Zannoni Gian Franco, Angelico Giuseppe, d'Amati Antonio, D'Alessandris Nicoletta, Scaglione Giulia, Urtueta Belen Padial, Ferrara Gerardo, Caliò Anna, Campisi Paola, De Leo Antonio, Guerini Rocco Elena, Iuzzolino Martina, Lerda Lucia, Paolini Biagio, Punzi Alessandra, Vinci Mattia, Troncone Giancarlo, Santoro Angela
Pathology Unit, Department of Woman and Child's Health and Public Health Sciences, Fondazione Policlinico Universitario Agostino Gemelli IRCCS, Largo A. Gemelli 8, 00168 Rome, Italy.
Pathology Institute, Catholic University of Sacred Heart, 00168 Rome, Italy.
Int J Mol Sci. 2025 Aug 8;26(16):7687. doi: 10.3390/ijms26167687.
Folate receptor alpha (FRα) is a high-affinity folate transporter overexpressed in various epithelial malignancies, particularly high-grade serous ovarian carcinoma. Given its restricted expression in normal tissues and accessibility in tumors, FRα is an emerging therapeutic target. Immunohistochemistry (IHC) is the standard method for FRα assessment; however, interpretation is semi-quantitative and prone to interobserver variability. This study aimed to evaluate interobserver agreement among 12 pathologists in the IHC assessment of FRα in ovarian cancer, focusing on internal control adequacy, staining intensity, and the percentage of FRα-positive tumor cells. Thirty-seven high-grade serous ovarian carcinoma cases were stained using the VENTANA FOLR1 (FOLR1-2.1) RxDx Assay. A reference panel of four expert pathologists established consensus diagnoses. Twelve pathologists independently assessed the slides, recording internal control adequacy, staining intensity (positive vs. negative), and percentage of FRα-positive tumor cells. Interobserver agreement was measured using Fleiss' kappa and intraclass correlation coefficient (ICC). Agreement on internal control adequacy was almost perfect (κ = 0.84). Substantial agreement was observed for staining intensity (κ = 0.76), while percentage estimation showed almost perfect concordance (ICC = 0.89). Discrepancies were primarily confined to borderline cases (65-85% positivity) and tumors with intermediate staining, reflecting interpretive challenges near clinical decision thresholds. Pathologists demonstrated high reproducibility in FRα IHC assessment, particularly in estimating percentage positivity and control adequacy. These findings support the clinical utility of FRα IHC but underscore the need for standardized scoring criteria and potential integration of digital tools to enhance consistency, especially in borderline cases.
叶酸受体α（FRα）是一种高亲和力的叶酸转运蛋白，在各种上皮性恶性肿瘤中过度表达，尤其是高级别浆液性卵巢癌。鉴于其在正常组织中的表达受限以及在肿瘤中的可及性，FRα是一个新兴的治疗靶点。免疫组织化学（IHC）是评估FRα的标准方法；然而，其解读是半定量的，且容易出现观察者间的差异。本研究旨在评估12名病理学家在卵巢癌FRα的IHC评估中的观察者间一致性，重点关注内部对照的充分性、染色强度以及FRα阳性肿瘤细胞的百分比。使用VENTANA FOLR1（FOLR1-2.1）RxDx检测法对37例高级别浆液性卵巢癌病例进行染色。由四名专家病理学家组成的参考小组确定了共识诊断。12名病理学家独立评估切片，记录内部对照的充分性、染色强度（阳性与阴性）以及FRα阳性肿瘤细胞的百分比。使用Fleiss' kappa和组内相关系数（ICC）测量观察者间一致性。在内部对照充分性方面的一致性几乎完美（κ = 0.84）。在染色强度方面观察到高度一致性（κ = 0.76），而百分比估计显示几乎完全一致（ICC = 0.89）。差异主要局限于临界病例（阳性率65 - 85%）和染色中等的肿瘤，这反映了接近临床决策阈值时的解读挑战。病理学家在FRα IHC评估中表现出高度的可重复性，特别是在估计阳性百分比和对照充分性方面。这些发现支持了FRα IHC的临床实用性，但强调了需要标准化的评分标准以及可能整合数字工具以提高一致性，尤其是在临界病例中。
