Salvage image-guided radiotherapy to the prostate after cryotherapy failure.

Abstract

e637 Background: Cryotherapy is used in increasing frequency for the primary treatment of localized prostate cancer. While it is known that local recurrence can occur in > 20% of patients treated with primary cryotherapy there is a paucity of data on salvage treatments after failure. The use of external beam radiation therapy is an attractive option after cryotherapy failure but there is little data on efficacy and toxicity. We evaluate our data on a group of patients treated with image-guided dose-escalated radiotherapy (IGRT) at our institution. Methods: An IRB-approved database of patients treated with IGRT for prostate cancer from 2005 to 2013 was used to identify patients who underwent primary cryotherapy followed by salvage IGRT. Patients’ EMR were reviewed for age, cryotherapy-to-salvage interval, pre/post-salvage PSA and Gleason score (GS). All patients were treated with dose-escalated IGRT using standard treatment margins of 3 mm posterior and 7 mm in all other directions and daily CBCT or kv imaging to implanted fiducial markers. Narrative notes were used to identify GU/GI toxicity and scored according to CTCAE v4.03. The Phoenix definition of nadir + 2 was used to determine disease control following RT. Results: 5 patients were identified within the study period as having received salvage RT after primary cryotherapy. Mean age at the time of salvage RT was 74 (range 65-80). Median cryotherapy-salvage interval was 49 months (range 25-97) and prior to RT patients had GS of 7 (n = 3) or 8 (n = 2) and mean PSA of 8.1 ng/mL (range 4.2-14.38). Median total dose and follow-up were 76.7 Gy (range 75.6 – 81.0) and 52 months (range 6-63). One patient’s PSA did not decline post-RT and developed metastases while four patients responded post-RT with one experiencing biochemical recurrence after 30 months. No patients had acute GU/GI toxicities grade 2 or higher; one experienced late grade 2 GU toxicity (dysuria) which resolved with medication. There were no late grade 3 toxicities. Conclusions: High-dose radiotherapy as salvage treatment after cryotherapy failure is tolerated without significant GU or GI toxicities. Additionally, salvage IGRT is a viable option for long-term biochemical control in cases of local recurrence and warrants additional study.