Pulmonary lymphangitis carcinomatosis: A peculiar presentation clustering in MET-amplified gastric cancer.

BACKGROUND: The clinicopathological features of MET-amplified gastric cancer (GC) and real-world data on the efficacy of MET-targeted therapies remain unknown. Pulmonary lymphangitis carcinomatosis (PLC) is a peculiar manifestation of GC, whose management has not been thoroughly described. METHODS: This study analyzed patients diagnosed with MET-amplified GC or GC with PLC at any time point of the disease course from 2011 to 2021 in two centers. Clinicopathological features and survival outcomes of MET-amplified GC were analyzed. The clinical and molecular implications of GC with PLC were discussed. RESULTS: Fifty-eight patients with MET-amplified GC and 20 patients with GC accompanied by PLC were finally enrolled for analysis (including 13 overlapped patients). GC with PLC was more common in female patients (p = 0.010), diagnosed at a younger age (p = 0.002), presented with a higher baseline ECOG PS (p = 0.016), and was more likely to develop lung metastasis (p < 0.001), and serous effusion (p = 0.026) than GC without PLC. Patients with primary MET-amplified GC had a worse prognosis than those with secondary MET-amplified GC (p = 0.005). The application of anti-MET therapy was associated with numerically prolonged survival, but the association was not statistically significant (p = 0.07). MET amplification was concentrated in patients with PLC, in which anti-MET therapies elicited a high response rate. CONCLUSIONS: MET-targeted therapies are efficacious in real-world populations with MET-amplified GC. Patients with PLC have distinct clinical and molecular features and might benefit from MET-targeted therapies.