People with cancer are three times more likely than the general population to develop depression, and twice as likely as other hospitalized patients. The greater the pain, the more likely the depression. Cancer, or simply the thought of cancer, may cause stress, which might result in depression, but this is only a hypothesis. At any rate, cancer is difficult enough to struggle against without one being handicapped by depression, as well, and the combination can be fatal. The consequences of untreated depression can be severe.
Depressed patients are also more likely to commit suicide or request physician-assisted suicide.
Estimates of cancer patients who take their own lives range from twice the incidence of the general population to ten times. Ironically, owing to the intensely horrific nature of cancer, not to mention its treatment, it is not uncommon to dismiss a patient's depression or suicidal ideation as normal. As a result, many physicians do not look for depression, or assume that because depression is a normal reaction to cancer, it does not merit treatment. This is sort of like assuming that because bleeding is the result of being stabbed, the wound does not have to be stanched. By the same token, however, one should not be hasty in pointing a finger at depression.