The feasibility of choosing intensity-modulated radiotherapy to treat 3 -5 brain metastases from non-small cell lung cancer

Objective: This study evaluates the feasibility of intensity-modulated radiation therapy (IMRT) to treat patients with 1 -5 brain metastases from non-small cell lung cancer (NSCLC). Methods: 30 IMRT patients with brain metastases for NSCLC studied retrospectively. Whole brain radiotherapy plus three-dimensional conformal radiotherapy (WBRT + 3DCRT) and WBRT plus stereotactic radiotherapy (WBRT + SRT) plans were generated. Planning target volume (PTV) and organs at risk dose were measured and compared by dose volume histogram. Differences were analyzed in the three techniques by Wilcoxon Z -test. Results: D99% of the shoulder (D99%-D90%) from IMRT were higher than from WBRT + 3DCRT and WBRT + SRT in all cases. From D15% of slope (D90%-D10%) to D5% of tail (D10% -D1%), IMRT were lower than WBRT + 3DCRT and WBRT + SRT (Z =- 4.72, P =0.000 and Z =- 4.72, P =0.000). D10% and D5% of IMRT were (35.1 ±1.42) Gy and (37.7 ±2.91) Gy, WBRT + 3DCRT were (36.5±2.86) Gy and ( 39.1 ± 3.56) Gy; WBRT + SRT were (36.2 ± 2.57) Gy and ( 38.7 ± 3.67) Gy. IMRT vs WBRT + 3DCRT and WBRT + SRT were significant (Z=-3.18, -3.18, P=0.001, 0.001 and Z=- 4.11, - 3.02, P =0.000, 0.002) in 13 patients with 3 - 5 brain metastases. The total mean monitor units were 14756.3, 9614.8 and 9043.2 for IMRT, WBRT + 3DCRT and WBRT + SRT plans, respectively, with a 38.7% reduction from IMRT to WBRT + SRT (Z =-4.78, -4.78, P =0.000, 0.000). The brain doses around metastases were similar in the three techniques with 1 -2 metastases, but IMRT was the best with 3 -5 metastases. Conclusions: IMRT can advance brain metastases dose and improve the planning target minimum dose and spare the dose around brain metastases. Only IMRT is the best choice for just sparing the dose around brain metastases among 3 -5 brain metastases. (authors)