Since I have a soft spot for the poor kids with cancer, they would get it first and work up from there. I would make sure every hospital and cancer center receives it by any means possible. I would spend every last dollar I have to make sure it's distributed equally to everyone who needs and wants it.
Obviously ... Me first.
Next ... Anybody who helped me.
Then I'd "vaporize" it, and "bomb" undeveloped nations with it.
Let the developed nations pay for it. They're the ones releasing all the poisons causing the majority of cancers.
I've lost a few people I love to different kinds of cancer. I have no idea what types will affect people I care for in the future or possibly myself. So just all of them at once then ... BAM!