Role of CD4 and CD8 T-lymphocytes, B-lymphocytes and Natural Killer cells in the prediction of radiation-induced late toxicity in cervical cancer patients.

PURPOSE

To analyse the role of in vitro radio-induced apoptosis of lymphocyte subpopulations as predictive test for late effects in cervical cancer patients treated with radiotherapy.

METHODS AND MATERIALS

Ninety-four consecutive patients and four healthy controls were included in the study. Toxicity was evaluated using the Late Effects Normal Tissue-Subjective, Objective, Management, and Analytic (LENT-SOMA) scale. Peripheral blood lymphocyte subpopulations were isolated and irradiated at 0, 1, 2 and 8 Gy, and then collected 24, 48 and 72 h after irradiation. Apoptosis was measured by flow cytometry.

RESULTS

Radiation-induced apoptosis increased with radiation dose and time of incubation, and data fitted to a semi-logarithmic model defined by two constants: α (percentage of spontaneous cell death) and β (percentage of cell death induced at a determined radiation dose). Higher β values in cytotoxic T-lymphocytes (CD8) and bone cells (B-lymphocytes) were observed in patients with low bowel toxicity (hazard ratio (HR) = 0.96, p = 0.002 for B-cells); low rectal toxicity (HR = 0.96, p = 0.020; HR = 0.93, p = 0.05 for B and CD8 subpopulations respectively); low urinary toxicity (HR = 0.93, p = 0.003 for B-cells) and low sexual toxicity (HR = 0.93, p = 0.010 for CD8-cells).

CONCLUSIONS

Radiation-induced CD8 T-lymphocytes and, for the first time, B-lymphocytes apoptosis can predict differences in late toxicity in cervical cancer patients.