KRAS and BRAF mutations in sinonasal cancer

Abstract

[corrected] Despite improvements in the field of surgery and radiotherapy, the overall prognosis of sinonasal carcinomas is poor, mainly due to the difficulty to resect the tumour completely in this anatomically complex region. Therefore, there is great need for alternative treatments. Knowledge of the KRAS and BRAF mutational status would become clinically important with regard to the possible use of anti-EGFR therapies. DNA was extracted from paraffin embedded tumour samples from 57 cases of sinonasal squamous cell carcinoma (SNSCC) and from fresh frozen tumour samples from 58 cases of intestinal-type sinonasal adenocarcinoma (ITAC). Point mutations were analysed for KRAS exon 2 (codons 12 and 13) and BRAF (exon 15, V600E) by direct sequencing. Neither KRAS nor BRAF showed any mutations in the SNSCC, whereas 7/58 (12%) ITAC harboured KRAS mutations and no BRAF mutations. All seven cases with KRAS mutation concerned well-differentiated and less aggressive (papillary and colonic type) ITAC, all patients being woodworkers and 4/7 tobacco smokers. Neither of SNSCCs carried mutations in KRAS and BRAF and a low frequency of KRAS mutation was found in ITAC. This suggests that KRAS and BRAF mutations play a limited role in the development of sinonasal cancer and that mutation analysis is not useful as a screening test for sensitivity to anti-EGFR therapy in sinonasal cancer.