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Published on: October 5, 2020
Epidermal growth factor receptor and K-RAS status in two cohorts of squamous cell carcinomas
Nancy Van Damme1, Philippe Deron, Nadine Van Roy
1Department of Hepato-Gastroenterology, Digestive Oncology Unit, Ghent University Hospital, De Pintelaan 185 1K12IE, 9000 Ghent, Belgium. nancy.vandamme@ugent.be
Background:
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 EGFR and K-RAS status becomes clinically important. The aim of this study was to analyse EGFR expression, EGFR gene copy number and EGFR and K-RAS mutations in two cohorts of squamous cell carcinomas, specifically anal canal and tonsil carcinomas.
Methods:
Formalin fixed, paraffin-embedded tissues from anal and tonsil carcinoma were used. EGFR protein expression and EGFR gene copy number were analysed by means of immunohistochemistry and fluorescence in situ hybridisation. The somatic status of the EGFR gene was investigated by PCR using primers specific for exons 18 through 21. For the K-RAS gene, PCR was performed using exon 2 specific primers.
Results:
EGFR immunoreactivity was present in 36/43 (83.7%) of anal canal and in 20/24 (83.3%) of tonsil squamous cell carcinomas. EGFR amplification was absent in anal canal tumours (0/23), but could be identified in 4 of 24 tonsil tumours.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 EGFR mutations were found in the investigated samples. Thirty samples were sequenced for K-RAS 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 EGFR mutations were found. Twenty-two samples were sequenced for K-RAS exon 2 and one mutation c.53C > A was identified.
Conclusion:
EGFR 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 K-RAS gene of a tonsil squamous cell carcinoma was identified. This indicates that EGFR and K-RAS mutation analysis is not useful as a screening test for sensitivity to anti-EGFR therapy in anal canal and tonsil squamous cell carcinoma.
Insights
EGFR and K-RAS mutations were absent in most anal and tonsil squamous cell carcinomas, limiting their use as predictive biomarkers for anti-EGFR therapy in these cancers.
Area of Science:
- Oncology
- Molecular Biology
- Genetics
Background:
- Epidermal Growth Factor Receptor (EGFR) and KRAS mutations are crucial for anti-EGFR therapy efficacy in various solid tumors.
- Understanding EGFR and KRAS status is clinically important for targeted cancer treatment.
Purpose of the Study:
- To analyze EGFR expression, gene copy number, and mutations in EGFR and KRAS genes in anal canal and tonsil squamous cell carcinomas.
- To evaluate the potential of EGFR and KRAS mutation analysis as a screening tool for anti-EGFR therapy sensitivity.
Main Methods:
- Immunohistochemistry and fluorescence in situ hybridization were used to assess EGFR protein expression and gene copy number.
- Polymerase Chain Reaction (PCR) was employed to investigate somatic mutations in EGFR (exons 18-21) and KRAS (exon 2).
Main Results:
- EGFR protein expression was high in both anal canal (83.7%) and tonsil (83.3%) squamous cell carcinomas.
- EGFR amplification was observed in tonsil (4/24) but not in anal canal (0/23) tumors.
- No EGFR mutations were detected in either cohort. One KRAS mutation (c.53C > A) was found in a tonsil carcinoma specimen.
Conclusions:
- EGFR mutations are absent in anal canal and tonsil squamous cell carcinomas, despite high EGFR protein expression.
- EGFR amplification is present in tonsil but not anal canal tumors.
- The low frequency of EGFR and KRAS mutations suggests they are not useful screening biomarkers for anti-EGFR therapy in these specific cancer types.
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