Introduction

Traditional whole gland treatment for prostate cancer is complicated by urinary incontinence and erectile dysfunction in up to 30-50% of the patients(1, 2). MR Guided Transurethral US has been previously shown to be safe and effective for whole gland prostate ablation for patients with prostate cancer and might be a novel whole gland ablation technique. However, prostatectomy remains the standard of treatment for patients with more aggressive disease. But, a significant number of patients have other comorbidities, making them not good candidates for surgery. This study aims to evaluate the safety and efficacy of whole gland MRI-guided transurethral ultrasound ablation (TULSA) for prostate cancer treatment in patients with low-intermediate grade prostate cancer.

Methods

This IRB approved, HIPAA compliant study included 9 men (45 to 80 years) with biopsy-confirmed PCa, clinical-stage <T2b, Gleason score (GS) ≤ 3+4, PSA ≤ 15 ng/ml and prostate volume ≤ 90 cc. The whole prostate was ablated with 3T MRI guided TULSA along with a rectal cooling probe. Patients were followed-up (F/U) at 1, 3, 6, and 12 months after the treatment with measurements of PSA and 3T mpMRI. The prostate non-perfused volume (NPV) was measured on contrast-enhanced T1-weighted images at each F/U. A paired T-test was used to compare each subject's pre-treatment measurements to their last value F/U measurement (p<0.05 considered significant). TRUS-guided 10-core prostate biopsy was performed 12 months after ablation.

Results

In 17 PCa lesions from 9 patients, 8 were GS 3+3, and 9 were 3+4. The mean prostate ablation time was 89 min. (range 30-120 min). All of the cases were clear of the lesion on biopsy 12 months after treatment. There were no immediate intra-procedural or post-procedural complications. Mean prostate volume on T2-weighted MRI decreased from 46cc at baseline to 32cc (29%), 24cc (49%), 21cc (54%) and 13cc (70%) on 3, 6, & 12-month F/U, respectively (p=0.01). The mean prostate NPV decreased from 33.7cc (range 13-83cc) to 21cc (38.3%), 15cc (56.6%), 11cc (68.8%) and 2cc (94.2%) on 1, 3, 6, and 12-month F/U, respectively. Mean PSA density (PSAD) decreased from 0.19 ng/ml2 before treatment to 0.02 on 1-month F/U and then increased gradually to 0.09, 0.15 and 0.06 at 3, 6 and 12-month F/U, respectively. The mean ADC value decreased 7.4% from 1460 mm-6/s2 ± 117 at baseline to 1351 mm-6/s2 ± 130 on the 12-month F/U (p=0.079). The mean T2W decreased 61.9% from 374 ms ± 261 at baseline to 143 ms ± 73 on the 12-months F/U (p=0.052). The mean T1-weighted contrast decreased by 22.2% from 427 ms ± 312 at baseline to 332 ± 81 on the 12-month F/U (p=0.378).

Discussion

In this study, we have found that MR guided transurethral ultrasound was safe and resulted in a significant decrease in prostate volume at 1, 3, 6, and 12 months with a corresponding significant decrease in PSAD, NPV, and PSA. In Bonekamp et al study, 88% reduction in prostate volume at 12 months F/U was reported similar to our study. Moreover, ADC decreased in the post ablated prostate, as shown in prior studies. Jakob et al(3) reported decreases in post-treatment ADC values for non-treated fibroid tissue (1685mm-6/sec2 ± 468) compared to post-treatment ADC values for fibroid tissue (1078 mm-6/sec2 ± 293) (p=0.001). T2-weighted imaging is susceptible to differences in the area of the magnetic domain and is helpful for considering ablated texture(4). Wang et al(5) have reported that average T2 (57.8 msec ± 25.3) in the pre-ablation area was significantly higher than T2 (38.9 msec ± 14.1) in the same area after treatment (P=0.03). Westin et al(6) also reported increases in T2 values in areas of ablation from (94.99 msec ± 25.07) at the baseline to (93.41 msec ± 35.19) 3 months after ablation and, (105.27 msec ± 63.67) 12 months after treatment.

Conclusions

In conclusion, the new MRI-guided TULSA procedure treated the whole prostate gland in an outpatient setting without significant complications in patients with low-intermediate grade PCa, with a significant, the predictable decrease in prostate volume and PSA density, and with considerable changes in mpMRI parameters at multiple F/U time points.

Acknowledgements

No acknowledgement found.

References

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