Erectile dysfunction is the inability to achieve and/or sustain an erection adequate for sexual intercourse. A concern for many men with a diagnosis of prostate cancer is whether or not they will still be as sexually functional as they were prior to having received treatment. It can be both physically and emotionally taxing to cope with.  It’s important to understand that prostate cancer is not the direct cause for erectile dysfunction, although certain treatments for the disease can directly cause the condition.