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.