In HER2+ GC patients with primary resistance, increased signet ring cell (SRC) histology (21.9% vs. 6.2%, p = 0.031) and a higher frequency of initial bone metastasis (25.0% vs. 7.2%, p < 0.025) was observed along with poor performance status (ECOG ≥2: 18.7% vs. 9.2%, p = 0.001). Here, ERBB2 is linked to bone metastasis.