Background: CXCL10 is a chemokine with chemo attractant properties which signals through G protein-coupled receptor CXCR3. At least two reported isoforms exists; CXCR3-A and CXCR3-B. CXCL10 is involved in the recruitment of leucocytes, immune modulation and angiogenesis. In animal models CXCL10 inhibits tumour growth, metastase formation and inhibits angiogenesis. The receptors have opposite features; CXCR3-A mediates proliferative or anti-apoptotic response and CXCR3-B mediates growth inhibition and apoptosis in response to ligand binding. The aim of this study was to investigate the role of CXCL10 and CXCR3-A as prognostic or tamoxifen treatment predictive factors in breast cancer.
Material and Methods: A randomized tamoxifen trial comprising 1,780 breast cancer patients was conducted in Stockholm, Sweden, 1976–1990. All patients had lymph node negative primary breast cancer and were postmenopausal at the time of diagnosis. The patients were randomized to tamoxifen or no endocrine treatment. We analyzed the protein expression of CXCL10 and the receptor CXCR3A with immunohistochemistry using tissue microarrays, which were constructed from paraffin blocks originating from 912 patients. CXCL10 and CXCR3A could be scored in 793 (87%) and 735 (81%), respectively.
Results: High expression of CXCL10 was associated with significant benefit of tamoxifen treatment concerning local recurrence and breast cancer survival (P=0.02 and P=0.008). For patients with high CXCL10 expression, tamoxifen decreased the risk concerning local recurrence (rate ratio (RR) = 0.56, 95% C.I. 0.33−0.97, P=0.0029) and breast cancer survival (RR 0.6 95% C.I. 0.39−0.97, P=0.023). High expression of CXCR3-A was associated with significant benefit of tamoxifen treatment concerning total recurrence and breast cancer survival (P=0.00001 and P=0.004, respectively). For patients with high CXCR3-A expression, tamoxifen decreased the risk of total recurrence (RR 0.54 95% C.I. 0.35−0.83, P=0.005) and breast cancer survival (RR 0.49 95% C.I. 0.35−0.69, P=0.00003). On the opposite, in the cohort of patients with no endocrine treatment and high CXCR3-A expression, there was an increased risk of total recurrence (P=0.003). (RR 2.07 95% C.I. 1.18−3.61, P=0.011).
Conclusions: This study indicates that high expression of CXCL10 can be used as predictive markers for tamoxifen treatment. Further, high expression of CXCR3-A is related to bad prognosis and predicts tamoxifen treatment in breast cancer patients. This needs to be further evaluated.
Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P1-06-06.