Finally, we attempted to find out in a multivariate analysis, which of the following primary tumour factors (1) subcategories of BC (luminal A, luminal B/HER2-, luminal B/HER2+, TNBC and HER2 overexpressing), (2) histological subtypes, (3) age at primary diagnosis, (4) tumour size, (5) number of affected lymph nodes, (6) grading and (7) NPI are associated with bone-only-specific distant recurrence in BC. This evidence concerns the gene ERBB2 and neoplasm.