Toronto Mayor Rob Ford has a rare and "difficult" form of cancer in his abdomen — a malignant liposarcoma, his doctor said Wednesday. Dr. Zane Cohen told reporters that Ford will undergo three days of chemotherapy in the hospital and then have another round after an 18-day break. Depending on whether the drugs shrink the tumor, he may have more chemotherapy, Cohen said. "We are optimistic about this tumor," Cohen said, adding that the malignancy had spread to his buttock.

Liposarcomas account for 1 percent of cancers and grow in soft tissue like fat, blood vessels and muscles — not organs, the doctor said. "We think it's a fairly aggressive tumor," Cohen said. He said Ford was treated for kidney stones three years ago and no tumor was detected at that time. It was discovered when Ford went to the hospital complaining about abdominal pain.

Ford — who decided to run for re-election even after admitting he smoked crack — dropped out of the mayor's race a few days after going into the hospital, tapping his younger brother Doug as his replacement. He is running for a Council seal in his home district after his nephew stepped aside.

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My hopes are with @TOMayorFord, Renata and family. Cancer can be beaten and I know how important support is. He has mine. — Olivia Chow (@oliviachow) September 17, 2014

— Tracy Connor