SAN FRANCISCO—Patients with stage IV gastric tumors positive for mesenchymal epithelial transition factor (MET) protein expression have poorer survival than those without MET expression, results of a Danish cohort study reported at the 2014 Gastrointestinal Cancers Symposium.
The 1-year survival rate was 18% in patients with MET-positive tumors compared with 39% for those with MET-negative tumors (mortality rate ratio, 2.3; 95% CI: 1.4-3.9).
Although recent clinical trial data indicate patients with late-stage gastric cancer and positive MET protein expression do poorly, there is a dearth of information “about the real-world prevalence of MET-positive cancers and the associated prognosis,” said Rune Erichsen, MD, PhD, of Regionshospitalet Randers, Randers, Denmark, and colleagues.
The investigators used medical registries from a single institution in northern Denmark to identify patients with stage IV gastric cancer from 2003 to 2010. They analyzed MET protein expression in archived paraffin-embedded cancer specimens by immunohistochemistry and defined MET-positivity as 25% or more of tumor cells with membrane staining.
Of the 101 patients included in the study, 56 (55%) had MET-positive tumors, with analysis based on biopsy from the primary lesion (77%), surgical resection (9%), and biopsy from metastasis (8%). Of the 45 patients with MET-negative tumors, this was 82%, 9%, and 9%, respectively.
Those with MET-positive tumors were younger at diagnosis (median age, 65 vs. 68 years), included more men (79% vs. 69%), and had higher comorbidity levels, with a Charlson Comorbidity Index of 0, 1-2, and 3+ of 77%, 13%, and 6% compared with 67%, 27%, and 7% in those with MET-negative tumors.
On histology, 48% of those with MET-positive tumors had poorly differentiated cancers versus 38% with MET-negative tumors. Signet cancer was 16% versus 12%; tubular cancer, 23% versus 16%; and neuroendocrine cancer, 1% versus 0%, respectively.
Patients with MET-positive tumors were less likely to undergo surgery (50% vs. 60%) or chemotherapy (52% vs. 62%) than those with MET-negative tumors, and more likely to undergo radiation (16% vs. 11%).
The 2014 Gastrointestinal Cancers Symposium is sponsored by the American Gastroenterological Association (AGA) Institute, the American Society of Clinical Oncology (ASCO), the American Society for Radiation Oncology (ASTRO), and the Society of Surgical Oncology (SSO).