ERBB2 and obesity due to melanocortin 4 receptor deficiency: Although most demographic and disease characteristics at inclusion were similar between the linked and non-linked populations, significant differences were observed for primary tumor location (P < 0.0001), G/GEJ adenocarcinoma status (metastatic, P < 0.01), HER2-negativity status (P < 0.01), tumor-node-metastasis (TNM) classification of malignant tumors (primary tumor status, P < 0.0001), and obesity (P = 0.010) (Tables 5 and S3).