Subway co-founder's sister named president as her brother is treated for leukemia

Suzanne Greco will take over as president of Subway as her brother, the co-founder of the sandwich chain, is treated for leukemia.

Greco will oversee day-to-day operations and report to her brother, Fred DeLuca, who will remain CEO.

Greco, 57, sits on Subway's board and has been involved with the company since it opened its first store in 1965.

The Milford, Connecticut, company is privately held and doesn't disclose its financial results. Last year, industry tracker Technomic said average sales for Subway stores in the U.S. declined 3 percent from the previous year.

Subway announced in 2013 that DeLuca was diagnosed with leukemia. The company said at the time that its senior management team was managing day-to-day operations, but that DeLuca was communicating regularly with them from Florida.