Image guided radiotherapy in curative treatment for prostate cancer. 5-year results from a randomized controlled trial (RIC-trial)

Background: Between 2012 and 2015 we conducted a randomized controlled trial in prostate cancer patients comparing weekly 2-D portal imaging versus daily 3-D verification.

Aim: To evaluate the clinical outcomes of image guided radiotherapy by presenting rectal and urinary side effects, health related quality of life and progression free survival after 5-years follow up of a randomized controlled trial.

Methods: We randomized 260 men with intermediate or high-risk prostate cancer to weekly 2-D portal imaging with 15 mm margin from CTV to PTV (Arm A) or daily 3-D cone-beam computer tomography with 7 mm margins (Arm B). Prescribed doses were 78 Gy/39 fractions. All patients received hormonal therapy. Primary end point was patient reported bowel symptoms and secondary outcomes were patient reported urinary symptoms, health- related quality of life and progression free survival.

Results: Of the 216 patients available for analyses at 5 years more than 90 % completed patient reported outcome measures. There were no significant differences between study arms for any single items nor scales evaluating bowel symptoms. There were also no differences in self-reported urinary symptoms nor in health-related quality of life. Symptom scores were low in both study arms. Progression free survival was similar in Arm B as compared to arm A (Hazard ratio 1.01; 95 % CI 0.57 to 1.97).

Conclusions: Our results support that both 2-D weekly and 3-D daily image guided radiotherapy are safe and efficient treatments for PC and emphasize the need to evaluate technological progress in clinical trials with long follow-up.