How come some people say 'Qur'an' instead of 'The Qur'an'?

Sometimes I see people ask questions like, "What does Qur'an say about..." even college professors use this type of grammar when using the word Qur'an. What is the direct translation of Qur'an in english? Why not say 'the' Qur'an? Is there a grammatical rule or reason for this?