Hey Terry, of course I agree that mets kill but only because tumors do. It's like saying seeds bring fruit. Of course, that may be true, but not without plants. Tumors cause eventual organ shut down (or in non-tumor blood cancers, complete impairment of proper blood cell production), not mets. If you cannot kill the seeds, but you can kill the plants, and can do so before those seeds you cannot kill can become plants of their own, you have successfully prevented your field from being overrun with the undesirable plants (weeds). But, it seems Direct may also have seed killing properties.
What I'm really unsure of is the extent these former tumors can be dissolved and cleared, and if they leave any scarring which could impair organ function in and of itself. In that case I suppose at some point you simply could not inject a patient's tumors anymore. Though I imagine that would take quite a while...