Here's why:
* "Communism" is a complete word in itself, describing a political and economic ideology.
* Prefixes are typically used to create new words with slightly modified meanings.
However, you could use "communism" as part of a compound word:
* Communism-related: This could be used to describe something related to communism, such as "communism-related literature".
* Communism-inspired: This could describe something inspired by communist ideals, such as "communism-inspired art".
It's important to note that these are not official words, but rather ways to use "communism" in compound phrases.