The results showed that tumor diameter (OR = 2.184 and 95% CI: 1.095–4.356), Ki67 (OR = 1.138 and 95% CI: 1.029–1.259), molecular subtype (OR = 4.370 and 95% CI: 1.486–12.849), number of metastatic sites per patient (OR = 17.633 and 95% CI: 2.884–107.817), and HMGB1 (OR = 1.461 and 95% CI: 1.114–1.917) were independent risk factors for poor prognosis in MBC patients, whereas caspase‐1 (OR = 0.501 and 95% CI: 0.314–0.801) was an independent protective factor against poor prognosis (Table 3). Here, HMGB1 is linked to neoplasm.