Prognostic role of serum soluble ST2 of advanced breast cancer patients: a retrospective cohort study

Background: The soluble suppression of tumorigenicity 2 receptor (sST2) binds to interleukin-33 (IL 33) and blocks IL-33 and ST2 binding, suggesting that sST2 acts as a "decoy" receptor for IL-33 and is involved in the malignant progression of breast cancer. This paper aimed to investigate the differences in sST2 expression in patients with different molecular subtypes of breast cancer and assess its clinical value in the prognostic evaluation of advanced breast cancer. Methods: In this paper, we collected sera from 91 patients firstly diagnosed with advanced breast cancer at the Tianjin Medical University Cancer Institute and Hospital from 2008 to 2021 during their first hospitalization. We detected the expression level of sST2 in the serum of patients with different molecular fractions of breast cancer and analyzed the relationship between serum sST2 levels and breast cancer-related bone metastasis, cardiotoxicity, and overall survival. Bone metastases were detected using the Emission Computed Tomography technique, and chemotherapy drug-induced cardiotoxicity was detected by echocardiography. The Overall Survival was evaluated using the Kaplan-Meier estimator, and multivariate Cox regression analysis was performed to demonstrate the association between variables and sST2 levels. Results: Serum sST2 levels did not vary among the different pathological types, molecular types, and estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor 2 (HER2), and tumor proliferation marker (Ki-67) subgroups, and only differed significantly in the cardiotoxicity group. There were no statistical differences in tissue polypeptide specific antigen (TPSA), carbohydrate antigen 125 (CA125), carcinoembryonic antigen (CEA), carbohydrate antigen 153 (CA153), D-dimer, and inflammatory indexes neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR) among different molecular subgroups. However, except for triple-negative breast cancer (TNBC), there was no difference in peripheral blood soluble ST2 concentrations among other molecular subtypes. Meanwhile, the survival of the high sST2 level group among advanced breast cancer patients was significantly lower than that of the normal group, and sST2 expression was closely related to cardiotoxicity and clinical stage. Conclusions: Serum sST2 is not only traditionally applied to the assessment of cardiac injury, but can also be utilized for assessing the prognosis of advanced breast cancer, excluding the influence of clinical stage and cardiotoxicity.