MET deletion is a frequent event in gastric/gastroesophageal junction/esophageal cancer: a cross-sectional analysis of gene status and signal distribution in 1,580 patients.

BACKGROUND

MET gene aberrations are found in several human cancers including gastric, ovarian and lung. In a large multinational cohort of patients with gastric/gastroesophageal junction/esophageal (G/GEJ/E) adenocarcinoma we assessed the MET status with respect to amplification and deletion and correlate the results with the phenotypical gene signal distribution pattern.

METHODS

Tissue specimens from 1,580 patients were analyzed using a novel fluorescence in situ hybridization (FISH) assay employing a MET/CEN-7 IQFISH Probe Mix. MET amplification and deletions were defined as a MET/CEN-7 ratio ≥2.0 and a MET/CEN-7 ratio <0.8, respectively. Furthermore, the link between the MET gene status and the phenotypical signal distribution was investigated.

RESULTS

The prevalence of MET amplification and deletions was found to be 7.2% and 8.7%, respectively. Significant differences were observed with regard to geographic regions and sex. The Asian population had the highest percentage of MET amplification (9.4%) and the lowest percentage of deletions (3.2%). MET deletions was found more frequently among males (10.1%) compared to females (5.3%) and in esophagus (17.6%) compared to the stomach (5.7%). More than 50% of the patients who harbored MET gene amplification had a heterogeneous distribution of the FISH signals. Patients with a focal signal distribution were solely to be found among the MET amplified population. MET deletion were mainly observed in the group of patients with a homogenous signal distribution.

CONCLUSIONS

The screening data from this cross-sectional study showed that MET deletion and amplification are frequent events in G/GEJ/E cancer, which are linked to different phenotypical signal distribution patterns. The role of MET deletion in relation to tumor development is not fully understood but it is likely to play a role in the oncogenic transformation of the cells.