Patients with metastatic breast cancer leading to CD4+ T cell lymphopaenia have poor outcome

Background: Low lymphocyte count is a prognostic factor in cancer patients including metastatic breast cancer patients (MBC) but the relative role of each lymphocyte subtype is unclear in MBC. Methods: The impact of lymphocyte subsets was analysed in two prospective MBC patients' cohorts. Cohort A patients (n = 103) were included before the first line of chemotherapy and cohort B patients (n = 101) were included after at least one line of chemotherapy. Extensive phenotypic analyses were performed on fresh whole blood. Plasma cytokines levels were measured using commercially available Luminex-based multiplex kits. Prognostic value of lymphocyte subsets and circulating cytokines was analysed. Results: In both cohorts, severe lymphopaenia (<0.7 Giga/L) correlated with poor overall survival (OS) (median OS: 6.6 months versus 21.7 months in cohort A and 4.5 versus 9 months in cohort B). CD8(+), CD19(+) and CD56(+) T cell counts had no significant prognostic value for OS. After stratification (60.2, [0.20-0.45], > 0.45 Giga/L), CD4 lymphopaenia appeared to be correlated with poor OS in both cohorts. Furthermore, severe CD4(+) lymphopaenia (60.2 Giga/L) was strongly correlated with poor OS in both cohorts (1.2 months versus 24.9 months in cohort A and 5.7 versus 13.1 months in cohort B). In multivariate analysis, after stratification CD4(+) lymphopaenia appeared to be an independent prognostic factor for OS in both cohorts. CD4(+) lymphopaenia correlated with low plasmatic levels of CCL22 that might directly contribute to CD4(+) lymphopaenia. Conclusions: CD4(+) lymphopaenia was associated with reduced OS in MBC patients regardless of the chemotherapy line. Decreased levels of plasmatic CCL22 may contribute to CD4(+) lymphopaenia. (C) 2012 Elsevier Ltd. All rights reserved.