Toronto: Toronto Mayor Rob Ford has a very rare and aggressive type of cancerous tumour in his abdomen, his doctor said on Wednesday, and the controversial municipal leader will start chemotherapy treatment within days.

Ford, who made international headlines with his admission that he smoked crack cocaine while in office, was hospitalised last week after having unbearable abdominal pains. He dropped out of the city’s hotly contested mayoral race last week.

In a briefing on Wednesday, Toronto doctor Zane Cohen said the mayor had malignant liposarcoma, a type of cancerous tumour that arises in fat cells in deep soft tissue.

Cohen, a colorectal surgeon Toronto’s Mount Sinai Hospital, called it a “very rare” and “very difficult” type of tumour, noting that malignant liposarcoma makes up just 1 per cent of all cancers. However, he was also optimistic about Ford’s treatment prospects.

“The plan will be, initially, chemotherapy,” said Cohen.

“There may or may not be radiation involved, there may or there may not be surgery involved, it will all depend on the response to the initial treatment, and subsequent treatments as well.” Cohen said the mayor would start in on the first of two rounds of chemotherapy within 48 hours, followed by further testing in roughly 40 days to assess the tumour’s response to the treatment.

The doctor said the tumour, which measures about 4-3/4 inches by 4-3/4 inches (12cm by 12cm), was “very aggressive” and had likely been present for two or three years.

After being admitted to the hospital last week, Ford dropped his bid for re-election as mayor and was replaced by his brother and campaign manager Doug Ford. The mayor will instead run for a safe city council seat.

Doug Ford called the cancer diagnosis “devastating” in a statement on Wednesday, but said his brother remained “upbeat and determined to fight.” ‘NOT GOOD’ Mayor Ford has had his own health struggles, having had part of his colon removed and kidney stones in separate incidents in the past. He also sought to lose weight but struggled to get below 310 pounds (141kg).

In May and June, the mayor underwent rehab for drug and alcohol abuse. He emerged noticeably thinner though still obese.

Ford’s doctor would not comment on the prognosis on Wednesday, saying only that the specific type of sarcoma the mayor has is “sensitive” to chemotherapy.

Dr Mitchell Posner, chief of general surgery and surgical oncology at the University of Chicago Medicine, who is not treating Ford, said the prognosis of this type of cancer is generally determined by the size and grade of the tumour.

In general, he said, such tumours are best treated by removing them surgically. “Some of them can be removed and never come back,” Posner said.

While doctors found the tumour last week, they did not reveal it was cancer until Wednesday.

Ford, who came to power in 2010 pledging to cut waste at city hall and keep a lid on taxes, said in an interview in the Toronto Sun newspaper on Saturday that he was “shocked” and “devastated,” and had to quit the race to focus on his health.

“It’s not good,” Ford was quoted as saying about his preliminary diagnosis. “I guess the good Lord wants me somewhere else.”