I think that if someone who has terminal Stage IV cancer wants to help out medical science by contributing to the store of knowledge about different new & untested chemicals they should be able to do so. Who knows whether they may end up making the difference in a cure in a clinical trial.
If one wants to maximize the time they have left with their loved ones just a reminder that chemo of any sort (like in clinical trials) are serious business and can leave one feeling pretty bad on top of the cancer itself (pain management can do a pretty good job there).
My dad chose clinical trials.
If I were in the same spot today as he was I would call Hospice and do whatever I could for as long as I could.
It really is an individual choice for that one person to make...