma (PDAC).
In total, 70 consecutive patients undergoing curative resection for resectable PDAC were enrolled. We performed integrated digital error suppression-enhanced cancer personalized profiling by deep sequencing NGS of triple-matched samples (pre/postoperative plasma cell-free DNA [cfDNA], tumor tissue, and genomic DNA) targeting 77 genes.
Preoperative ctDNA was detected in 37.7% of the evaluable patients, with a median variant allele frequency of 0.09%. Twelve additional oncogenic mutations were detected exclusively in preoperative ctDNA but not in tissue. When quantitative concentrations of ctDNA were estimated in haploid genome equivalents per milliliter (hGE/mL), the risk of early recurrence was high in patients with postoperative ctDNA >1 hGE/mL. cfDNA variants from 24.5% of patients had features compatible with clonal hematopoiesis.
An optimized NGS approach might add value beyond tissue analysis through the highly sensitive detection of minute amounts of ctDNA in resectable PDAC. Postoperative ctDNA concentration could be a tool for MRD assessment. Moreover, parallel analyses of matched tissues and leukocytes might be required to accurately detect clinically relevant ctDNA.
循环肿瘤 DNA（ctDNA）是早期肿瘤检测和早期癌症微小残留病灶（MRD）评估的有前途的生物标志物，但定量检测微量 ctDNA 具有挑战性，并且针对早期癌症的 ctDNA 的精心设计研究仍然缺乏。在这里，我们采用了一种灵敏的下一代测序（NGS）技术，并在可切除胰腺导管腺癌（PDAC）的前瞻性队列患者中对术前和术后 ctDNA 以及匹配的肿瘤组织进行了平行分析。
总共纳入了 70 名接受可切除 PDAC 根治性切除术的连续患者。我们对三重匹配样本（术前/术后血浆无细胞 DNA [cfDNA]、肿瘤组织和基因组 DNA）进行了深度测序 NGS 的集成数字误差抑制增强癌症个体化分析，靶向 77 个基因。
可评估患者中有 37.7%检测到术前 ctDNA，中位变异等位基因频率为 0.09%。在组织中未检测到 12 个额外的致癌突变，但仅在术前 ctDNA 中检测到。当以每毫升单倍体基因组当量（hGE/mL）估计 ctDNA 的定量浓度时，术后 ctDNA >1 hGE/mL 的患者早期复发风险较高。来自 24.5%患者的 cfDNA 变体具有与克隆性造血相一致的特征。
通过在可切除 PDAC 中高度灵敏地检测微量 ctDNA，优化的 NGS 方法可能会超越组织分析。术后 ctDNA 浓度可能是 MRD 评估的一种工具。此外，可能需要对匹配的组织和白细胞进行平行分析，以准确检测临床相关的 ctDNA。
