The doctor in charge of Rob Ford’s medical team announced Wednesday that the tumour in Ford’s abdomen is malignant. According to Dr. Zane Cohen, the tumour is part of a malignant liposarcoma, a cancer that forms in fat cells.

Cohen said he’s optimistic about Ford’s recovery.

“It’s fairly aggressive,” Cohen told press, “but we are treating this very aggressively in order to eradicate the tumour.”

Cohen said the tumour is four by four inches and is responding well to chemo.

Ford will start the first of two rounds of chemotherapy within 48 hours. Chemo will last for three days, after which Ford will be allowed to leave the hospital for 17 days and then be re-admitted.

Cohen said dead tissue within the tumour is what is causing the pain for Ford. A second tumour in Ford’s buttocks is part of the same cancer.

Pleomorphic liposarcoma is a very rare form of cancer, which has no known cause.