Phase I–II Study of Hypofractionated Simultaneous Integrated Boost With Tomotherapy for Prostate Cancer
Received 28 May 2008; received in revised form 7 August 2008; accepted 7 August 2008. published online 03 December 2008.
Purpose
To report planning and acute toxicity data of the first 60 patients treated within a Phase I–II study with moderate hypofractionation by image-guided helical tomotherapy.
Methods and Materials
Various clinical target volumes (CTVs) were defined: CTV1—pelvic nodes; CTV2—upper portion of seminal vesicles; CTV3—lower portion of SV; CTV4—prostate; overlap between planning target volume (PTV) 4 and rectum. Different doses to each PTV were simultaneously delivered in 28 fractions. For 31 low-risk patients: 56.0, 61.6, and 71.4 Gy for PTV2–4, respectively; for 20 intermediate-risk patients: 51.8, 61.6, 65.5, and 74.2 Gy for PTV1–4, respectively; for 9 high-risk patients: 51.8 and 65.5 Gy for PTV1–2 and 74.2 Gy for PTV3–4. For all patients, the dose to overlap was 65.5 Gy.
Results
The mean fraction of rectum receiving more than 65 Gy (V65) and rectal Dmax were 10% and 70.8 Gy respectively. In cases of pelvic node irradiation, the intestinal cavity (outside PTV) receiving > 45 and 50 Gy was 86 and 12 cc, respectively. A homogeneous dose distribution within each PTV was guaranteed. Acute genitourinary toxicity according to RTOG scoring system was as follows: 21/60 (35%) Grade 1, 12/60 (20%) Grade 2, 2/60 (3%) Grade 3. Acute rectal toxicities were: 18/60 (30%) Grade 1. Twelve (20%) patients showed Grade 1 upper intestinal toxicity (uGI). No patients experienced ≥ Grade 2 acute rectal or uGI side effects.
Conclusions
This study shows excellent results with regard to acute toxicity. Further research is necessary to assess definitive late toxicity and tumor control outcome.
Reprint requests to: Nadia Di Muzio, M.D., Radiotherapy Department, Scientific Institute San Raffaele, via Olgettina 60, 20132 Milan; Tel: (+39) 02-26437643; Fax: (+39) 02-26437639
ABSTRACT