Most GPs are totally unqualified to do that sort of work anyway. They look at something on your skin and really have no idea what it is, and whether it is normal or not. Mine couldn’t tell simple seborrheic keratosis when he saw it.
I have an excellent dermatologist here in Manhattan, who is by no means cheap. He will glance at something and tell you exactly what it is.
Before too long you’ll be able to get cancer screening involving only laying down on an examination table while a dog sniffs about you for a few minutes. I’ve read claims that a trained dog can even detect melanoma before there are any outward manifestations.
Dogs can also detect some forms of internal cancers on the breath.
http://www.dogsdetectcancer.org/dogs-detect-cancer-blog/can-dogs-smell-cancer