Stereotactic Hypofractionated Accurate Radiotherapy of the Prostate (SHARP), 36.25 Gy in Five Fractions for Localized Disease: A Case Series Results from King Faisal Specialist Hospital, Saudi Arabia.

PURPOSE: To evaluate the feasibility, efficacy and toxicity of stereotactic hypofractionated accurate radiotherapy (SHARP) for localized prostate cancer.

METHODS AND MATERIALS: The current series of SHARP included six patients with localized prostate cancer treated with 36.25 Gy in 5 fractions by Cyber-knife. Non-coplanar conformal fields and daily stereotactic localization of implanted fiducials were used for treatment. Acute and Late Genitourinary (GU) and gastrointestinal (GI) toxicity were evaluated by Common Toxicity Criteria (CTC). Prostate-specific antigen (PSA) values and self-reported sexual function were recorded at 3 months interval at first two years then every 6 months thereafter.

RESULTS: The median follow-up is 32 months. Acute toxicity Grade 1 (GU) noted in four cases and two cases were Grade II; Grade I (GI) was in five cases and one patient in Grade II; also with regards to late toxicity, Grade 1 (GU) and (GI) was present in all cases. No patient has experienced grade 3 or greater acute or late toxicity. Regarding sexual activity, three patients reported impotency before and after therapy and all of them have insulin dependent diabetes mellitus and ischemic heart disease; fourth patient has developed impotence and the other two patients developed no changes as before radiation. The mean basal PSA was 8 ng/ml and became 0.658 ng/ml.

CONCLUSIONS: SHARP for localized prostate cancer is feasible with minimal acute or late toxicity. Dose escalation should be possible. MRI guided target volume delineation and intrafraction prostate motion tracking with real-time beam adjustment are critical for safe high dose per fraction prostate SBRT.