The Effect Of Different Dose And Sites Of Irradiation On Immune Cell Subsets In Peripheral Blood Of Patients With Lung Cancer

BackgroundLung cancer is one of the most common causes of cancer-related deaths in the world.At present,the treatments for lung cancer include surgery,chemotherapy,targeted treatment,radiotherapy,immunotherapy and so on.Brain metastasis is one of the most common metastasis sites in lung cancer patients who underwent disease progression after receiving systematic treatment,and lung cancer brain metastasis patients have a survival time of only 2-3 months without the intervention of treatment.At present,multidisciplinary treatments of lung cancer brain metastasis are hotly debated,especially the exploration of the best combination of radiation therapy and immunotherapy therapy.ObjectivesTo explore the effect of different irradiation doses,sites as well as the planning target volume(PTV)on systemic immunity in patients with lung cancer by detecting the changes in the percentage of lymphocyte subsets in peripheral blood before and after radiotherapy.Materials and MethodsPeripheral blood in 48 patients with lung cancer receiving radiotherapy were collected(before,during and after radiation),and the lymphocyte subsets as follow were examined:total T cell(CD3+),CD4+T cell,CD8+T cell,CD3+CD4+/CD3+CD8+,natural killer cell,memory T-helper cell subpopulation(CD4+ CD45RO+),CD4+naive T-cell subset(CD4+CD45RA+),interleukin-2(IL-2)receptor a(CD25+),B cells(CD3-CD19+),regulatory T cells(CD4+CD25+).At the same time,the difference between various corresponding planning target volume(PTV)(100%,80%,60%,40%,20%of the total radiation dose)of irradiated sites(thoracic primary lesions,brain metastasis)and the percentage of immune cell subsets in peripheral blood was analyzed using spearman correlation analysis.ResultsAmong non-small cell lung cancer(NSCLC)patients treated with thoracic radiation(n=21),B cells in patients receiving 20Gy/10F(P=0.0046)irradiation were significantly lower than that before radiotherapy.However,CD4+naive T-cells decreased significantly at each dose point compared with that before radiotherapy,P values were 0.0304,<0.0001 and<0.0004,respectively.However,the CD4+CD45RA+subset decreased evidently after completing radiation compared with that after 10 fractions of irradiation(P=0.0390).For small cell lung cancer(SCLC)patients who underwent thoracic radiotherapy,the percentage of CD4+ naive T-cells subgroup at the end of chest radiation declined significantly when compared to that of 10 fractions of radiotherapy was delivered.And the P-value was 0.0444.Patients with NSCLC(n=14)who received brain radiation(regimen:40Gy/20F for whole brain,54-56Gy/20F for multiple brain metastases)had a significantly reduced B lymphocyte subsets after finishing irradiation(20F)compared with those at the beginning of radiotherapy(P=0.039).The changes of other subsets were not statistically significant.In addition,the results showed that the difference between CD4+CD45RA+T cell subgroups and B lymphocyte subsets(CD3-CD19+)at different detection time was generally negatively related to the various volume of PTV at different irradiated sites,while the percentage of memory T-cell sub-groups(CD4+CD45RO+),and total T-cells(CD3+).was positively related to the volume of PTV at different irradiated sites in general.ConclusionThe effects of different radiotherapy doses and different sites on different subgroups of immune cells were not identical.It is necessary to expand the sample size to further optimize the combination of radiotherapy and immunotherapy.