Is there treatment for mucinous adenocarcinoma of the prostate?

After 24 months of seeking a diagnosis and 2 TURP surgical procedures, I was finally diagnosed with a very rare prostate cancer: mucinous adenocarcinoma of the prostate. The surgeon said that there are only 30 cases in medical literature; I read that most urologists will never see a case of it. Is there a treatment for this? I asked: "How aggressive is it?" and was told, "We don't know." I asked: "Is it was localized?" Again, I was told "We don't know." I am 80 years old. Is this a prognosis of death? Or is there a treatment available?