Hypofractionated dose painting IMRT using 20 fractions for intermediate to high-risk localized prostate cancer: Two-year outcome data (BIOPROP20, NCT02125175).

Abstract

59 Background: Prostate dose painting (boosting intra-prostatic tumour volumes) may improve biochemical relapse-free survival similar to whole organ dose-escalation without the associated increased toxicity. We present a pre-defined secondary endpoint of 2 year outcome for patients at one of two UK centres in a phase II trial (BIOPROP20) on dose-painting radiotherapy for intermediate to high risk patients treated with 60Gy/20# and concurrent 68Gy boost. Methods: Pinnacle software was used for VMAT planning and boost volumes were outlined by18F choline PET/CT and mpMRI. Patients with positive lymph nodes also had concurrent pelvic radiotherapy of 45Gy with boost to 50Gy. Patients were followed up until year 2 with PSA and toxicity scores. Results: Overall 56 patients were treated, 5 with pelvic radiotherapy. Median age and PSA was 67.5 years (range 50 - 77) and 10.0ng/ml (3.9 - 39.4). All patients had tumour volumes > 10mm diameter on pre-biopsy mpMRI. 13 and 43 patients had intermediate and high risk disease. Median % LN risk was 18% (15 - 40). ADT duration was 6 months, 2 years, and 3 years for 42, 5, and 9 patients. At the 2 year follow up review, no grade 3 late toxicity was observed. For prostate only dose painting, grade 2 GU and GI toxicity was noted in 6% and 2% respectively. For prostate and nodal dose painting, no grade 2 toxicity was noted. Median IPSS score was 5 and 9, and median PSA was 0.3 and 0.1, in the two groups respectively. 1 patient had biochemical and metastatic relapse at 18 months (prostate, pelvic nodes and bone metastasis) and 1 patient had died of unrelated disease. Conclusions: Prostate radiotherapy with hypofractionated dose painting schedule of 60Gy/20# with 68Gy boost to intra-prostatic lesions was well tolerated at 2 years follow up. Clinical trial information: NCT02125175. [Table: see text]