Abstract
Background: The combination of intensity modulated radiation therapy (IMRT) and image guided radiotherapy (IGRT) plays a significant role in sparing normal tissue during prostate cancer treatment. We report the clinical outcomes of 260 patients treated with high-dose IGRT as well as the toxicity of high-dose IGRT in these patients Materials and methods: From September 2008 to February 2012, 260 men with clinically localized prostate cancer underwent radical radiotherapy.
Two hundred patients were treated with IMRT (78 Gy in 39 fractions) to the prostate and base of seminal vesicles using an adaptive protocol combining cone-beam computed tomography (CBCT) and kilovoltage image matching with individualized safety margin calculation. Sixty patients underwent treatment with the same prescribed dose using RapidArc with a reduced safety margin of 6 mm and daily online matching using CBCT.
Late toxicity was scored prospectively according to the RTOG/FC-LENT scale. Results: Eighteen patients (6.9%) experienced acute grade 2 gastrointestinal toxicity.
There was no acute grade 3 or 4 gastrointestinal toxicity. Thirty-nine patients (15%) experienced acute grade 2 genitourinary toxicity and 6 patients (2.3%) had grade 3 gerourinary toxicity.
Genitourinary toxicity grade 4 was observed in 5 (1.9%) patients, due to installation of a urinary catheter. At a median follow up of 84.2 months, the estimated 7-year cumulative incidences of grade >= 2 gastrointestinal and genitourinary toxicity were 4.4 and 7.1% respectively.
The estimated 7-year prostate specific antigen relapse free survival was 97.1% for low-risk disease, 83.6% for intermediate-risk disease and 75% for high-risk patients. Conclusion: The use of IMRT in combination with IGRT results in a low rate of late toxicity.