To dream that you have cancer signifies a sense of despair, sadness, and pity. You also have an inability to exonerate or condone. You believe that you are throwing your life away one minute at a time. This dream also suggests there are aspects about your life that you are happy with, that are causing you grief, or are in some other way creating emotional pain.
To dream that someone else has cancer suggests that you should consider altering your antipathetic demeanor or manner of thinking before it becomes a cancer within your own life. Become more optimistic.