Toronto Mayor Rob Ford has been diagnosed with a rare type of cancer, his doctor said Wednesday. “It is a difficult and very rare type of tumour,” Dr. Zane Cohen said in a Wednesday evening press conference, describing Ford's cancer as a malignant liposarcoma. “It's a fairly aggressive tumour…but we are treating this aggressively in order to irradiate the tumour. We are optimistic about this tumour.” Dr. Cohen said he is “optimistic” that chemotherapy could be successful. There is a large tumour in his abdomen and a smaller one in his bu*tock, near his left hip, the surgeon said. Dr. Zane Cohen gives an update of Rob Ford's condition during a news conference at Mount Sinai Hospital in Toronto Wednesday. The abdomen tumour is about 12 by 12 centimetres (about 4 inches), larger than the width of a baseball. The other tumour is about two centimetres. Chemotherapy will begin within 48 hours. Doctors will decide the next step depending on how his tumour responds to treatment. There may be additional rounds of chemotherapy or surgery, Dr. Cohen said. Ford will receive three days of chemo d**, followed by 18 days off. He will then receive a second round of chemo. The mayor, now running for a council seat, will likely be able to work through treatment but will face “tough days,” the doctor said. Dr. Cohen is an expert colorectal surgeon and is leading Ford's medical team. Liposarcoma is a tumour that arises in fat cells in soft tissue such as muscle, fat or joint tissue. It makes up less than 1% of diagnosed adult cancers. The cause of the type of cancer is not known. Dr. Malcolm Moore, head of medical oncology and hematology at Princess Margaret Cancer Centre, said the mayor's type of cancer arises from fatty tissues, which is uncommon. “The treatment for sarcoma is quite different,” he told reporters. “It's sensitive to different d** and the surgical approach would be somewhat different.” Having said that, he noted there are newer treatments that focus on the genetic features of sarcoma. Numerous members of the Ford family visited Mount Sinai Hospital Wednesday, saying little to the media. In a statement, Councillor Doug Ford said he can't begin to share how devastating his brother's diagnosis is to the family. “He is an incredible person, husband, father, brother and son and he remains upbeat and determined to fight this,” Ford said. “Rob will beat this.” Mayor Ford was admitted to hospital last Wednesday after complaining of severe abdominal pain. On Thursday, doctors said a significant ma** was found in his abdomen. On Friday, Ford dropped out of the mayoral race and his brother announced he would run in his place. The one-term mayor then signed up to run for his old council seat in Ward 2. Ford's nephew, 21-year-old Michael Ford, pulled out of the race for Ward 2 and later registered to run for school trustee. Mayor Rob Ford's brother Doug Ford arrives at Mount Sinai Hospital in Toronto, Wednesday, Sept.17, 2014. Doctors are set to provide an update on Mayor Ford's health today, a full week after he was diagnosed with an abdominal tumour. Mayor Ford's father, Doug Ford Sr., died in 2006, mere months after he was diagnosed with colon cancer. A mayoral debate at 6 p.m. between John Tory and Olivia Chow was cancelled as both candidates wished Ford the best. “I wish Rob Ford and his wife, Renata, well,” Chow said in a joint press conference with Tory after the diagnosis was revealed. “I know what it's like when a family receives bad news. I hope he can win this battle.” Tory said said he hoped Torontonians would “take a moment for a prayer” for Ford. Deputy Mayor Norm Kelly said in a statement: “Like every challenges he takes on, I know he will fight until he wins.” Andray Domise, Ford's main opponent in the Ward 2 election, Tweeted: “I offer a prayer for Mayor Rob Ford's speedy recovery, and my sympathies to his family during this difficult time.”