The first book I read after being diagnosed was the American Cancer Society's Complete Guide to Prostate Cancer by Bostwick et al. I haven't looked at it since then, but when I read it, having just found out I had PCa, I found it really helped me get a grasp of what was happening to me. I think it dates to about
2005, but maybe it has been updated since then. The Walsh book I read was an earlier version which was hopelessly out of date, but obviously the current edition is highly thought of.