The study, scheduled to be published in the Jan. 1 issue of the journal Cancer and available online, found more than one-third of men with early prostate cancer received therapies that were not appropriate because of pre-existing conditions. The researchers theorize patients may be more open to describe sensitive topics on a questionnaire than in a conversation.

"Prostate cancer patients experience the same fears and hard decisions as all cancer patients do, but prostate cancer treatment directly affects very personal things that most people aren't comfortable talking about -- urinary, bowel and sexual function," study leader Dr. James Talcott of the Massachusetts General Hospital Cancer Center said in a statement. "In this case, however, having that information matters because the three major treatments -- prostate removal, external radiation and radiation seeds -- have different patterns of potential side effects. Knowing if patients already have problems in these areas should help guide treatment decisions."

Of the more than 400 patients who completed the study, 89 percent reported a pre-existing urinary, bowel or sexual problem on a questionnaire.