Xing Deyin, Fadare Oluwole
Departments of Pathology, Oncology, Gynecology and Obstetrics, The Johns Hopkins Medical Institutions, Baltimore, MD, United States.
Department of Pathology, University of California San Diego Health, La Jolla, CA, United States.
Semin Diagn Pathol. 2021 Jan;38(1):50-61. doi: 10.1053/j.semdp.2020.09.010. Epub 2020 Sep 25.
Vulvar squamous cell carcinomas (VSCC), which constitute over 90% of vulvar malignancies in adults, are classifiable into 2 subgroups that are mostly clinicopathologically distinct, a classification that is fundamentally based whether or not the tumors are HPV-mediated. In this review, we aim to summarize the recent advances in the understanding of molecular events in the pathogenesis of VSCC, including common and targetable mutations, copy number alterations, epigenetics, noncoding RNAs, and tumor immune microenvironment, which may provide insight into the future management of the disease. These events show substantial differences between the 2 subgroups, although significant areas of overlap exist. Recurrent, driver mutations appear to be substantially more prevalent in HPV(-) VSCC. TP53 mutations are the most common somatic mutations in VSCC overall, and are notably predominant in the HPV(-) VSCC, where 30-88% show a mutation. TP53 mutations are associated with worse patient outcomes, and co-mutations between TP53 and either HRAS, PIK3CA or CDKN2A appear to define subsets with even worse outcomes. A wide variety of other somatic mutations have been identified, including a subset with different mutational frequencies between HPV(+) and HPV(-) VSCC. CDKN2A mutations are common, and have been identified in 21 to 55% of HPV(-) VSCC, and in 2 to 25% of HPV(+) VSCC. Hypermethylation of CDKN2A is the most frequently reported epigenetic alteration in VSCC and the expression of some microRNAs may be associated with patient outcomes. The PTEN/PI3K/AKT/mTOR pathway is commonly altered in HPV(+) VSCC, and is accordingly potentially targetable. HPV-positivity/p16 block expression by immunohistochemistry has been found to be an independent prognostic marker for improved survival in VSCC, and may have some predictive value in VSCC patients treated with definitive radiotherapy. 22-39.3% and 68% of VSCC show EGFR amplification and protein overexpression respectively, although the prognostic and predictive value of an EGFR alteration requires additional study. Recurrent chromosomal gains in VSCCs have been found at 1q, 2q, 3q, 4p, 5p, 7p, 8p, 8q, and 12q, and there may be differential patterns of alterations depending on HPV-status. At least one-third of VSCC patients may potentially benefit from immune checkpoint inhibition therapy, based on a high frequency of PD-L1 expression or amplification, or a high tumor mutational burden. Additional studies are ultimately required to better understand the global landscape of genetic and epigenetic alterations in VSCC, and to identify and test potential targets for clinical application.
外阴鳞状细胞癌(VSCC)占成人外阴恶性肿瘤的90%以上,可分为两个临床病理特征大多不同的亚组,这种分类基本基于肿瘤是否由人乳头瘤病毒(HPV)介导。在本综述中,我们旨在总结近年来在理解VSCC发病机制中分子事件方面的进展,包括常见和可靶向的突变、拷贝数改变、表观遗传学、非编码RNA和肿瘤免疫微环境,这可能为该疾病的未来治疗提供思路。尽管存在显著的重叠区域,但这些事件在两个亚组之间显示出实质性差异。复发性驱动突变似乎在HPV(-)VSCC中更为普遍。TP53突变是VSCC总体上最常见的体细胞突变,在HPV(-)VSCC中尤为突出,其中30-88%显示有突变。TP53突变与患者预后较差相关,TP53与HRAS、PIK3CA或CDKN2A之间的共突变似乎定义了预后更差的亚组。已经鉴定出多种其他体细胞突变,包括HPV(+)和HPV(-)VSCC之间具有不同突变频率的亚组。CDKN2A突变很常见,在21%至55%的HPV(-)VSCC和2%至25%的HPV(+)VSCC中被发现。CDKN2A的高甲基化是VSCC中最常报道的表观遗传改变,一些微小RNA的表达可能与患者预后相关。PTEN/PI3K/AKT/mTOR通路在HPV(+)VSCC中通常发生改变,因此可能是可靶向的。通过免疫组织化学发现HPV阳性/p16阻断表达是VSCC患者生存改善的独立预后标志物,并且可能对接受根治性放疗的VSCC患者具有一定的预测价值。分别有22%-39.3%和68%的VSCC显示表皮生长因子受体(EGFR)扩增和蛋白过表达,尽管EGFR改变的预后和预测价值需要进一步研究。在VSCC中已发现1q、2q、3q、4p、5p、7p、8p、8q和12q存在复发性染色体增加,并且根据HPV状态可能存在不同的改变模式。基于程序性死亡受体配体1(PD-L1)表达或扩增的高频率或高肿瘤突变负荷,至少三分之一的VSCC患者可能潜在地受益于免疫检查点抑制治疗。最终需要更多研究来更好地了解VSCC中遗传和表观遗传改变的整体情况,并识别和测试潜在的临床应用靶点。