Dosimetric Comparison Of IMRT And 3D-CRT In Brain Metastasis Tumors Of NSCLC And IMRT Combined With Concomitant Temozolomide For Brain Metastases From NSCLC

Dosimetric comparison of IMRT and 3D-CRT in brain metastasis tumors of NSCLCObjective:To evaluate the characteristics of three-dimensional conformal radiotherapy(3D-CRT) and intensity modulated radiation therapy(IMRT) of the non- small-cell-lung cancer(NSCLC) brain metastasis tumors, to investigate the dosimetry advantages between IMRT and 3D-CRT. Methods:Nine patients with the brain metastasis tumors of NSCLC accept position fix, CT scan and target delineate,then design the three dimensional conformal radiation therapy(2 fields for the whole brain and 4 fields as a boost treatment for the GTV) and intensity modulated radiation therapy(7 fields for IMRT and 7 fields as a boost treatment for the GTV). Analysis the dose volume histograms(DVH) of two radiotherapy plans and compare two radiotherapy plans with conformal index(CI),homogeneity index(HI),target area dose, target area coverage and endanger organ dose. Results:Compare with the 3D-CRT, IMRT significantly improved the conformal index of both PTV-G and PTV-C(P<0.05),improved the homogeneity index(P<0.05) of PTV-C, increased Dmax and Dmean of PTV-G(P<0.05),had an advantage of Dmean of PTV-C(P<0.05). For the organs at risk, it could’t be improved the irradiation dose of brain stem(P<0.05), but reduced the irradiation dose of eyes, lens, optic nerves, middle ears and parotid glands(P<0.05) in IMRT plan.Conclusions: In short, both IMRT and 3D-CRT can achieve the appropriate target area coverage and meet the requirements of radiation therapy. For the brain metastasis tumors of NSCLC, IMRT plan can guarantee better CI and HI than 3D-CRT plan, improved Dmax and Dmean of PTV-G. Moreover, IMRT plan can significantly reduce the irradiation dose of eyes, lens, optic nerves, middle ears and parotid glands, especially middle ears. It contributes to protect normal tissues of brain. IMRT combined with concomitant temozolomide for brain metastases from non-small-cell lung cancerObjective:To evaluate the short-term efficacy, adverse effects and the impact on Quality of Life(Qo L) of a concomitant treatment with IMRT and Temozolomide(TMZ) in patients with brain metastases from non-small-cell lung cancer(NSCLC). Methods:Seven patients were enrolled and received IMRT for 39 Gy in 13 fractions with concomitant TMZ(75mg/m2/day) orally during RT for three weeks. Results:Two patients achieved complete response(29%), five patients obtained partial response(71%), there were no patients in progression. Therefore, objective responses rate(ORR) reached 100%. The main adverse effects included vomiting, fatigue and dizziness.Grade≥3 of hematologic toxicities did not occur. Conclusion:The benefit of adding temozolomide to IMRT was confirmed in patients with brain metastases from non-small-cell lung cancer(NSCLC).The treatment was active,a significant objective response was observed, and an improvement in quality of life demonstrated by QOL grade(P<0.05).