The man behind the Subway brand died just weeks after celebrating the company's 50th anniversary.

Subway founder and CEO Fred DeLuca died on Monday evening at the age of 67, the company confirmed on Tuesday. DeLuca founded the sandwich chain with his business partner, Dr. Peter Buck, in 1965 when he was only 17 years old.

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Under DeLuca's leadership, Subway began franchising in 1974 to grow into a chain with more than 44,000 locations worldwide. DeLuca was a major advocate for franchising throughout his life, telling Entrepreneur in 2005, "The franchisees are uniquely in touch at the local level. They see what's going on in their communities in a way we couldn't ever imagine."

DeLuca was diagnosed with leukemia in 2013. He continued to serve as CEO while receiving treatments, but named his sister Suzanne Greco president overseeing day-to-day operations in January of this year.

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