K-ras Mutations in Triple Negative Breast Carcinomas
Ibrahim Kulac, Serdar Balci, Kadri Altundag, Atac Baykal, Gaye Guler Tezel, Gulnur Guler. Hacettepe University Faculty of Medicine, Ankara, Turkey; Yildirim Beyazit University Ankara Ataturk Research and Education Hospital, Ankara, Turkey
Background: K-ras mutations are seen in 40% of colorectal cancers (CRC). Only CRCs with wild type K-ras respond to anti-EGFR treatments. Triple negative breast (TN) tumors show high incidence (around 60%) of EGFR expression and they are also good candidates for anti-EGFR treatments. One previous report showed no K-ras codon 12 and 13 mutations in TN tumors. So we aimed to search for K-ras mutations in our cohort.
Design: 47 primary breast carcinomas which are negative for ER, PR and HER2 are included. DNA was extracted from sections that constitute more than 75% invasive tumor tissue. K-ras mutations in codon12, 13 and 61 were analyzed by pyrosequencing on the Qiagen PyroMark Q24. Only the mutation levels which were 3% more than the level of detection defined in the product manual were accepted as positive.
Results: Mean age of patients were 51.9±14.0 (min:25, max:85). Of the 47 TN tumors 41 (87.2%) were grade 3, 6 (12.8%) were grade 2 tumors.
2 (4.3%) cases had mutation in codon 12; 2 (4.3%) cases in codon 13; 8 (17.0%) cases in codon 61. Ten (21.3%) cases had mutation at least in one codon. One (2.1%) case had mutation in codon 12&61 and one other in codon 13&61 simultaneously. None of the cases had mutation in all three codons.
Mutations were GGT>GTT and GGT>GAT in codon 12; GGC>GAC in codon 13 and TTG>GTG in codon 61.
Conclusions: We found that K-ras mutations can be seen in TN tumors. In clinical trials with EGFR targeted agents, K-ras mutation detection may be beneficial to predict unresponsive patients.
Wednesday, March 21, 2012 1:00 PM
Poster Session VI # 15, Wednesday Afternoon