| Summary: | <p>Abstract</p> <p>Background</p> <p>With the availability of effective anti-EGFR therapies for various solid malignancies, such as non-cell small lung cancer, colorectal cancer and squamous cell carcinoma of the head and neck, the knowledge of <it>EGFR </it>and <it>K-RAS </it>status becomes clinically important. The aim of this study was to analyse EGFR expression, <it>EGFR </it>gene copy number and <it>EGFR </it>and <it>K-RAS </it>mutations in two cohorts of squamous cell carcinomas, specifically anal canal and tonsil carcinomas.</p> <p>Methods</p> <p>Formalin fixed, paraffin-embedded tissues from anal and tonsil carcinoma were used. EGFR protein expression and <it>EGFR </it>gene copy number were analysed by means of immunohistochemistry and fluorescence in situ hybridisation. The somatic status of the <it>EGFR </it>gene was investigated by PCR using primers specific for exons 18 through 21. For the <it>K-RAS </it>gene, PCR was performed using exon 2 specific primers.</p> <p>Results</p> <p>EGFR immunoreactivity was present in 36/43 (83.7%) of anal canal and in 20/24 (83.3%) of tonsil squamous cell carcinomas. <it>EGFR </it>amplification was absent in anal canal tumours (0/23), but could be identified in 4 of 24 tonsil tumours.</p> <p>From 38 anal canal specimens, 26 specimens were successfully analysed for exon 18, 30 for exon 19, 34 for exon 20 and 30 for exon 21. No <it>EGFR </it>mutations were found in the investigated samples. Thirty samples were sequenced for <it>K-RAS </it>exon 2 and no mutation was identified. From 24 tonsil specimens, 22 were successfully analysed for exon 18 and all 24 specimens for exon 19, 20 and 21. No <it>EGFR </it>mutations were found. Twenty-two samples were sequenced for <it>K-RAS </it>exon 2 and one mutation c.53C > A was identified.</p> <p>Conclusion</p> <p><it>EGFR </it>mutations were absent from squamous cell carcinoma of the anus and tonsils, but EGFR protein expression was detected in the majority of the cases. EGFR amplification was seen in tonsil but not in anal canal carcinomas. In our investigated panel, only one mutation in the <it>K-RAS </it>gene of a tonsil squamous cell carcinoma was identified. This indicates that <it>EGFR </it>and <it>K-RAS </it>mutation analysis is not useful as a screening test for sensitivity to anti-EGFR therapy in anal canal and tonsil squamous cell carcinoma.</p>
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