Lectin and serum-PSA interaction as a screening test for prostate cancer.

The present investigation was designed to distinguish prostate cancer and benign prostate hyperplasia by lectin-prostate specific antigen (PSA) binding. The quantitative precipitin method of concanavalin A (Con A)-carbohydrate interaction was explored with the serum PSA of patients suffering from prostatic complications. The carbohydrate content in the precipitate after binding of Con A with serum PSA of prostate cancer was significantly lower than that of benign prostate hyperplasia. This may be due to altered sugar chain structure or less glycosylation of PSA in prostate cancer. We conclude that a serum value <3.0 microg/ml of the carbohydrate content of Con A-PSA precipitate indicates strong suspicion for prostate cancer and this cut off level is effective in reducing the rate of unnecessary biopsies in men with total PSA value between 4.0 to 10.0 ng/ml.