NEW YORK » Subway co-founder Fred DeLuca, who turned a sandwich shop he started as a teenager into the world’s largest fast-food chain, died Monday evening. He was 67.

DeLuca’s death came two years after Subway said he had been diagnosed with leukemia and was scaling back on his leadership role at the company. It also came just weeks after the 50th anniversary of Subway, which is known for its "Footlong" sandwiches and says it has more than 44,000 locations around the world.

The company traces its roots to 1965, when DeLuca opened a sandwich shop at the age of 17 to help pay for college. The idea came from a family friend, Peter Buck, who was co-founder and provided the $1,000 to start the business.

"I knew nothing about making sandwiches, nor the food industry," DeLuca later wrote in a book.

DeLuca and Buck opened their first store in Bridgeport, Connecticut under the name "Pete’s Super Submarines," with the priciest sub selling for 69 cents. The name was changed to the snappier "Subway" in 1968, and the pair decided to fuel growth by franchising, or letting others open Subway stores in exchange for fees.

By 1988, Subway had 2,000 locations. By 1990, it reached the 5,000-store mark. And by 1994, it had more than 8,000 locations.

Subway, based in Milford, Connecticut, is privately held and doesn’t publicly report its financial performance or executive pay packages. But this year, Forbes magazine pegged DeLuca’s net worth at $3.5 billion, making him the 259th-richest individual in the United States.

In July 2013, Subway announced that DeLuca had been diagnosed with leukemia. It said DeLuca was in regular contact with his management team, but on a reduced basis as he received treatment. Then earlier this summer, Subway said DeLuca’s younger sister, Suzanne Greco, would take over as president and oversee day-to-day operations. DeLuca remained CEO.

The company did not immediately say Tuesday if a successor had been named as CEO.

Subway has been facing some recent challenges in addition to DeLuca’s health. The company cut ties with longtime pitchman Jared Fogle this summer after Fogle agreed to plead guilty to allegations he paid for sex acts with minors and received child pornography.

In addition, some feel Subway has overextended itself with its more than 27,000 U.S. locations. Last year, average sales at established U.S. locations fell 3 percent, according to Technomic.

In DeLuca’s book "Start Small Finish Big: Fifteen Key Lessons to Start — and Run — Your Own Successful Business," DeLuca recalled living in public housing in the Bronx as a child. His father hadn’t graduated high school, but his mother had stressed the importance of education while growing up.

After he graduated high school, DeLuca had planned on becoming a doctor. That was why he started the sub shop with Buck — to support his college education.

"It wasn’t intended to support me forever," DeLuca wrote.

DeLuca is survived by his wife, son and sister, according to Subway, which announced his death Tuesday.