Subway co-founder Fred DeLuca, who turned a sandwich shop he started as a teenager into the world’s largest fast-food chain, has died aged 67.

DeLuca’s death came two years after Subway said he had been diagnosed with leukaemia and was scaling back on his leadership role at the company.

It also came just weeks after the 50th anniversary of Subway, which 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 his education. 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.

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 does not 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 US.

In July 2013, Subway announced that DeLuca had been diagnosed with leukaemia. It said he 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 if a successor had been named as CEO.

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

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

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

He is survived by his wife, son and sister.