EUROPEAN RADIATION RESEARCH 2012

Frequency of CD34+ Hematopoietic Stem Cells in Peripheral Blood is Prognostic Factor of Larynx Cancer Response to Radiation Therapy

18 Oct 2012, 16:54

1m

Poster Hall (Vietri sul Mare)

poster preferred Modulation of Radiosensitivity Poster Session 3

Speaker

Prof. Irina Zamulaeva (Medical Radiological Research Center of the Ministry of Health of the Russian Federation)

Description

CD34+ hematopoietic stem cells (HSC) are known to migrate from bone marrow into peripheral blood and tumor tissue under the influence of variety of factors produced by the last one. One can suppose that HSC are capable to render considerable influence on cancer progression and efficiency of treatment through inhibition of intratumoral T-lymphocytes, differentiation into dendritic and endothelial cells and participation in formation of pre-metastatic niches. The purpose of the work was to estimate significance of circulating HSC for prognosis of radiosensitivity of larynx cancer in connection with possible participation of these cells in formation of tumor vasculature. Frequency of СD34+CD45low HSC was determined in peripheral blood of 92 cancer patients before treatment and 83 control healthy persons by flow cytometry. The patients were treated with conventional regime of radiotherapy. Regression degree was assessed after the first stage of radiotherapy (30-40 Gy) as an indicator of short-term response to radiotherapy. Frequency of circulating HSC did not significantly differ between total group of cancer patients and age-matched healthy persons. However patients with regional lymph nodes involvement demonstrated increase of HSC frequency, especially expressed at early stages (Т1+Т2) of disease: mean frequencies (±SE) of HSC in N+ and N0 patients were (18.8±5.8)x10^-4 and (8.2±1.2)x 10^-4, accordingly (р=0.02). There was not found significant association between quantity of circulating HSC and such conventional prognostic factors as primary tumor extent (stage T) or histological type. At the same time pretreatment frequency of these cells was associated with short-term clinical outcome: high degree of cancer regression (> 50 %) was observed in 74% of patients with relatively high frequency of circulating HSC (>6.0x10^-4) and only in 31% of patients with low frequency of these cells. The difference was highly significant in group of patients with stages Т3+Т4 (р=0.001). The correlation can be explained by known ability HSC to differentiate into endothelial cells or stimulate formation of vessels and thereby to increase vascularization of tumor tissue, oxygenation and, hence, radiosensitivity. Future investigation is necessary to estimate prognostic value of HSC frequency with respect to long-term results of radiotherapy. This work was supported by Ministry of Education and Science of the Russian Federation (grant #14.740.11.0180).