The point of that xkcd comic is that cancer drugs need to be safe as well as effective. A patient whose cancer cells are all dead is not better off if he is dead also.
I read the recipe for the salve and it does not appear to be something that would kill a patient. In fact, you could eat the medicine and it wouldn't hurt you; it's onions or leeks, garlic, wine, bile salts, and some small amount of copper. According to TFA the lab where they tested this smelled like garlic and people thought they were cooking food in the lab.
I'd be willing to have this stuff put on my skin.
P.S. I'm excited by the new technology being called "nanobots". (I think "nanobots" might be overselling what it is, but they didn't ask me.) A nanoscale cylinder is made that can hinge open; some drug is placed inside; and two latches hold it shut. The latches are designed to open only in the presence of a specific protein, such as a specific cancer cell type. Thus we have a nanoscale "robot" that can do exactly two things: it can open when it bumps into a specific cell type, and it can close again when it's away from the specific cell type.
This is exciting because it decouples the two problems of treating cancer: you need to kill the cancer cells and not hurt the patient. With this, you could use a very effective anti-cancer medicine that is as dangerous as a handgun bullet, but make sure that only a nanodose is delivered, and only to the cancer cells (I guess with high but not perfect accuracy).
I tried to find out more about the human trial, but couldn't find anything beyond the video linked in the above article. If these nanobots really do get tested on a human and he really has his life saved by them, I expect significant news coverage. The claim is that the guy would be dead by summer with conventional treatment, so if it's real we won't have to wait more than a few months to read more about it.