Based on a number of parameters, words can be substituted at varying rates within a sentence, however it is non-deterministic.
Given the idiomatic nature of language, errors may still occur where a word is translated into a synonym which may not be contextually valid.
The author of the article should complete a sufficient number of arguments in support of his thesis before he starts writing.
There are many paraphrasing tools that claim this, but in most cases they are either completely innacurate, not work at all or are full of annoying bugs.
As medical terminology is fundamental to the discourse of health sciences, it would be reasonable to classify these words as preferentially immutable.
It also has to bring something original and interesting to this subject.