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• EGFR expression in vulvar carcinomas: correlation with gene status
  Beatriz M. Maia
  Published on: 18 April 2016

• Published on: 18 April 2016

  EGFR expression in vulvar carcinomas: correlation with gene status

  • Beatriz M. Maia, PhD Student
  • Other Contributors:
    • Andre Mourao Lavorato-Rocha, Iara Sant'Ana Rodrigues, Rafael Malagoli Rocha

  Re: EGFR gene copy number increase in vulvar carcinomas is linked with poor clinical outcome. Woelber et al. J Clin Pathol. 2012 Feb;65(2):133-9.

  Dear editor,

  A very novel issue was assessed by Woelber et al.[1] in their recently published study. This subject has major importance since the medical interest for vulvar carcinoma has increased in the last decade as the recognition of the increasing inci...

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  Re: EGFR gene copy number increase in vulvar carcinomas is linked with poor clinical outcome. Woelber et al. J Clin Pathol. 2012 Feb;65(2):133-9.

  Dear editor,

  A very novel issue was assessed by Woelber et al.[1] in their recently published study. This subject has major importance since the medical interest for vulvar carcinoma has increased in the last decade as the recognition of the increasing incidence of the disease, especially among young women. However, the fact that this carcinoma is an uncommon neoplastic disease makes its relative rarity an obstacle in designing studies to evaluate the effectiveness of the prognostic factors of molecular markers for this type of tumor. Thus, all experience on this type of tumor regarding the molecular aspects, becomes of paramount importance and we would like to share our experience in this field. Woelber et al.[1] studied a series of 183 formalin-fixed paraffin-embedded (FFPE) vulvar squamous cell carcinomas (VSCC) arranged in two TMAs, in which FISH analysis for EGFR, HER-2, CCND1 and MYC, IHQ for EGFR, HER-2 and CCND1, besides HPV detection by conventional PCR were performed. All data were associated to clinicopathological features. As the main results, EGFR copy number increase was found in 39.3% of the tumors and amplification of the EGFR gene in 9%. By IHQ, 53.3% of the samples showed 3+ staining for EGFR, being EGFR protein expression significantly correlated to EGFR copy number increase (p<0.05). Copy number gain of the EGFR locus was associated with high-invasion depth (p=0.045), non- basaloid phenotype (p=0.03), high-tumour stage (p<0.001), human papillomavirus negativity (p=0.04) and the number of lymph node metastases (p=0.02). Therefore, the authors showed that EGFR copy number gains were significantly related to unfavorable patient outcome and suggest the potential role of EGFR as a suitable therapeutic target in a subgroup of vulvar carcinomas. In a very similar fashion, our group studied 139 invasive VSCC arranged in two TMAs in which IHQ and FISH were performed for EGFR. In our approach, IHQ was held on automated Benchmark? Platform (Ventana Medical Systems) using the Zymed 31G7 mouse monoclonal antibody diluted 1:20, being this dilution previously standardized on whole slides of vulvar carcinomas. The absolute intensity of EGFR immunostaining was performed on a fourpoint scale as suggested by several authors [2,3,4] in vulvar carcinomas: (0=negative, 1=weakly positive, 2=positive, 3=strongly positive). In the same way of the study of Woelber and colleagues[1], we used FISH probes ZytoLight SPEC EGFR/CEN 7 Dual Color Probe (ZytoVision?) and the analysis were also performed as Woelber et al[1]. In order to analyze the relationship between the results obtained from IHC and FISH, associations between these data and histopathological features from the classification of the tumors (such as histological type, vascular and perineural invasion among others) and clinical data (such as recurrence, death by cancer and lymph node involvement), obtained from the clinical records of all the 139 patients were performed using the Chi-square test (X2) adopting p<0,05 as significant level. Regarding the amplification of EGFR gene, our results showed a lower rate of amplification (5 out of 78 cases - 6.4%) than those data raised by Woelber et al.[1] - 9%; and Growdon et al. (2008)[4] - 11,7%. Similarly, our IHQ analysis demonstrated only 3.9% of overexpression (3+) among our cases, which is contradictory to previous findings that reported an overexpression of 41-68% for this receptor [1,2,3]. Regarding the correlation between protein expression and amplification, among our cases, all tumors exhibiting amplification demonstrated an intense 3+ immunostaining by IHC, demonstrating a 100%correlation between FISH and IHC. These results corroborate the findings of Growdon et al. (2008) [4] to the observation that all tumors with intense 3+ expression of this receptor exhibited EGFR amplification and contradicts Woelber et al. [1] findings, regarding the occurrence of 20 vulvar carcinomas with EGFR copy number increase (including tumors with high polysomy or amplification) exhibiting low or intermediate levels of EGFR expression (scores 0, 1+ or 2+). Moreover, contrary to Woelber et al[1] study , our results showed no correlation between EGFR expression and the clinical and pathological features evaluated. The only association observed was statistically marginal and was related to FIGO staging, in which the most part of tumors stained negative for EGFR on the membrane (scores 0 and 1+) were classified as FIGO I or II, while the tumors EGFR positive (scores 2+ and 3+) were FIGO III or IV (p=0.08) which, as mentioned by Woelber et al.(2012)[1], may underline the influence of EGFR on tumor progression. Regarding the lack of association between EGFR expression and the clinical and pathological features evaluated, we attribute this result to the great heterogeneity of the intensity of immunostaining for EGFR observed in our cases, also described by Brustmann (2007) [2]. This heterogeneity leads us to believe that TMAs may not be useful for analyzing EGFR amplification in vulvar carcinomas. Anyway, it seems unanimous in the literature and among our results the fact that EGFR is, on greater or lesser extent, amplified in vulvar carcinomas and its overexpression could benefit a small group of patients with the therapy against this tyrosine kinase receptor and that more studies, regarding clinical trials, are required to elucidate this field.

  References: [1] Woelber L, Hess S, Bohlken H et al. EGFR gene copy number increase in vulvar carcinomas is linked with poor clinical outcome. J Clin Pathol. 2012 Feb;65(2):133-9.

  [2] Brustmann, H. Epidermal growth factor receptor is involved in the development of an invasive phenotype in vulvar squamous lesions, but is not related to MIB-1 immunoreactivity. Int J Gynecol Pathol. 2007;26(4):481-89.

  [3] Oonk MH, de Bock GH, van der Veen DJ, Ten Hoor KA, de Hullu JA, Hollema H et al. EGFR expression is associated with groin node metastases in vulvar cancer, but does not improve their prediction. Gynecol Oncol 2007.104(1):109-13.

  [4] Growdon WB, Boisvert SL, Akhavanfard S, Oliva E, Dias-Santagata DC, Kojiro S et al. Decreased survival in EGFR gene amplified vulvar carcinoma. Gynecol Oncol 2008.111(2):289-97.

  Conflict of Interest:

  None declared

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  Conflict of Interest:
  None declared.

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