Prostate MRI-Bx may ID partial gland ablation candidates

Boston-Information from magnetic resonance imaging (MRI) and systematic biopsy may be used to identify candidates for partial gland ablation among men with recurrent localized prostate cancer after radiation therapy, researchers from Memorial Sloan Kettering Cancer Center (MSKCC) reported at the AUA annual meeting in Boston.

The feasibility of using the MRI and systematic biopsy characteristics for determining the topographic location of the tumor in the prostate was investigated in a study including 77 men who had a tumor map created from entirely submitted, whole-mounted specimens after undergoing salvage radical prostatectomy. Using a priori clinical criteria that required the presence of biopsy-proven unilateral disease concordant with a region of interest on MRI and absence of MRI findings suspicious for extracapsular extension, seminal vesicle invasion, or lymph node involvement, 15 of the 77 patients were identified as being eligible for partial gland ablation.

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Use of the clinical criteria for patient selection demonstrated 100% specificity-all 15 patients were confirmed to have unilateral cancer without adverse pathologic features when their tumor maps were reviewed by a single, blinded pathologist. The selection approach had a sensitivity of 65% because eight men who would have been eligible for partial gland ablation according to tumor map review were not identified using the clinical criteria.

“Men with prostate cancer recurrence after radiation therapy are not uncommon and more often treated with androgen deprivation therapy. Salvage partial gland ablation can be a potential treatment alternative in carefully selected patients with organ-confined recurrent cancer. Our findings support the feasibility of using MRI and biopsy characteristics to select patients for salvage partial gland ablation,” said first author Arjun Sivaraman, MD, a Society of Urologic Oncology fellow at MSKCC, New York, who worked on the study with Behfar Ehdaie, MD, MPH, and colleagues.

“However, we recognize that our study is limited by its small population. Therefore, definitive recommendations about use of this technique are pending further investigation. Accumulating a larger number of cases will take time, however, considering that radical prostatectomy is not frequently performed in the salvage setting,” Dr. Sivaraman told Urology Times.

Continue to the next page for more on this study.

The 77 men included in the study were identified from among 225 patients who had undergone salvage radical prostatectomy at MSKCC from 2000 to 2014. The remaining 148 men did not have a tumor map of the whole-mount specimen. A sensitivity analysis comparing the included and excluded groups showed that the included patients were representative of the entire cohort.

The 15 men who were identified as eligible for partial gland ablation based on their clinical characteristics had a mean age of 60 years. Median time from primary radiotherapy was 48 months. The index lesion (largest tumor mass with the highest Gleason grade) was located in the mid-gland in all men with extension to the apex in 77% of the men and to the base of the prostate in 15%.

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“The index lesion appears to be located closer to the urethra, and the median distance of the index tumor to the urethra was 0.5 cm,” Dr. Sivaraman said.

“Based on these findings, we would propose that when salvage focal treatment is considered, the strategy should be a complete hemi-gland ablation including the periurethral tissue.”

Ten of the 15 men identified as eligible for partial gland ablation based on clinical criteria had undergone external beam radiation and the other five had brachytherapy. Dr. Sivaraman acknowledged that the quality of the MRI may be affected by prior radiotherapy seeds.

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