TORONTO — Toronto Mayor Rob Ford will undergo 40 days of chemotherapy to treat a rare and difficult-to-beat cancer that forced him to do what months of scandals over drug and alcohol abuse could not — drop his bid for re-election.

Dr. Zane Cohen, a colorectal surgeon at Mount Sinai hospital, said Wednesday Ford has a malignant liposarcoma. Ford, who has been hospitalized for a week with a tumor in his abdomen, announced Friday that he was pulling out of the Oct. 27 race and his brother Doug would run in his place.

Cohen said the cancer is spreading and that they have found “a small nodule in the buttock” near the left hip. He said the mayor will be treated with fairly intensive chemotherapeutic agents within the next two days.