When we refer to a performing art in general, we can leave out the definite article, e.g. Are you
interested in (the) cinema/ballet/opera/theatre? But: Would you like to come to the cinema/
ballet/opera/theatre with us next week? [particular performance]
interested in (the) cinema/ballet/opera/theatre? But: Would you like to come to the cinema/
ballet/opera/theatre with us next week? [particular performance]