A system and method permit monitoring and location of a route in vivo and a visible image of that route for retrograde perfusion of a tumor with a therapeutic agent. Once the route is located, the path for flow of therapeutic agent to the tumor is confirmed as being a closed loop. The therapeutic agent is then introduced into the closed loop through retrograde perfusion to treat the tumor. The number of types and amounts of treating agents may be adjusted and observed as the treatment is in progress.