WASHINGTON (Reuters) – The Pentagon disclosed on Tuesday that U.S. Defense Secretary Lloyd Austin had surgery to treat prostate cancer in December but then developed complications that brought him back to the hospital, where he has remained since Jan. 1. Here’s what has been revealed publicly about Austin’s condition and his course of treatment and what experts say about the illnesses affecting him. WHEN WAS AUSTIN’S PROSTATE CANCER DETECTED AND TREATED? Austin, who is 70, learned he had prostate cancer in December after routine surveillance for the illness via blood tests to monitor levels of…