Nasopharyngeal carcinoma.: Treatment planning with IMRT and 3D conformal radiotherapy

The study was undertaken in order to compare dose plans for intensity-modulated radiotherapy (IMRT) with 3D conformal radiotherapy (3D-CRT) dose plans in patients with nasopharyngeal carcinoma (NPC). Clinical data from 20 consecutive patients treated with IMRT are presented. For 11 patients 3D-CRT plans were made and compared to the IMRT plans with respect to doses to the planning target volumes (PTVs) and to organs at risk (OARs). For comparison of the conformation of dose to defined target volumes the conformity index (CI) was used. Target volume coverage and critical organ protection were significantly improved with IMRT compared to 3D-CRT. One-year loco-regional control, distant metastasis-free survival, and overall survival were 79%, 72%, and 80%. Two patients have had recurrence in the clinical target volume (CTV) only and seven patients have relapsed in distant organs and/or in head-and-neck areas outside the target areas. The study confirms that IMRT is superior to 3D-CRT in the treatment of NPC. As locoregional control of NPC improves we are facing an increasing number of recurrences outside the irradiated area.