Vulvar Squamous Cell Carcinoma is a Multifactorial Disease Following Two Separate and Independent Pathways
Two separate pathways leading to vulvar carcinoma have been suggested. First, a human papillomavirus (HPV)-dependent pathway, in which premalignant stages of vulvar cancer are the classic vulvar intraepithelial neoplasia (VIN) lesions. Second, an HPV-independent pathway, associated with differentiated VIN III lesions and/or lichen sclerosus. To obtain insight into the mechanisms underlying these pathways, we determined the relationship between HPV DNA and the expression of p14(ARF) and p16(INK4A) in non- and (pre)malignant vulvar lesions. Seventy-three archival samples of non- and (pre)neoplastic vulvar lesions were selected and tested for hr-HPV DNA using a broad-spectrum HPV detection/genotyping assay (SPF(10)-LiPA) and the expression of p14(ARF) and p16(INK4A). The prevalence of HPV increased with the severity of the classic VIN lesions; in VIN I no hr-HPV was detected, in VIN II 43%, and in VIN III 71% of the samples were hr-HPV-positive. Roughly the same was true for the expression of p14(ARF) and p16(INK4A). The simultaneous expression of p14(ARF) and p16(INK4A) was highly associated with the presence of hr-HPV DNA. Hr-HPV was detected in only a single case of the differentiated VIN III lesions, whereas no expression of p14(ARF) was found and 16(INK4A) was present in only two cases. All 16 samples of vulvar cancer were hr-HPV DNA- negative, although in respectively 63% and 25%, p14(ARF) and p16(INK4A) was expressed. No relation was found between hr-HPV and the expression of p14(ARF) and p16(INK4A) in the 20 nonneoplastic vulvar lesions. Our results provide further evidence that vulvar squamous cell carcinoma is a multifactorial disease that develops from two different pathways. First, an HPV-dependent pathway with a remarkable resemblance to CIN lesions and cervical carcinoma and second, an HPV-independent pathway in which differentiated VIN III lesions that are hr-HPV-negative may be precursors.
Available from: Linda S Nooij
- "dVIN can be difficult to diagnose for both clinicians and pathologists because of its subtle clinical and histological appearance . HPV-independent VSCC is associated with a worse prognosis than HPV-associated VSCC  . However, its carcinogenesis has not been fully clarified. "
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ABSTRACT: Vulvar cancer is a relatively rare gynecologic malignancy with an annual incidence in developed countries of approximately 2 per 100,000 women. Vulvar squamous cell carcinoma (VSCC) has two etiological pathways: a high risk human papillomavirus (HPV)-dependent route, which has usual vulvar intraepithelial neoplasia (uVIN) as a precursor lesion, and an HPV-independent route, which is associated with differentiated VIN (dVIN), lichen sclerosus, and genetic alterations, such as TP53 mutations. Research on the molecular etiology of vulvar cancer has increased in the past years, not only regarding genetic alterations, but also epigenetic changes. In genetic alterations, a mutation irreversibly changes the nucleotide sequence of the DNA, or the number of copies of chromosomes per cell is altered. In epigenetics, the nucleotide sequence remains the same but genes can be 'switched' on or off by, for example, DNA methylation or histone modification. We searched the current literature on genetic and epigenetic alterations in VSCC and its precursor lesions. Many studies have reported a higher incidence of somatic mutations in HPV-negative tumors compared to HPV-positive tumors, with TP53 mutations being the most frequent. Allelic imbalances or loss of heterozygosity are more frequently found in higher stages of dysplasia and in invasive carcinomas, but it is not exclusive to HPV-negative tumors. A limited number of studies are available on epigenetic changes in vulvar lesions, with hypermethylation of CDKN2A being the most frequently investigated change. For most genes, hypermethylation occurs more frequently in vulvar squamous cell carcinomas than in precursor lesions. As most studies have focused on HPV infection and TP53 mutations, we suggest that more research should be performed using whole genome or next generation sequencing to determine the true landscape of genetic and epigenetic alterations in vulvar squamous cell carcinoma.
Available from: Marjolijn (Jolijn) D Trietsch
- "The second type is typically seen in elderly patients and seems to develop independently from HPV infection. The HPV-independent type of carcinoma is associated with lichen sclerosis and mutations in the TP53 gene, but its etiology is much less well understood than the HPV-positive type  . "
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Two etiologic pathways of vulvar cancer are known, a human papillomavirus (HPV)- and a TP53-associated route, respectively, but other genetic changes may also play a role. Studies on somatic mutations in vulvar cancer other than TP53 are limited in number and size. In this study, we investigated the prevalence of genetic mutations in 107 vulvar squamous cell carcinomas (VSCCs).
A total of 107 paraffin-embedded tissue samples of primarily surgically treated VSCCs were tested for HPV infection and screened for mutations in 14 genes (BRAF, CDKN2A(p16), CTNNB1, FBXW7, FGFR2, FGFR3, FOXL2, HRAS, KRAS, NRAS, PIK3CA, PPP2R1A, PTEN, and TP53) using Sanger sequencing and mass spectrometry.
Mutations were detected in 7 genes. Of 107 VSCCs, 66 tumors (62%) contained at least one mutation (TP53 = 58, CDKN2A(p16) = 14, HRAS = 10, PIK3CA = 7, PPP2R1A = 3, KRAS = 1, PTEN = 1). Mutations occurred most frequently in HPV-negative samples. Five-year survival was significantly worse for patients with a mutation (47% vs 59%, P = .035), with a large effect from patients carrying HRAS-mutations.
Somatic mutations were detected in 62% of VSCCs. As expected, HPV infection and TP53-mutations play a key role in the development of VSCC, but CDKN2A(p16), HRAS, and PIK3CA-mutations were also frequently seen in HPV-negative patients. Patients with somatic mutations, especially HRAS-mutations, have a significantly worse prognosis than patients lacking these changes, which could be of importance for the development of targeted therapy.
Available from: Stéphanie Demoulin
- "After viral DNA integration in human host-cells, these viral oncoproteins E6 and E7 are overexpressed. Then, E6 degrades the tumor suppressor protein p53, therefore inducing the absence of cell cycle arrest . Moreover, E7 induces an inactive retinoblastoma tumor suppressor gene product, resulting in hyperproliferation of host cells, with overexpression of the cell cycle-related marker p16 . "
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ABSTRACT: Condyloma acuminatum, intraepithelial neoplasia, and squamous cell carcinoma are three relatively frequent vulvar lesions. Condyloma acuminatum is induced by low risk genotypes of human papillomavirus (HPV). Vulvar intraepithelial neoplasia (VIN) and squamous cell carcinoma have different etiopathogenic pathways and are related or not with high risk HPV types. The goal of this paper is to review the main pathological and clinical features of these lesions. A special attention has been paid also to epidemiological data, pathological classification, and clinical implications of these diseases.
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