Toronto councillor and former mayor Rob Ford's doctors are "very concerned" about the reappearance and progression of his cancer, his chief of staff said Monday.

Doctors are still hoping Ford, who is receiving palliative treatment, can fight back and undergo further treatment, Dan Jacobs said in a statement released on behalf of the Ford family.

Jacobs also said Ford has not been transferred to any kind of palliative care unit, contrary to some media reports. Rather, Ford's palliative treatment, which includes sedation, began more than a year ago to alleviate pain and stress brought on by his cancer, Jacobs said.

Ford's condition has not changed since the family issued a statement Thursday that said Ford is continuing to fight cancer at Mount Sinai hospital "with his family beside him."

His release from hospital has not been discussed, Jacobs said earlier Monday, as the current goal is to get him healthy enough to receive another round of chemotherapy.

"Doctors have been clear since Councillor Ford's diagnosis that he is dealing with an extremely serious illness. We have not been given any indication of when he could possibly be discharged or a different treatment course be attempted, but they have also been clear that he still faces challenges," Jacobs said in a statement Monday evening.

As of Monday evening, more than 6,400 messages of support were posted on a get well website set up by the family.

Earlier this month, Doug Ford said his brother was pursuing targeted chemotherapy under the Panov program at Mount Sinai Hospital. 

The treatment involves implanting a piece of tissue from a patient's tumour into mice, which takes about three months to grow in the rodents. Researchers test different chemotherapy treatments on the mice to see which drugs are most effective in decreasing the size of the tumours. 

Ford, 46, was hospitalized last October for several days and it was later revealed he had a growth on his bladder. In November, his brother Doug confirmed Rob had two tumours on his bladder.

Ford underwent aggressive cancer surgery last year to remove an abdominal tumour after he was diagnosed with liposarcoma — a cancer that grows in fat cells. That initial diagnosis forced Ford to withdraw from Toronto's 2014 mayoral election campaign.