Giving a higher dose of radiation to the dominant tumour nodule within the prostate is hypothesized to improve tumour control. This trial will assess whether this technique, delivered in 5 treatments, can be delivered without increasing side effects.

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.

Inclusion Criteria:

Prostate cancer patients with any of the following:

• PSA 20-40
• Gleason grade 4+3 or higher
• Stage T3a

Exclusion Criteria:

• Nodal or metastatic disease
• PSA>40
• Stage T3b or higher