To report acute toxicity, initial outcome results and planning therapeutic parameters in radiation treatment of advanced lung cancer (stage III) with volumetric modulated arcs using RapidArc (RA).

Twenty-four consecutive patients were treated with RA. All showed locally advanced non-small cell lung cancer with stage IIIA-IIIB and with large volumes (GTV:299+/-175cm3, PTV:818+/-206cm3). Dose prescription was 66Gy in 33 fractions to mean PTV. Delivery was performed with two partial arcs with a 6MV photon beam.

From a dosimetric point of view, RA allowed us to respect most planning objectives on target volumes and organs at risk. In particular: for GTV D1%=105.6+/-1.7%, D99%=96.7+/-1.8%, D5%-D95%=6.3+/-1.4%; contra-lateral lung mean dose resulted in 13.7+/-3.9Gy, for spinal cord D1%=39.5+/-4.0Gy, for heart V45Gy=9.0+/-7.0Gy, for esophagus D1%=67.4+/-2.2Gy. Delivery time was 133+/-7s. At three months partial remission >50% was observed in 56% of patients. Acute toxicities at 3 months showed 91% with grade 1 and 9% with grade 2 esophageal toxicity; 18% presented grade 1 and 9% with grade 2 pneumonia; no grade 3 acute toxicity was observed. The short follow-up does not allow assessment of local control and progression free survival.

RA proved to be a safe and advantageous treatment modality for NSCLC with large volumes. Long term observation of patients is needed to assess outcome and late toxicity.

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