Department of Pathology, University of Montreal, Montreal, QC, Canada.
Department of Pathology, The Johns Hopkins Medical Institutions, Baltimore, MD, USA.
Head Neck Pathol. 2021 Dec;15(4):1109-1118. doi: 10.1007/s12105-021-01317-5. Epub 2021 Apr 8.
While P16 immunohistochemistry (IHC) is a well-established surrogate marker of Human Papillomavirus (HPV) in oropharyngeal squamous cell carcinoma (OSCC), Retinoblastoma 1 (RB1) loss may lead to p16 overexpression in the absence of HPV. We determined the proportion of p16-positive/HPV-negative OSCC with RB1 loss and other alterations in RB1/p16 pathway, and tested RB1 IHC as a prognostic biomarker for OSCC, along with the 8th edition of AJCC staging manual. P16 and RB1 IHC and HPV DNA in situ hybridization (ISH) were performed on 257 OSCC. High risk HPV RNA ISH, RB1 fluorescence in situ hybridization (FISH), and next generation sequencing (NGS) were done on p16-positive/HPV DNA ISH-negative OSCC. Disease free survival (DFS) was used as an endpoint. In the entire cohort and in p16-positive (n = 184) and p16-negative (n = 73) subgroups, AJCC 8th edition staging correlated with DFS (p < 0.01). RB1 IHC showed RB1 loss in p16-positive OSCC only (79/184, 43%). RB1 loss by IHC is associated with a better DFS, without providing additional prognostic information for patients with p16-positive OSCC. HPV RNA ISH was positive in 12 of 14 HPV DNA ISH-negative cases. RB1 IHC showed loss in 10 of 15 HPV DNA ISH-negative cases and in 1 of 2 HPV RNA ISH-negative cases. Overall, only one case of p16-positive/HPV RNA ISH-negative OSCC showed RB1 loss by IHC (1/184, 0.5%). Of the 10 p16-positive and HPV DNA ISH-negative cases with RB1 loss by IHC, 2 had RB1 hemizygous deletion and 3 showed Chromosome 13 monosomy by FISH. No RB1 mutations were detected by NGS. Other molecular alterations in p16-positive/HPV DNA ISH-negative cases included TP53 and TERT mutations and DDX3X loss. HPV-independent RB1 inactivation rarely results in false positive p16 IHC. RB1 inactivation by high risk HPV E7 oncoprotein may co-exist with RB1 deletion. RB1 loss is a favorable prognosticator and occurs exclusively in p16-positive OSCC. The 8th edition of the AJCC staging manual satisfactorily predicts DFS of OSCC patients.
虽然 P16 免疫组化（IHC）是口咽鳞状细胞癌（OSCC）中 HPV 的一种成熟的替代标志物，但视网膜母细胞瘤 1（RB1）缺失可能导致 HPV 缺失时 p16 过度表达。我们确定了 RB1 缺失和 p16 通路其他改变的 p16 阳性/HPV 阴性 OSCC 的比例，并测试了 RB1 IHC 作为 OSCC 的预后生物标志物，以及第 8 版 AJCC 分期手册。对 257 例 OSCC 进行了 P16 和 RB1 IHC 和 HPV DNA 原位杂交（ISH）检测。对 p16 阳性/HPV DNA ISH 阴性的 OSCC 进行了高危 HPV RNA ISH、RB1 荧光原位杂交（FISH）和下一代测序（NGS）。无病生存（DFS）用作终点。在整个队列以及 p16 阳性（n=184）和 p16 阴性（n=73）亚组中，第 8 版 AJCC 分期与 DFS 相关（p<0.01）。RB1 IHC 仅在 p16 阳性 OSCC 中显示 RB1 缺失（79/184，43%）。IHC 显示 RB1 缺失与更好的 DFS 相关，但不能为 p16 阳性 OSCC 患者提供额外的预后信息。14 例 HPV DNA ISH 阴性病例中有 12 例 HPV RNA ISH 阳性。RB1 IHC 在 15 例 HPV DNA ISH 阴性病例中的 10 例和 2 例 HPV RNA ISH 阴性病例中的 1 例中显示 RB1 缺失。总体而言，只有 1 例 p16 阳性/HPV RNA ISH 阴性 OSCC 通过 IHC 显示 RB1 缺失（1/184，0.5%）。在 10 例 p16 阳性和 HPV DNA ISH 阴性的病例中，有 2 例 RB1 半合缺失，3 例 FISH 显示 13 号染色体单体缺失。通过 NGS 未检测到 RB1 突变。p16 阳性/HPV DNA ISH 阴性病例中的其他分子改变包括 TP53 和 TERT 突变和 DDX3X 缺失。HPV 非依赖性 RB1 失活很少导致 p16 IHC 假阳性。高危 HPV E7 致癌蛋白引起的 RB1 失活可能与 RB1 缺失并存。RB1 缺失是一个有利的预后指标，仅发生在 p16 阳性的 OSCC 中。第 8 版 AJCC 分期手册令人满意地预测了 OSCC 患者的 DFS。
