Medications targeting androgen receptor activity (eg finasteride) or smooth muscle contractility (eg doxazosin) do not resolve lower urinary tract symptoms indicative of lower urinary tract dysfunction in an important subgroup of men. Recently fibrosis has been implicated as another pathobiology contributing to male lower urinary tract symptoms but to our knowledge no systematic studies have been done to assess fibrosis in the context of medical treatment. We determine whether fibrotic changes in the prostate transition zone are associated with an increased risk of clinical progression in participants treated with doxazosin, finasteride or finasteride plus doxazosin in the MTOPS (Medical Therapy of Prostatic Symptoms) study.