Which hospital unit are cancer patients placed in?

Depends on hospital: Some hospitals have specialized oncology wards, others may not. This usually depends on the size of the hospital, if its a teaching hospital, private vs public, etc. If a hospital does not have a specific oncology unit, cancer patients may be admitted to a general hospital bed.

Oncology Ward: Many hospitals have an oncology ward where all the patients with the diagnosis of cancer are admitted for specialised care. Some hospitals do not have such a special unit...So patients are scattered all over the hospital in regular rooms.