The Effect of Dutasteride on Magnetic Resonance Imaging Defined Prostate Cancer: MAPPED—A Randomized, Placebo Controlled, Double-Blind Clinical Trial

Caroline M. Moore, Nicola L. Robertson, Fatima Jichi, Adebiyi Damola, Gareth Ambler, Francesco Giganti, Ashley J. Ridout, Simon R.J. Bott, Mathias Winkler, Hashim U. Ahmed, Manit Arya, Anita V. Mitra, Neil McCartan, Alex Freeman, Charles Jameson, Ramiro Castro, Giulio Gambarota, Brandon J. Whitcher, Clare Allen, Alex Kirkham, Mark Emberton

Dutasteride is licensed for symptomatic benign prostatic hyperplasia, and has been associated with a lower progression rate in low-risk prostate cancer. We have evaluated the effect of dutasteride on prostate cancer volume as assessed by T2-weighted Magnetic Resonance Imaging (MRI). In this randomized, double-blind, placebo-controlled trial, men with biopsy-proven low-intermediate risk prostate cancer (up to Gleason 3+4 and PSA up to 15 ng/ml) who had an MR visible lesion of >/= 0.2ml on T2-weighted sequences were randomized to daily dutasteride 0.5mg or placebo for 6 months. Lesion volume was assessed at baseline, 3 and 6 months, with an image-guided biopsy to the lesion at study exit. The primary endpoint was percentage reduction in lesion volume over 6 months. This trial was registered with the European Clinical Trials register (EudraCT 2009-102405-18). Forty-two men were recruited between June 2010 and January 2012. In the dutasteride group, the average volumes at baseline and 6 months were 0.55ml and 0.38ml respectively, and the average percentage reduction was 36%. In the placebo group, the average volumes at baseline and 6 months were 0.65ml and 0.76ml respectively, and the average percentage reduction was -12%. The difference in percentage reductions between groups was 48% (95% CI 27.4-68.3%. p< 0.0001). The most common adverse event was deterioration in erectile function (25% in men randomized to dutasteride, 16% in men randomized to placebo). Dutasteride was associated with a significant reduction in prostate cancer volume on T2 weighted MRI images compared to placebo.