BRAF and KRAS mutations in penile cancer and their correlation with clinical features.
221 Background: Penile cancer is a rare disease in developed countries. While surgery may be curative for patients with localized disease, for metastatic patients systemic chemotherapy may offer palliation with usually short-lived responses. Thus, new options in this setting are needed. Retrospective series have reported EGFR overexpression in more than 90% of the cases and also interesting results of EGFR directed therapies in these patients have been comunicated. The role of KRAS status or other molecular markers as prognostic or predictive factors remains unclear. The aim of this study was to determine the prevalence of BRAF and KRAS somatic mutations in penile cancer and their correlation with clinicopathologic features. Methods: We analyzed 28 samples collected from de archives of the Pathology Department at our institution from 1996 to 2009. The DNAs were extracted from FFPE blocks by Biorobot EZ1 following the manufacturer protocol of the EZ1-DNA Tissue kit (Qiagen). KRAS and BRAF mutations were amplified with specific primers, and sequenced by Sanger with Bigdye terminator v3.1 Cycle Sequencing Kit. Medical records were reviewed for clinical data. Results: No BRAF mutations were found, but we identified somatic missense mutations in the KRAS gene (all activating G12D mutations) in 6/27 samples (22%, one not evaluable). Median age at diagnosis (73 vs. 71), grade and histologic subtype did not differ between wt and mutated (mt) patients. There was a trend toward a more advanced stage at diagnosis in mt versus wt : 33 versus 47% stage I, 16 versus 9% stage II and 50 versus 38% stage III respectively. 2/6 mt patients died (due to other causes) as did 5/21 wt patients (3 of them because of disease progression). Conclusions: BRAF mutations seem not involved in the EGFR pathway in penile carcinomas. The prevalence of KRAS mutations was unexpectedly high in our series and mt patients tended to be diagnosed at a more advanced stage. Unfortunately, no correlation was found with other clinicopathologic features, including overall survival in our small series. These results suggest a role of KRAS mutation in the development of these carcinomas and support the importance to determine KRAS status in patients to be treated with anti-EGFR based therapies. No significant financial relationships to disclose.