The SPARC Trial: Stereotactic Prostate Ablative Radiotherapy Using Cyberknife

Aim To assess if a focal boost can be delivered to the dominant tumour nodule alongside 36.25 Gy in 5 fractions to the whole prostate gland. Primary end-point: Acute toxicity (Radiation Therapy Oncology Group (RTOG), International prostate symptom score (IPSS)) Secondary end-points: Prostate specific antigen (PSA) nadir and 2-year biochemical control Late toxicity (IPSS, RTOG, International index of erectile function (IIEF-5)) Quality of life (EQ5D scale) Inclusion criteria * Prostate cancer patients with any of the following: * PSA\>20 * Gleason grade 4+3 or higher * Stage T3a * Exclusion criteria * Nodal or metastatic disease * PSA\>40 * Stage T3b or higher Study interventions This is a phase II study which will recruit 20 patients. A dose of 36.25 Gy in 5 fractions will be delivered to the whole prostate with a simultaneous integrated boost up to 47.5 Gy in 5 fractions or to the highest dose possible within dose constraints. The boost volume will be defined on the multiparametric magnetic resonance scan by the specialist radiologist.