Image-guided intensity-modulated radiotherapy for pancreatic carcinoma.

PURPOSE: To present the techniques and preliminary outcomes of ultrasound-based image-guided intensity-modulated radiotherapy (IG-IMRT) for pancreatic cancer. MATERIALS AND METHODS: Retrospective analysis of 41 patients treated between November 2000 and March 2005 with IG-IMRT to mean total doses of 55 Gy (range, 45-64 Gy). We analyzed the clinical feasibility of IG-IMRT, dosimetric parameters, and outcomes, including acute gastrointestinal toxicity (RTOG grading). Survival was assessed for adenocarcinoma (n = 35) and other histologies. RESULTS: Mean daily image-guidance corrective shifts were 4.8 +/- 4.3 mm, 7.5 +/- 7.2 mm, and 4.6 +/- 5.9 mm along the x-, y-, and z-axes, respectively (mean 3D correction vector, 11.7 +/- 8.4 mm). Acute upper gastrointestinal toxicity was grade 0-1 in 22 patients (53.7%), grade 2 in 16 patients (39%), and grade 3 in 3 patients (7.3%). Lower gastrointestinal toxicity was grade 0-1 in 32 patients (78%), grade 2 in 7 patients (17.1%), and grade 4 in 2 patients (4.9%). Treatment was stopped early in 4 patients following administration of 30 to 54 Gy. Median survival for adenocarcinoma histology was 10.3 months (18.6 months in patients alive at analysis; n = 8) with actuarial 1- and 2-year survivals of 38% and 25%, respectively. CONCLUSION: Daily image-guidance during delivery of IMRT for pancreatic carcinoma is clinically feasible. The data presented support the conclusion that safety margin reduction and moderate dose escalation afforded by implementation of these new radiotherapy technologies yields preliminary outcomes at least comparable with published survival data.