Comparison of proton therapy and conformal X-ray therapy in non-small cell lung cancer (NSCLC).

This study compares the performance of one proton and four conformal X-ray planning techniques in treating non-small cell lung cancer (NSCLC). The treatment volumes for 13 NSCLC patients undergoing radical radiotherapy were planned using the five different techniques and dose-volume histograms (DVH) were used extensively in the comparative analysis. The minimum dose to the phase 2 target volume was escalated to 90 Gy, or until the point at which pre-set tolerance limits of spinal cord or lung were exceeded. The proton plan could treat nine of the 13 patients up to a dose of 90 Gy. Among the four X-ray techniques, performance varied enormously. One of them could not treat any of the patients, even to the conventional 60 Gy level, without failing to meet one or more of the criteria, whilst another one could treat 10 out of the 13 patients, although with this technique only four were permitted to have the dose escalated to 90 Gy. It was also found that two of the 13 patients could not be treated by any of the proton or X-ray plans to the conventional level, and were therefore considered unsuitable for radical radiotherapy. Various issues in conformal NSCLC radiotherapy including organ movement, tumour control, other possible organs at risk etc., are also discussed.