Below is a synopsis of the 1957 book in question -
Call Me Joe centers on a paraplegic — Ed Anglesey — who telepathically connects with an artificially created life form in order to explore a harsh planet (in this case, Jupiter). Anglesey, like Avatar's Jake Sully, revels in the freedom and strength of his artificial created body, battles predators on the surface of Jupiter, and gradually goes native as he spends more time connected to his artificial body.
The book is in the SCI-FI hall of fame and the author of the novel actually wrote another novel called Avatar.
Wow. That's far - far too similiar to Cameron's film for the writer (or his family) to NOT take legal action. I would. SHUT IT DOWN JAMES - THIS ISN'T GOOD!