Pilot Study of Whole Gland Salvage HDR Prostate Brachytherapy for Locally Recurrent Prostate Cancer

Radiation therapy is considered a standard treatment option for the management of localized prostate cancer. Among the 20-30% of patients who recur, there is no consensus on the optimal salvage therapy. Salvage options available for isolated local recurrence include; temporary or permanent implantation of radioactive seeds into the prostate, complete removal of the prostate gland, use of low temperatures to treat the disease (cryotherapy), and high frequency ultrasound to treat the disease. There are risks of complications associated with all these treatments, and there is presently no consensus as to which treatment is the best. The aim of this pilot study is to look at the feasibility and toxicities of whole gland salvage treatment of the prostate using temporary implantation of radioactive seeds into the prostate.

Radiation therapy is considered a standard treatment option for the management of localized prostate cancer. Among the 20-30% of patients who recur, there is no consensus on the optimal salvage therapy. Salvage options available for isolated local recurrence include; temporary or permanent implantation of radioactive seeds into the prostate, complete removal of the prostate gland, use of low temperatures to treat the disease (cryotherapy), and high frequency ultrasound to treat the disease. There are risks of complications associated with all these treatments, and there is presently no consensus as to which treatment is the best. The aim of this pilot study is to look at the feasibility and toxicities of whole gland salvage treatment of the prostate using temporary implantation of radioactive seeds into the prostate. Reports of the efficacy and toxicities of whole gland salvage HDR brachytherapy for local recurrence after external beam radiation therapy are limited to single-institution studies with small sample sizes. Given that our institution has the highest volume of prostate brachytherapy cases in Ontario and that we receive a significant number of referrals from other cancer centres for brachytherapy, this study will aim to add to the literature and help guide salvage therapy practice within our institution.

Locally recurrent prostate cancer Whole gland HDR brachytherapy administered Whole gland dose=10.5Gy x 2 fractions delivered one week apart GTV dose=13.5Gy x 2 fractions delivered one week apart

Inclusion Criteria: Biopsy confirmed locally recurrent prostate adenocarcinoma > 30mths after completion of XRT by stereotactic transperineal biopsy Staging T2-weighted, DWI- and DCE- MRI that demonstrates recurrence confined to prostate, and correlates with stereotactic transperineal biopsy Previous external beam radiotherapy for prostate cancer with standard/conventional fractionation (1.8-2.0 Gy per fraction), or moderate hypofractionation (2.4-3.4 Gy per fraction). Staging CT or MRI (abdomen and pelvis) and bone scan are negative for metastases IPSS < 15 Baseline (post XRT) serum PSA < 10ng/mL Prostate volume as measured by TRUS < 50cc ECOG performance status 0-1 Exclusion Criteria: Disease adjacent to the urethra as visible on MRI Any of the following prior therapies; TURP, radionuclide prostate brachytherapy, prostatectomy or prostatic cryosurgery, HIFU, bilateral orchiectomy, chemotherapy for prostatic carcinoma Evidence of castrate resistance (defined as PSA > 3ng/mL while testosterone is < 1.7nmol/L) Patients could have been on combined androgen blockade with initial XRT but are excluded if this was started due to PSA progression