Abstract: PD55-01
Sources of Funding: None

Introduction

Dutasteride 0.5mg daily is licensed for lower urinary tract symptoms (LUTS) in men with an enlarged prostate, and some men on active surveillance will be taking dutasteride for LUTS. _x000D_ This study was designed to describe the effects of daily 0.5 mg dutasteride for 6 months, compared to placebo, on men with biopsy proven prostate cancer and an MR lesion at baseline. We report here the effect of dutasteride on the conspicuity of tumor on diffusion-weighted imaging (DWI) sequences to answer the question: does dutasteride make visible lesions less conspicuous on DWI?._x000D_

Methods

Institutional review board approval and patient informed consent were obtained. We retrospectively analyzed 37 men, randomized to 6 months of daily dutasteride 0.5 mg (n=18) or placebo (n=19), undergoing 3T multi-parametric Magnetic Resonance Imaging (mpMRI) scans at baseline and 6 months. Images were reviewed by 2 experienced uro-radiologists in consensus blind to treatment allocation and clinical information. Mean apparent diffusion coefficient (ADC) from DWI of peripheral (PZ) and transition (TZ) zones, and MR-suspicious lesions were compared between the dutasteride and placebo groups at baseline and 6 months (T test; p < 0.05 significant). _x000D_ We defined the term conspicuity as the mean ADC of the PZ divided by the mean ADC of the lesion. We assessed the change in conspicuity over 6 months and analyzed the differences in the dutasteride and placebo groups._x000D_

Results

All men had at least one visible lesion at baseline and 6 months on DWI. There were no significant differences at 6 months for ADC values in the PZ, TZ and lesions between the two groups (placebo vs dutasteride). There was a significant decrease in mean conspicuity in the dutasteride group (1.54 at baseline vs 1.38 after 6 months; p = 0.025)._x000D_ Changes in mean absolute tumor ADC and conspicuity between the placebo and dutasteride groups were demonstrated (- 0.03 vs 0.08, p =0.033) and (0.11 vs - 0.16, p = 0.012), respectively. _x000D_ There was a significant percentage increase in tumor ADC and a significant decrease in the conspicuity for the dutasteride group when compared to men in the placebo group (8.6% vs - 2.3%, p = 0.048) and (- 9.9% vs 9.3, p = 0.013), respectively. _x000D_

Conclusions

Dutasteride reduces tumor ADC and conspicuity. A lower biopsy threshold would make sense in men who are on dutasteride for LUTS and are undergoing MRI assessment for prostate cancer.

Funding

None