PURPOSE: Recent studies have suggested that extracapsular brachytherapy treatment margins correlate with biochemical control. It is likely that volumetric geographic dosimetric parameters will be more robust than selected radial measurements. Accordingly, we evaluated extracapsular volumetric dosimetric parameters in low-risk patients. MATERIALS AND METHODS: A total of 263 low-risk prostate cancer patients randomized to Pd-103 versus I-125 were implanted with a brachytherapy target volume consisting of the prostate with a 5-mm periprostatic margin. The median follow-up was 4.2 years. All patients were implanted at least 3 years prior to analysis. Within 2 hours of implantation, an axial CT was obtained for postimplant dosimetry. A 5-mm three-dimensional periprostatic anulus was constructed around the prostate and evaluated in its entirety and in 90 degrees segments. Prostate and anular dosimetric parameters consisted of V100/V150/V200 and D90. Biochemical progression-free survival (bPFS) was defined as a PSA < or =0.50 ng/mL after nadir. RESULTS: The Pd-103 and I-125 arms were well-matched in terms of clinical, biochemical, and pathologic presentation. Six-year bPFS was 96.8% versus 99.2% for I-125 versus Pd-103 (P = 0.149). The most recent median posttreatment PSA was <0.04 ng/mL for both isotopes. No significant differences in postoperative anular doses were discerned between bPFS and failed patients. CONCLUSIONS: A postimplant 5-mm, three-dimensional periprostatic anulus provides substantial information regarding dosimetric coverage. However, with a median follow-up of 4.2 years, such volumetric and geographic parameters have not proven useful in predicting biochemical outcome in low-risk patients.
RCT Entities:
PURPOSE: Recent studies have suggested that extracapsular brachytherapy treatment margins correlate with biochemical control. It is likely that volumetric geographic dosimetric parameters will be more robust than selected radial measurements. Accordingly, we evaluated extracapsular volumetric dosimetric parameters in low-risk patients. MATERIALS AND METHODS: A total of 263 low-risk prostate cancerpatients randomized to Pd-103 versus I-125 were implanted with a brachytherapy target volume consisting of the prostate with a 5-mm periprostatic margin. The median follow-up was 4.2 years. All patients were implanted at least 3 years prior to analysis. Within 2 hours of implantation, an axial CT was obtained for postimplant dosimetry. A 5-mm three-dimensional periprostatic anulus was constructed around the prostate and evaluated in its entirety and in 90 degrees segments. Prostate and anular dosimetric parameters consisted of V100/V150/V200 and D90. Biochemical progression-free survival (bPFS) was defined as a PSA < or =0.50 ng/mL after nadir. RESULTS: The Pd-103 and I-125 arms were well-matched in terms of clinical, biochemical, and pathologic presentation. Six-year bPFS was 96.8% versus 99.2% for I-125 versus Pd-103 (P = 0.149). The most recent median posttreatment PSA was <0.04 ng/mL for both isotopes. No significant differences in postoperative anular doses were discerned between bPFS and failed patients. CONCLUSIONS: A postimplant 5-mm, three-dimensional periprostatic anulus provides substantial information regarding dosimetric coverage. However, with a median follow-up of 4.2 years, such volumetric and geographic parameters have not proven useful in predicting biochemical outcome in low-risk patients.
Authors: George Rodrigues; Xiaomei Yao; D Andrew Loblaw; Michael Brundage; Joseph L Chin Journal: Can Urol Assoc J Date: 2013 May-Jun Impact factor: 1.862
Authors: Gregory S Merrick; Wayne M Butler; Peter Grimm; Mallory Morris; Jonathan H Lief; Abbey Bennett; Ryan Fiano Journal: J Contemp Brachytherapy Date: 2013-10-02
Authors: Gregory S Merrick; Ava Tennant; Kent E Wallner; Robert Galbreath; Wayne M Butler; Ryan Fiano; Edward Adamovich Journal: J Contemp Brachytherapy Date: 2017-10-19