(Reuters) – GameStop Corp, the worlds largest retailer of videogame products, said Chief Executive Paul Raines underwent an unexpected surgery last week for a small cancerous brain tumor. Raines, who will be undergoing chemotherapy, will restrict his travel during the expected six week of treatment, the company said in a regulatory filing on Tuesday. (http://1.usa.gov/1BxwaFG) GameStop also said the six week treatment period will not interfere with Raines continued leadership of the company. (Reporting By Lehar Maan in Bangalore; Editing by Joyjeet Das)