How the rise of testosterone therapy in men was inspired by lizard research with David Crews.

A chance encounter in 1975 with David Crews in Harvard Square led to 3 years of research in his lab, investigating the role of testosterone (T) in male sexual behavior of the lizard, Anolis carolinensis. In 1988 when I began my practice as a urologist and specialist in men's health, my research experience with lizards led me to offer testosterone therapy (TTh) to men suffering with symptoms of testosterone deficiency, despite the universal belief that TTh caused prostate cancer (PCa). My investigation of this topic over 30+ years has led to revolutionary changes in the diagnosis and treatment of men with testosterone deficiency and our understanding of the biology of testosterone and PCa. Today, it is routine for men successfully treated for PCa to receive TTh, a remarkable fact given that standard treatment for men with advanced PCa has been androgen deprivation for the last 80 years. Our research showed low T was not protective for PCa; TTh did not appear to worsen PCa for various cancer stages; and provided the theoretical framework for understanding why androgen deprivation shrinks PCa tumors, yet TTh appears to not cause PCa growth under most conditions. This is based on the Saturation Model, which recognizes there is a finite ability of androgens to stimulate PCa growth, which becomes maximal at low T concentrations. David Crews was an outstanding mentor-the lessons I learned from him inspired a lifetime of work, which in turn led to improved quality of life for millions of men.