McDonald’s Corp. CEO Charlie Bell, who was diagnosed with colorectal cancer in May, resigned Monday to focus on his battle with the disease, the company announced. The fast food giant named vice chairman Jim Skinner as its new CEO, and the board elected Mike Roberts, CEO of McDonald’s USA, to the position of president and chief operating officer.

“Charlie is a remarkable leader and well loved by the McDonald’s family, and we fully understand and respect his decision,” McDonald’s chairman Andrew J. McKenna said in a statement.

Bell, 44, was diagnosed with colon cancer soon after succeeding Jim Cantalupo in April after Cantalupo died of an apparent heart attack. Bell has missed significant time at work because of the cancer and earlier this month skipped a gathering of worldwide McDonald’s managers in his native Sydney, Australia.

Bell had returned to the hospital in September for further cancer therapy, and the Oak Brook, Ill.-based company has largely declined to comment on the severity of his condition or treatments.

Skinner has been with McDonald’s since joining the company in 1971 as a restaurant manager trainee and is a former head of its European business. In July, as part of a management shake-up designed to support Bell, he was given oversight of McDonald’s operations in Asia, the Middle East, Africa and Latin America.

“In Jim Skinner, McDonald’s has an outstanding leader who will continue the strategic focus established by Jim Cantalupo and Charlie Bell,” McKenna’s statement said.

Company spokesman Walt Riker said the company would have no additional comment Monday night.

Under Cantalupo and Bell, McDonald’s has staged a rebound in sales the past two years as the company slowed the pace of new store openings, added popular new salads and breakfast items to its menus and shed noncore parts of its business.

At McDonald’s, Bell rose through the ranks. He started working at a Sydney McDonald’s when he was 15 in 1975, becoming the youngest store manager in Australia by the age of 19.

One analyst said the change in leadership likely would have no major impact on the company’s stock because current McDonald’s executives are replacing Bell and the company has been doing well.

“Because this was an internal promotion, I think it’s basically status quo,” said Jerry McVety, president of McVety & Associates in Farmington Hills, Mich. “I don’t see any real philosophical changes.”