Changes in peripheral lymphocyte subpopulations following radiation therapy.

Abstract

128 Background: Since ionizing radiation can affect the immune system, in this research we sought to analyze the changes of peripheral blood lymphocyte subpopulations (LS) in patients undergoing Radiation Therapy (RT). Methods: In 2015 we enrolled 58 patients, 97% with no systemic cancer (breast 47%, prostate 23%,head and neck 16%, abdomen-pelvis 11%, metastases 3%). The percentages of patients with lowered LS were determined prior to RT, and at different intervals in the patients’ history.The average dose of RT was 50Gy (+/-10 ) with 2 Gy/day fractions. Results: As baseline, total T lymphocytes, T helper, T suppressor, B lymphocytes and Natural Killer cells, were reduced vs. normal range in 24%, 33%, 24%, 59% and null of patients, respectively.A second blood sample was withdrawn after 14-58 days (mean 36) from starting RT, in which we found significantly increased the patients damaged up to 66%, 65%, 62%, 88% and 7% (p=< 0,0001 for each LS ). Compared with the nadir of LS depletion, at 44 (5-180) and 153 (43-130) days from the completion of RT, all the LS raised significantly, except for a weak value of T Helper category (p=0,0145 and 0,0226 respectively). Conclusions: After common RT regimens for solid tumors, all LS can be substantially impaired, and for the T Helper the recovery is particularly slow in the following months.