Objective To investigate the effects of radiotherapy on the level of lysophosphatidic acid(LPA)in different patients.

Methods Three groups of patients(metastatic brain tumor group, non-brain tumor group and primary brain tumor group)were given external irradiation(by linear accelerator).LPA level, white blood cell count and platelet count in the blood plasma were evaluated pre-irradiation and after irradiation with 40 Gy and 60 Gy respectively.

Results The LPA level decreased gradually as irradiation doses increase in metastatic brain tumor group non-brain tumor group(after irradiation with 60 Gy < after irradiation with 40 Gy < pre-irradiation).There was significant statistical difference between them(F=21.230, P < 0.001; F=40.884, P < 0.001).In primary brain tumor group, the level of LPA also decreased gradually, but with no significant statistical difference(F=1.980, P > 0.05), and neoplasm volume changed little.White blood cell count and platelet count gradually decreased with the increasing irradiation doses in metastatic brain tumor group and primary brain tumor group, but there was no significant correlation to LPA level.However, there was a negative correlation to LPA level in non-brain tumor group(r=-0.285 and r=-0.237, both P < 0.05).

Conclusions There is a negative correlation between radiotherapy dose and LPA level in metastatic brain tumor patients and non-brain tumor patients.LPA level could be used as a predictor of the effect of the radiotherapy in tumor treatment.