EGFR and KRAS Mutation Status in Patients with Non-Small Cell Lung Cancer and Additional Primary Colorectal or Gastric Cancer
Mee Sook Roh, Phil Jo Choi, Choonhee Son. Dong-A University College of Medicine, Busan, Republic of Korea
Background: The molecular analysis of multiple cancers occurring in a single patient may improve understanding of general molecular principles of carcinogenesis. Colorectal cancer (CRC) or gastric cancer (GC) frequently develops as the second primary cancer in Korean non-small cell lung cancer (NSCLC) patients, which might be due in part to a common molecular basis. To determine possible underlying molecular relationships, we analyzed EGFR and KRAS mutation status in patients with NSCLC and additional CRC or GC.
Design: Twenty-eight patients with NSCLC had an occurrence of primary CRC (15 patients) or GC (13 patients) in their history or in the follow-up period. After genomic DNA was extracted from paraffin-embedded tissues, mutation analysis of EGFR gene exons 19 and 21 and KRAS gene codons 12 and 13 were performed using peptide nucleic acid-clamp real-time PCR-based assay in both NSCLCs and their CRCs or GCs.
Results: In 15 NSCLC patients with CRC, the detection rate for EGFR mutation was 40.0% (6 cases: 3 each in exons 19 and 21) of NSCLCs and 13.3% (2 cases: 1 each in exons 19 and 21) of CRCs and that for KRAS mutation was 26.7% (4 cases: all in codon 12) of NSCLCs and 26.7% (4 cases: 3 in codon 12 and 1 in codon 13) of CRCs. Three (20.0%) showed an identical EGFR or KRAS mutation in both NSCLC and CRC: identical EGFR mutation in 2 patients and identical KRAS mutation in 1 patient. In contrast, the detection rate for EGFR mutation was 23.1% (3 cases: 1 in exon 19 and 2 in exon 21) of NSCLCs and 15.4% (2 cases: both in exon 21) of GC in 13 NSCLC patients with GCs. An identical EGFR mutation in both NSCLC and GC was found only 1 patient (7.7%). No KRAS mutation was found in the patients with both NSCLCs and GCs.
|NSCLC/CRC (n=15,%)||NSCLC/GC (n=13,%)|
|EGFR||-/-||9 (60.0)||9 (69.2)|
|-/+||0 (0)||1 (7.7)|
|+/-||4 (26.7)||2 (15.4)|
|+/+||2 (13.3)||1 (7.7)|
|KRAS||-/-||8 (53.3)||13 (100)|
|-/+||3 (20.0)||0 (0)|
|+/-||3 (20.0)||0 (0)|
|+/+||1 (6.7)||0 (0)|