Location of Local Recurrence After MRI-Guided Partial Prostate Brachytherapy Targeting Only the Peripheral Zone: Implications for Focal Therapy

149 Background: Prostate cancer local recurrences usually occur at the same site as the dominant primary tumor in patients treated with radiation therapy to the whole gland. We characterized location of local recurrences in patients who were treated with MRI Guided Partial Brachytherapy in which only the peripheral zone was targeted. Methods: We retrospectively reviewed ten patients with initial cT1c, Gleason score 3+4 or less prostate cancer who developed biopsy proven local recurrences and had available imaging after MRI Guided Partial Brachytherapy targeting the peripheral zone from 1998 to 2006. All 10 patients had 1.5T endorectal coil MRI at diagnosis, performed primarily for staging and not for tumor localization, while at recurrence 8 had 3T endorectal coil MRI and 2 had 1.5T endorectal coil MRI. Scans consisted of at least T1 and T2 sequences. Two radiologists (C.T. and T.P.) blinded to clinical data reviewed diagnosis MRI scans together and quantified likelihood of tumor on a 1 to 5 scale in each section of an eight part prostate in both pre-treatment and recurrence scans. Local recurrence was judged to be in the same location as the baseline tumor if at least 50% of the tumor location overlapped. Results: Only 3 of 10 patients had local recurrences at the same location as the baseline tumor with a mean overlap of 64%. 7 of 10 patients had local recurrences at a different location with a mean overlap of 5%. 5 of 10 patients had recurrences in the central zone of the prostate which did not definitively show tumor on review of the initial 1.5T staging scan. Conclusions: After MRI-guided brachytherapy targeting only the peripheral zone in men initially staged with 1.5T MRI, 50% of the local recurrences occurred at the non-targeted central zone, raising the possibility that focal therapy directed only at the dominant tumor will result in increased out-of-field recurrences. Whether the superior ability of modern 3T multiparametric MRI to detect and precisely localize occult prostate cancer foci will reduce this risk is the subject of current study.

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Long-term outcomes of magnetic resonance image-guided partial prostate brachytherapy for favorable-risk prostate cancer.

Journal of Clinical Oncology ◽

10.1200/jco.2018.36.6_suppl.138 ◽

2018 ◽

Vol 36 (6_suppl) ◽

pp. 138-138

Author(s):

Martin T. King ◽

Paul L. Nguyen ◽

Ninjiin Boldbaatar ◽

Clare Mary Tempany ◽

Robert A. Cormack ◽

...

Keyword(s):

Prostate Cancer ◽

Local Recurrence ◽

Peripheral Zone ◽

Prostate Brachytherapy ◽

Specific Mortality ◽

Risk Prostate Cancer ◽

Biochemical Progression ◽

Cancer Specific Mortality ◽

Mri Guided

138 Background: To report long-term outcomes of magnetic resonance image-guided partial prostate brachytherapy of the peripheral zone. Methods: We conducted an institutional-board approved retrospective review of all men who underwent 0.5 Tesla GE Signa SP MRI-guided partial prostate brachytherapy to the peripheral zone. We estimated actuarial rates of biochemical progression (nadir +2 definition), as well as cumulative incidences of biopsy proven local recurrence, distant metastasis, and prostate cancer specific mortality. Fine and Gray’s competing risk regression was utilized in order to evaluate clinical factors associated with times to metastasis and prostate cancer specific mortality. Results: Between 1997 and 2008, 354 men underwent MRI-guided partial prostate brachytherapy. The numbers of patients with low and intermediate risk disease were 295 (83%) and 59 (17%), respectively. Sixty-seven (19%) patients received supplemental external beam radiotherapy. The median follow-up was 8.6 years. For National Cancer Center Network (NCCN) low risk-disease, 8-year estimates of biochemical progression, local recurrence, metastasis, and prostate cancer specific mortality were 23.5% (17.4-29.1), 6.4% (3.6-10.2), 2.0% (0.6-4.8), and 0%. Corresponding estimates for intermediate risk disease were 51.2% (31.3-65.4), 21.2% (10.2-34.9), 6.6% (1.7-16.3), and 5.4% (0.9-16.2). Twenty of 45 biopsy proven local recurrences occurred outside of the implanted peripheral zone. Of the 22 patients who developed distant metastases, 14 events occurred more than 10 years from therapy. On multivariate analyses, biopsy proven local recurrence was the only factor to demonstrate a significant association with metastasis (hazard ratio 2.50; p = 0.05) and a trend with prostate cancer specific mortality (5.02; p = 0.09). Conclusions: MRI-guided partial prostate brachytherapy to the peripheral zone in men with favorable risk prostate cancer is suboptimal with respect to long term cancer control outcomes. Additional studies using contemporary MRI techniques including 3 Tesla based multi-parametric imaging and fusion biopsy may lead to improved outcomes.

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Long-term results of MRI-guided partial prostate brachytherapy for favorable-risk prostate cancer: Implications for focal therapy.

Journal of Clinical Oncology ◽

10.1200/jco.2012.30.5_suppl.114 ◽

2012 ◽

Vol 30 (5_suppl) ◽

pp. 114-114

Author(s):

Paul Linh Nguyen ◽

Ming-Hui Chen ◽

Yuanye Zhang ◽

Clare M. Tempany ◽

Robert A Cormack ◽

...

Keyword(s):

Multivariable Analysis ◽

Peripheral Zone ◽

Focal Therapy ◽

Low Risk ◽

Long Term Results ◽

Prostate Brachytherapy ◽

Psa Failure ◽

Psa Velocity ◽

Mri Guided

114 Background: To report long-term results of MRI-guided partial prostate brachytherapy and propose a definition of biochemical failure following focal therapy Methods: From 1997-2007, 318 men with cT1c, PSA < 15, Gleason ≤ 3 + 4 prostate cancer received MRI-guided brachtherapy in which only the peripheral zone was targeted. To exclude benign PSA increases due to prostatic hyperplasia, PSA failure was defined as nadir + 2 with PSA velocity >0.75 ng/mL/year. Cox multivariable analysis was used to determine factors associated with PSA failure. Results: After a median follow-up of 5.1 years (interquartile range: 2.8 to 7.3, maximum 12.1), 26 men failed. While 36 patients met nadir+2 criteria, all eight biopsy-proven local recurrences were among the 26 men who also had a PSA velocity >0.75 ng/mL/year. On multivariable analysis, having intermediate vs. low-risk disease (adjusted HR: 4.4 [95%CI: 1.3-5.5], p<0.001) was the only factor significantly associated with an increased risk of PSA failure. PSA failure-free survival at 5 and 8 years was 95.6% and 90.0% for low risk, and was 73.0% and 66.4% for intermediate risk, respectively. Conclusions: MRI-guided brachytherapy targeting the peripheral zone produced comparable cancer control rates to whole-gland treatment in men with PSA-detected low-risk disease, but may not be adequate for men with “favorable” intermediate-risk disease. Requiring a PSA velocity>0.75 in addition to nadir+2 may be a more appropriate way to define biochemical failure after therapies that target less than the whole gland.

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