Early-stage colorectal carcinoma (CRC)—pT1—is a therapeutic challenge and presents some histological features related to lymph node metastasis (LNM). A significant proportion of pT1 CRCs are treated surgically, resulting in a non-negligible surgical-associated mortality rate of 1.5–2%. Among these cases, approximately 6–16% exhibit LNM, but the impact on survival is unclear. Therefore, there is an unmet need to establish an objective and reliable lymph node (LN) staging method to optimise the therapeutic management of pT1 CRC patients and to avoid overtreating or undertreating them. In this multicentre study, 89 patients with pT1 CRC were included. All histological features associated with LNM were evaluated. LNs were assessed using two methods, One-Step Nucleic Acid Amplification (OSNA) and the conventional FFPE plus haematoxylin and eosin (H&E) staining. OSNA is an RT-PCR-based method for amplifying CK19 mRNA. Our aim was to assess the performance of OSNA and H&E in evaluating LNs to identify patients at risk of recurrence and to optimise their clinical management. We observed an 80.9% concordance in LN assessment using the two methods. In 9% of cases, LNs were found to be positive using H&E, and in 24.7% of cases, LNs were found to be positive using OSNA. The OSNA results are provided as the total tumour load (TTL), defined as the total tumour burden present in all the LNs of a surgical specimen. In CRC, a TTL ≥ 6000 CK19 m-RNA copies/µL is associated with poor prognosis. Three patients had TTL > 6000 copies/μL, which was associated with higher tumour budding. The discrepancies observed between the OSNA and H&E results were mostly attributed to tumour allocation bias. We concluded that LN assessment with OSNA enables the identification of pT1 CRC patients at some risk of recurrence and helps to optimise their clinical management.
早期结直肠癌（pT1期）在治疗上具有挑战性，其某些组织学特征与淋巴结转移相关。相当一部分pT1期结直肠癌患者接受手术治疗，导致1.5%-2%不可忽视的手术相关死亡率。在这些病例中，约6%-16%存在淋巴结转移，但其对生存率的影响尚不明确。因此，当前亟需建立客观可靠的淋巴结分期方法，以优化pT1期结直肠癌患者的治疗管理，避免过度治疗或治疗不足。本多中心研究纳入89例pT1期结直肠癌患者，评估了所有与淋巴结转移相关的组织学特征。采用一步核酸扩增技术（OSNA）和传统福尔马林固定石蜡包埋联合苏木精-伊红染色两种方法进行淋巴结评估。OSNA是一种基于RT-PCR技术扩增CK19 mRNA的方法。本研究旨在评估两种方法在淋巴结检测中的效能，以识别复发风险患者并优化临床管理。两种方法的淋巴结评估一致性达80.9%。9%的病例通过H&E染色检测到淋巴结阳性，而OSNA检测的阳性率为24.7%。OSNA结果以总肿瘤负荷呈现，定义为手术标本所有淋巴结中肿瘤负荷总量。在结直肠癌中，TTL≥6000 CK19 mRNA拷贝数/微升提示预后不良。3例患者TTL>6000拷贝数/微升，该指标与较高肿瘤出芽程度相关。OSNA与H&E结果的差异主要归因于肿瘤分布偏倚。本研究结论：OSNA淋巴结评估能够识别具有复发风险的pT1期结直肠癌患者，有助于优化临床治疗决策。
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