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Utility of Commercially Available Quantitative hCG Immunoassays as Tumor Markers

Qing H. Meng, PhD, MD, DABCC, FADLM, Professor, Director of Clinical Chemistry and Special Chemistry Laboratories, Director of Postdoctoral Clinical Chemistry Fellowship Program, Department of Laboratory Medicine, MD Anderson Cancer Center, the University of Texas


Jieli Shirley Li, MD, PhD, DABCC, NRCC. Co-Director of Clinical Chemistry and Toxicology Laboratory, Wexner Medical Center, Assistant Professor of Pathology, the Ohio State University



Human chorionic gonadotropin (hCG) has long served as a valuable tool for diagnosing and monitoring both pregnancy and malignancy. However, despite its widespread use, hCG as a tumor marker has not been approved by FDA. As a glycoprotein hormone, hCG has various iso- and glycoforms. Depending on the different epitopes recognized by diverse antibodies, the commercially available hCG immunoassays exhibit wide inter-method variability. Through a multi-lab collaborative research, Dr. Meng and Dr. Li et. al. assessed the utility of commercially available quantitative hCG immunoassays as tumor markers in both trophoblastic and non-trophoblastic disease[1].

 

The study compared five quantitative hCG immunoassays, including Abbott Architect Total (detects intact hCG, hCGβ, hCGn, hCGβn), Roche Cobas STAT (intact hCG), Roche Cobas Total (intact hCG, hCGβ, hCGβcf, hCGn, hCGβn), Siemens Dimension Vista Total (intact hCG, hCGβ, hCGβcf, hCGn, hCGβn), and Beckman Access Total (intact hCG, hCGβ, hCGn, hCGβn). These assays were evaluated in a large cohort of patients (n=150) with gestational trophoblastic disease (GTD), germ cell tumors (GCT), or other malignancies (such as prostate, breast, colorectal, ovarian, lung, or other). Elevated hCG levels, exceeding reference cutoffs, were detected in all specimens obtained from patients with GTD, in 55% to 57% of patients with GCT, and 8% to 23% of patients with non-trophoblastic disease. Among the five immunoassays, the Roche Cobas Total detected elevated hCG in the greatest number of specimens (63/150), followed closely by the Beckman Access (62/150). Detection of elevated hCG in trophoblastic disease was nearly equivalent among all five immunoassays, ranging from 41 to 42 out of 60 specimens. Using a cutoff of 25 IU/L, only 7 out of 150 specimens exhibited divergent results between methods, and all of them were from patients with non-trophoblastic diseases. Additionally, the study compared total vs. STAT hCG (intact hCG only) to roughly estimate the level of hCG-β in non-trophoblastic cancers. The estimated percentage of relative hCG-β among specimens varied widely ranging from 5.3 to > 99%.

 

The findings of this study suggest that all five hCG immunoassays are adequate for use of hCG as a tumor marker in GTD and selected GCT, and inconsistent detection of elevated hCG is primarily observed in non-trophoblastic disease. As hCG is yet to be approved as a tumor marker, the inter-method comparison and the investigation into different tumor types provide paramount clinical values for its application in malignancy. Due to its clinical significance, this work was published in Clinical Chemistry.



定量hCG免疫检测法作为肿瘤标志物的效用

 

人绒毛膜促性腺激素(hCG)长期以来被广泛应用于妊娠和恶性肿瘤的诊断和监测。尽管其被广泛使用,hCG作为肿瘤标志物的应用尚未获得FDA的批准。作为一种糖蛋白激素,hCG存在各种不同的同工型和糖基形式。由于不同抗体识别不同的抗原表位,hCG的免疫测定方法间存在很大的差异。孟博士、李博士等人参与一项多中心研究,对常用hCG定量免疫检测方法在滋养细胞疾病和非滋养细胞疾病中作为肿瘤标志物的效用进行了评估[1] 。

 

该研究比较了五种常用 hCG 定量免疫检测方法,包括 Abbott Architect Total (检测完整 hCG, hCGβ, hCGn, hCGβn)、Roche Cobas STAT (完整 hCG)、Roche Cobas Total (完整 hCG, hCGβ, hCGβcf, hCGn, hCGβn)、Siemens Dimension Vista Total (完整 hCG, hCGβ, hCGβcf, hCGn, hCGβn) 和 Beckman Access Total (完整 hCG, hCGβ, hCGn, hCGβn)。 该研究在一个大型病例组中对这五种 hCG 方法进行评估(n=150),其中包括妊娠滋养细胞疾病(GTD)、生殖细胞瘤(GCT)或其他恶性肿瘤(前列腺、乳腺、结直肠、卵巢、肺等)。所有来自 GTD 患者的标本中均检测到了 hCG 的升高(超过参考范围),在 GCT 患者中有 55-57% 的标本检测到 hCG 的升高,而在非滋养细胞疾病患者中检测到 8-23% 的标本存在 hCG 的升高。总体而言,Roche Cobas Total 检测到 hCG 升高的标本数最多(63/150),紧随其次是 Beckman Access(62/150)。在滋养细胞疾病中,所有免疫测定方法检测到的 hCG 升高几乎是相等的(范围为41-42/60)。以 25 IU/L 为临界值,只有7/150 个标本在不同方法之间出现了不一致的结果,而所有这些标本均来自非滋养细胞疾病的患者。此外,他们还比较了总 hCG 与 STAT hCG(Roche)以粗略估算 hCG-β 的水平。据此推算的 hCG-β 的百分比在标本中差异很大,范围从 5.3% 到超过 99%。

 

该研究的结果表明,所有五种 hCG 免疫检测方法在 GTD 和一些特定的 GCT 中以 hCG 为肿瘤标志物是适用的,但在非滋养细胞疾病中 hCG 的升高与否存在差异, 其应用有待商榷。目前 hCG 作为肿瘤标志物仍有待 FDA 批准,不同方法间的比较以及在不同肿瘤类型中的水平为其在肿瘤诊断的应用中提供了至关重要的临床价值。鉴于其重大的临床意义,这项工作已发表在《临床化学》杂志上。

 

 

Reference:

 

1.         Franks, C.E., et al., Utility of Commercially Available Quantitative hCG Immunoassays as Tumor Markers in Trophoblastic and Non-Trophoblastic Disease. Clin Chem, 2023.


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