Alvarez knocks out Khan: Mexican fighter retains middleweight title with stunning stoppage in Las Vegas
He last fought in February where he defeated opponent Dada 5000 only for the win to be overturned after he tested positive for a banned steroid.
He was due to headline another Bellator MMA event in London next month.
Mr Slice became widely known to fight fans after videos of his street brawls where he destroyed opponents in unsanctioned bouts started to appear online in 2003.