Any cancer is a dangerous and risky undertaking. It requires treatment usually. Generally speaking, the cancer that is malignant should be of the most concern because that type of cancer spreads. You do not want cancer to spread. That makes it more difficult to control. Benign cancer, on the other hand, does not spread and it is not as serious. As far as the location of the cancer, there are some cancers that are more difficult because they are harder to treat if a tumor infects that area.
For example, brain cancer and cancer of the liver seems to be very dangerous and have a greater risk than some of the other types of cancer. The cancers that can be easily treated may not concern some people.