Former Toronto Mayor Rob Ford said Thursday that medical tests have shown that a new tumor doctors discovered on his bladder is cancerous.

He said he is "99 percent sure" the newly discovered tumor is "malignant," adding that he will undergo chemotherapy to treat the tumor.

Ford, appearing pained and at times in tears, told reporters outside of Toronto's Mount Sinai Hospital that he underwent testing after experiencing severe abdominal pain. He said the diagnosis caught him off guard.

"I'm not in fighting form now. Far from it," he said.

Ford previously underwent surgery to remove a cancerous tumor in his abdomen. He was diagnosed with malignant liposarcoma last year, forcing him to quit re-election bid for mayor. He ran for his old seat in city council instead and won.

Last month he said he was cancer-free.

"Now I'm just right back to square one so I have to start all over again," said an emotional Ford.

"I'm an optimist, but I'm a realist, too," he said. "If it's spread once, where else has it gone?"

However, Ford said he will continue to fight until the day he dies.

Ford's brother Doug said the former mayor will start the chemotherapy early next week after more tests and that the family has also considered surgery.

Ford gained international notoriety in 2013 when, after months of denials, he acknowledged he had smoked crack cocaine in one of his "drunken stupors," but he refused to resign.