Carbohydrate antigen 19-9-positive prostatic ductal adenocarcinoma effectively treated with cisplatin and gemcitabine.

We performed a radical retropubic prostatectomy on a 59-year-old male patient who was diagnosed with prostatic carcinoma. Pathological findings revealed a ductal adenocarcinoma in the left lobe of the prostate, and a conventional well-differentiated adenocarcinoma in the right lobe. Immunohistochemistry revealed that CA19-9 was positive in the ductal adenocarcinoma, and prostate-specific antigen was positive in the conventional well-differentiated adenocarcinoma. Since there was an increase in the level of serum CA19-9, which had decreased postoperatively, along with the appearance of local recurrence and bone metastasis, we treated the patient with cisplatin and gemcitabine. As a result, the level of serum CA19-9 was normalized and a reduction of the metastatic focus was observed.