The Clinical Study Of DVH Parameters Combined With TGF-β1 In Both Serum And Induced Sputum For Predicting Radiation Pneumonitis In Non-small Cell Lung Cancer After Radiotherapy

Objective: To study the relevant factors with radiation pneumonitis (RP) in locally advanced non-small cell lung cancer (NSCLC) after three dimensional conformal radiotherapy (3D-CRT) or intensity modulated radiation therapy (IMRT). To assess the value of TGF-β1 in both serum and induced sputum in predicating the RP, providing a reference for radiotherapy (RT) of NSCLC.Methods: Twenty-three patients with NSCLC treated with 3D-CRT or IMRT in our department between Nov 2007 and Jan 2009 were analyzed and evaluated. Prescription dose for PTV was over 50Gy in all patients, with 1.8-2.0Gy a fraction, 5 days a week. 3D-CRT or IMRT was carried out. The TGF-β1 level in both serum and induced sputum was detected before and near the end of RT for all the patients enrolled. The TGF-β1 level in serum was measured with enzyme-linked immunosorbent assay (ELISA). Immunocytochemistry assay was used to detect TGF-β1 expression in induced sputum sediment. The dosimetric parameters that may be related with RP were recorded according to treating plans, such as the volume, Vdose, Dx, MLD and NTCP of total lung, ipsilateral lung and contralateral lung. Vdose (e.g. V20Gy, V30Gy) is defined as the percent of organ volume receiving greater than a threshold dose (20 or 30Gy, respectively); Dx is defined as the minimum dose to the X% volume of organ that has the highest dose. Radiation pneumonitis was graded according to RTOG radiation scoring criteria every week from the start to three months after the end of treatment. The tumor response was assessed at one month after the end of treatment. The SPSS13.0 software was used in statistics.Results: (1) Tumor response: The complete response rate was 13.04% and the partial response rate was 69.57%. The overall response rate was up to 82.61%. (2)The occurrence of RP: Grade I RP was noted in four patients, grade II RP in three patients, and grade III RP in one patient. No grade IV RP was noted in this cohort. The total incidence of RP was 34.78 % (8/23) and that of Grade II or worse was 17.39 % (4/23). Female and pre-treatment weight loss of more than 5% were risk factors for RP by univariate analysis (P=0.032, 0.006). (3) The relationship between DVH parameters and RP: Univariate analysis revealed that the total lung D90 (TD90) was statistically significant correlated with RP (P=0.047) and the relationship of volume (VTL) and D80 (TD80) of total lung and RP tended to be statistically difference (P=0.097, 0.056). Multivariate analysis revealed that gender, Weight loss, VTL, TD80 and TD₉₀ were not correlated with RP (p>0.05). If the two lungs were regarded as two separate organs, the D₉₀ of contralateral lung (CD₉₀) was the only parameters correlated with RP (P=0.047) and the CD80 tended to be correlated with RP (P=0.053). Multivariate analysis revealed that gender, Weight loss, CD80 and CD90 were not correlated with RP (p>0.05). (4) The relationship between TGF-β1 in serum and RP: The TGF-β1 level in serum pre-RT was 442.20-11280.00pg/ml. The mean value was 1679.36pg/ml and the median was 605.00pg/ml (It was taken as a cut off for TGF-β1 level in this study). The TGF-β1 level in serum post-RT was 280.05-12840.00 pg/ml with a mean value of 2170.63pg/ml and the median of 677.50pg/ml. The absolute TGF-β1 level post-RT was higher than pre-RT, but there was no statistical difference (P=0.139). Patients with higher TGF-β1 level pre-RT had lower RP incidence (20.00%) than those with normal TGF-β1 level pre-RT (54.54%), but there was no statistical difference (P=0.183). Patients with increased level of TGF-β1 had higher incidence of RP (45.45%) than those with decreased TGF-β1 level post-RT (30.00%). Though there was a tendency of higher incidence of RP with the increase of TGF-β1 level, no statistical difference was found (P=0.659). (5) The relationship between TGF-β1 expression in induced sputum and RP: TGF-β1 could be seen positively expressed in induced sputum with immunocytochemistry assay and located in cytoplasm of macrophages or epithelial cells, being brown yellow. Macrophage was the main cells expressing TGF-β1. The higher positive expression rate (68.18%) was found in induced sputum post-RT than pre-RT (27.27%), with statistic al difference (P=0.015). The higher incidence of RP (50.00%) was found in patients with TGF-β1 positively expressed in induced sputum pre-RT than those with TGF-β1 negatively expressed pre-RT (25.00%), without statistical difference (P=0.334). The higher incidence of RP (33.33%) was also found in patients with TGF-β1 positively expressed in induced sputum post-RT than those negatively expressed post-RT (28.57%) (P=1.000). (6) The relationship of TGF-β1 between serum and induced sputum: 39.13% patients with higher TGF-β1 level in serum were found positively expressed in induced sputum. And 55.56% patients with lower TGF-β1 level in serum were found positively expressed in induced sputum, without statistical difference (P=0.355). (7) TGF-β1 level in serum was found elevated in 47.06% patients with tumor response and in 75.00% without (P=0.586). For the patients with elevated TGF-β1 level in serum, the RP developed in 50.00% patients with tumor response and in 33.33% patients without tumor response (P=1.000). (8) DVH parameters combined with TGF-β1 for predicting RP: The RP developed in 60.00% patients with D₉₀>128cGy and elevated TGF-β1 post-RT and was higher than other groups. But there was no statistical difference (P=0.478). The RP was developed in 66.67% patients with D₉₀>128cGy and TGF-β1 positively expressed in induced sputum pre-RT and was higher than other groups, but no statistical difference was found (P=0.739).Conclusion: (1) D90 of total and contralateral lung may become one of predicting parameters for RP. (2) The RP of NSCLC was related with TGF-β1 levels elevated in serum after RT. (3) It is confirmed that TGF-β1 can positively expressed in induced sputum of NSCLC patients, locating in macrophages or epithelial cells. Macrophages are the mainly expressed cells. Patients with TGF-β1 positively expressed in induced sputum have a higher incidence of RP than those with negative expressed. TGF-β1 positive expression in induced sputum is expected to become one of predicting factors for RP. (4) D90 of total lung combined with TGF-β1 expressed in both serum and induced sputum shows an advantage over a single factor in predicting RP.