Is Yuri as a genre ever referred to to using Katakana or is it only just kanji? I know that the yuri genre is written with kanji and I was wondering, is katakana ever used to write or refer to the genre when used in a discussion. I myself have never seen it, but I wanted to know if anyone who knows japanese has?
EDIT: Rarely. 百合 is more common. The other two seem to be A) part of people's names or B) Lily flowers.

A few searches on google, amazon or any eshop will give you a rough idea.

Just a language note, any word in Hiragana can be written in Katakana. Katakana can be used for emphasis or italics purposes (often loan words but not necessarily).