An isotoxic planning comparison study for stage II-III non-small cell lung cancer: Is intensity-modulated radiotherapy the answer?

Aims: Recent clinical series suggest that treating patients with isotoxic twice-daily radiotherapy may be beneficial. This dosimetric planning study compared the use of intensity-modulated radiotherapy (IMRT) and three-dimensional conformal radiotherapy (3DRT) to deliver isotoxic treatment for non-small cell lung cancer (NSCLC) patients. Materials and methods: Twenty patients with stage II/III NSCLC were selected. A dose-escalated plan was produced retrospectively for each using three different methods: (i) three to five beams 3DRT; (ii) seven beams inverse-planned conformal radiotherapy; (iii) seven beams IMRT. The starting point for dose escalation was 55.8Gy in 1.8Gy per fraction twice-daily. The number of fractions was then increased until one or more organ at risk tolerance dose was exceeded or a maximum dose of 79.2Gy was reached. Results: The median escalated doses were 70.2, 66.6 and 64.8Gy for IMRT, 3DRT and inverse-planned conformal radiotherapy, respectively. IMRT allowed a significant dose increase in comparison with the other two methods (P