Non-small-cell lung cancer: dose escalation by target splitting with asymmetric collimation

In order to increase conformation, the target volume is split into a cranial and a caudal part. Both volumes are planned and treated completely independent, using half-collimated fields to prevent over- or under-dosages in the junction plane. In comparison with conventional techniques, the irradiated volume of normal ipsilateral lung tissues at dose levels >or= 65 Gy, >or= 45 Gy, and >or= 20 Gy can be lowered to values of 37%, 49%, and 86%, respectively; other organs at risk, such as the heart and esophagus, can also be significantly spared. From December 1995 to December 1999, 54 non-small-cell lung cancer patients were treated with doses > 80 Gy (mean, 86.3 Gy; range 80.1-94.9 Gy, International Commission on Radiation Units and Measurements). Twenty-two patients were stage I or stage II, and 32 patients were stage III. Fifteen of the 32 stage III patients received chemotherapy before radiotherapy. Only 1 patient showed a transient grade 3 toxicity (pneumonitis), and at the time of this review, no grade 4/5 toxicity has been observed.