Human epidermal growth factor receptor-2 gene amplification in gastric cancer using tissue microarray technology

AIM:To assess human epidermal growth factor receptor-2 (HER2)-status in gastric cancer and matched lymph node metastases by immunohistochemistry (IHC) and chromogenic in situ hybridization (CISH).METHODS:120 cases of primary gastric carcinomas and 45 matched lymph node metastases from patients with full clinicopathological features were mounted onto multiple-punch and single-punch tissue microarrays,respectively,and examined for HER2 overexpression and gene amplification by IHC and CISH.RESULTS:Twenty-four tumors (20%) expressed HER2 immunohistochemically.An IHC score of ≥ 2+ was observed in 20 tumors (16.6%).HER2 amplification was detected by CISH in 19 tumors (15.8%) and in their matched lymph node metastases.A high concordancerate was found between HER2 positivity (as detected by IHC) and HER2 gene amplification (as detected by CISH),since 19 of the 20 IHC positive cases were amplified (95%).All amplified cases had 2+ or 3+ IHC results.Amplification was associated with intestinal phenotype (P < 0.05).No association with grading,staging or survival was found.CONCLUSION:In gastric cancer,HER2 amplification is the main mechanism for HER2 protein overexpression and is preserved in lymph node metastases.

TYMS/KRAS/BRAF molecular profiling predicts survival following adjuvant chemotherapy in colorectal cancer

BACKGROUND Patients with stage II-III colorectal cancer (CRC) treated with adjuvant chemotherapy, gain a 25% survival benefit. In the context of personalized medicine, there is a need to identify patients with CRC who may benefit from adjuvant chemotherapy. Molecular profiling could guide treatment decisions in these patients. Thymidylate synthase (TYMS) gene polymorphisms, KRAS and BRAF could be included in the molecular profile under consideration. AIM To investigate the association of TYMS gene polymorphisms, KRAS and BRAF mutations with survival of CRC patients treated with chemotherapy.METHODS A retrospective study studied formalin-fixed paraffin-embedded tissues (FFPEs) of consecutive patients treated with adjuvant chemotherapy during January/2005-January/2007. FFPEs were analysed with PCR for the detection of TYMS polymorphisms, mutated KRAS (mKRAS) and BRAF (mBRAF). Patients were classified into three groups (high, medium and low risk) according to 5’UTR TYMS polymorphisms Similarly, based on 3’UTR polymorphism ins/loss of heterozygosity (LOH) patients were allocated into two groups (high and low risk of relapse, respectively). Cox regression models examined the associated 5- year survival outcomes. RESULTS One hundred and thirty patients with early stage CRC (stage I-II: 55 patients;stage III 75 patients;colon: 70 patients;rectal: 60 patients) were treated with surgery and chemotherapy. The 5-year disease free survival and overall survival rate was 61.6% and 73.9% respectively. 5’UTR polymorphisms of intermediate TYMS polymorphisms (2RG/3RG, 2RG/LOH, 3RC/LOH) were associated with lower risk for relapse [hazard ratio (HR) 0.320, P = 0.02 and HR 0.343, P = 0.013 respectively] and death (HR 0.368, P = 0.031 and HR 0.394, P = 0.029 respectively). The 3’UTR polymorphism ins/LOH was independently associated with increased risk for disease recurrence (P = 0.001) and death (P = 0.005). mBRAF (3.8% of patients) was associated with increased risk of death (HR 4.500, P = 0.022) whereas mKRAS (39% of patients) not. CONCLUSION Prospective validating studies are required to confirm whether 2RG/3RG, 2RG/LOH, 3RC/LOH, absence of ins/LOH and wild type BRAF may indicate patients at lower risk of relapse following adjuvant chemotherapy.