*Department of Anatomical Pathology †Northern Cancer Translational Research Unit ††Familial Cancer Clinic, Royal North Shore Hospital ∥Department of Pathology, SYDPATH, St Vincents Hospital, Darlinghurst ¶Faculty of Medicine, University of NSW ¶¶Sydney Medical School, University of Sydney, Sydney, NSW §§Department of Molecular and Cellular Pathology ‡Department of Pathology, School of Medicine, University of Queensland ‡‡Envoi Specialist Pathologists, Herston §Cancer and Population Studies Group, Queensland Institute of Medical Research, Brisbane, QLD ∥∥Centre for Molecular, Environmental, Genetic and Analytic Epidemiology, School of Population Health, University of Melbourne, Carlton, Vic., Australia #Department of Neuropathology, Institute of Pathology, Ruprecht-Karls University **Clinical Cooperation Unit Neuropathology, German Cancer Research Center (DKFZ), Heidelberg, Germany.
Am J Surg Pathol. 2013 Oct;37(10):1592-602. doi: 10.1097/PAS.0b013e31828f233d.
BRAFV600E mutation in microsatellite-unstable (MSI) colorectal carcinomas (CRCs) virtually excludes Lynch syndrome (LS). In microsatellite-stable (MSS) CRCs it predicts poor prognosis. We propose a universal CRC LS screening algorithm using concurrent reflex immunohistochemistry (IHC) for BRAFV600E and mismatch-repair (MMR) proteins. We compared BRAFV600E IHC with multiplex polymerase chain reaction (PCR) and matrix-assisted laser desorption/ionization-time of flight mass spectrometry in 216 consecutive CRCs from 2011. Discordant cases were resolved with real-time PCR. BRAFV600E IHC was performed on 51 CRCs from the Australasian Colorectal Cancer Family Registry (ACCFR), which were fully characterized for BRAF mutation by allele-specific PCR, MMR status (MMR IHC and MSI), MLH1 promoter methylation, and germline MLH1 mutation. We then assessed MMR and BRAFV600E IHC on 1403 consecutive CRCs. By matrix-assisted laser desorption/ionization-time of flight mass spectrometry 15 cases did not yield a BRAF result, whereas 38/201 (19%) were positive. By IHC 45/216 (20%) were positive. Of the 7 discordant cases, real-time PCR confirmed the IHC result in 6. In the 51 CRCs from the ACCFR, IHC was concordant with allele-specific PCR in 50 cases. BRAFV600E and MSI IHC on 1403 CRCs demonstrated the following phenotypes: BRAF/MSS (1029 cases, 73%), BRAF/MSS (98, 7%), BRAF/MSI (183, 13%), and BRAF/MSI (93, 7%). All 11/1403 cancers associated with proven LS were BRAF/MSI. We conclude that BRAF IHC is highly concordant with 2 commonly used PCR-based BRAFV600E assays; it performed well in identifying MLH1 mutation carriers from the ACCFR and identified all cases of proven LS among the 1403 CRCs. Reflex BRAFV600E and MMR IHC are simple cheap tests that facilitate universal LS screening and identify the poor prognosis of the BRAFV600E-mutant MSS CRC phenotype.
BRAFV600E 突变在微卫星不稳定（MSI）结直肠癌（CRC）中几乎排除林奇综合征（LS）。在微卫星稳定（MSS）CRC 中，它预示着不良预后。我们提出了一种使用同时进行的免疫组织化学（IHC）检测 BRAFV600E 和错配修复（MMR）蛋白的通用 CRC LS 筛选算法。我们比较了 BRAFV600E IHC 与 2011 年连续 216 例 CRC 的多重聚合酶链反应（PCR）和基质辅助激光解吸/电离飞行时间质谱。通过实时 PCR 解决了不一致的病例。对来自澳大利亚结直肠癌家族登记处（ACCFR）的 51 例 CRC 进行了 BRAFV600E IHC 检测，这些 CRC 均通过等位基因特异性 PCR、MMR 状态（MMR IHC 和 MSI）、MLH1 启动子甲基化和种系 MLH1 突变对 BRAF 突变进行了充分特征分析。然后，我们对 1403 例连续 CRC 进行了 MMR 和 BRAFV600E IHC 检测。基质辅助激光解吸/电离飞行时间质谱检测 15 例未得到 BRAF 结果，而 38/201（19%）为阳性。IHC 检测 45/216（20%）为阳性。在 7 例不一致的病例中，实时 PCR 证实了 6 例 IHC 结果。在来自 ACCFR 的 51 例 CRC 中，IHC 与等位基因特异性 PCR 在 50 例中一致。在 1403 例 CRC 上进行 BRAFV600E 和 MSI IHC 显示了以下表型：BRAF/MSS（1029 例，73%）、BRAF/MSS（98 例，7%）、BRAF/MSI（183 例，13%）和 BRAF/MSI（93 例，7%）。所有与证实的 LS 相关的 11/1403 例癌症均为 BRAF/MSI。我们得出结论，BRAF IHC 与两种常用的基于 PCR 的 BRAFV600E 检测高度一致；它在从 ACCFR 中识别 MLH1 突变携带者方面表现良好，并在 1403 例 CRC 中确定了所有证实的 LS 病例。反射 BRAFV600E 和 MMR IHC 是简单廉价的检测方法，可促进 LS 的普遍筛查，并确定 BRAFV600E 突变 MSS CRC 表型的不良预后。
