Lymphocyte depletion after neoadjuvant chemoradiotherapy for operable gastric cancer. (TUM10P.1039)

Abstract

Abstract The purpose of this study was to assess the effect of preoperative chemoradiotherapy (CRT) for operable gastric cancer on lymphocyte subpopulations counts. A total of 35 patients with adenocarcinoma of the stomach were investigated. The preoperative CRT regime consisted of radiotherapy and chemotherapy. The total dose of 45 Gy was administered in 25 fractions, with 5 fractions per week for 5 weeks. Analysis of lymphocyte subpopulations in peripheral blood was carried out before and during treatment (5 analyses for each patients) using a BD Multitest IMK Kit (Becton Dickinson). The data were analyzed with ANOVA. Before and after CRT, the mean values (MVs) of the subtype counts (SD) were as follow: lymphocytes, 1,788 cells/µl (±694) and 239 cells/µl (±131); CD3+CD4+ cells, 738 cells/µl (353) and 135 cells/µl (55); CD3+CD8+ cells, 562 cells/µl (±398) and 56 cells/µl (±41); CD3-CD19+ cells, 150 cells/µl (±112) and 2 cells/µl (±2); and CD16+CD56+ cells, 329 cells/µl (±155) and 28 cells/µl (±36). Every week, we have observed the gradual depletion of all subset of lymphocytes and those differences were statistically significant (p<0.0000). Before CRT, the MV of the CD4+/CD8+ ratio was 1.58 (SD±0.97 ). This ratio has gradually increased during CRT. At the end of treatment, the MV of the CD4+/CD8+ ratio was 2,96 (SD±2,04), p<0.0000. Preoperative chemoradiotherapy induces depletion of all lymphocyte subpopulations.