According to a recent presentation by Mitchell C. Benson, MD*, at the 32nd Winter Urologic Forum – State-of-the-Art in Urology – January 25-29, 2008 – Vail, Colorado, USA most men who have failed a local, primary therapy and then experience a rising PSA will find that their follow-up therapy will most probably consist of anti-androgen hormonal therapy (ADT). As we all know the timing of the commencement of the ADT and how to utilize it (continuous or intermittent) remains very controversial.

PSA doubling time can be used to determine when, and in some cases if, androgen deprivation therapy should be prescribed. The Table below illustrates the utility of PSA Doubling time.

PSA Doubling Time………..Time to Metastases……………………Survival
……(Months)………………………..(Years)…………………………………(Years)
………..3…………………………………2…………………………………………….6
………..6…………………………………4…………………………………………….8
………..9…………………………………6…………………………………………….10
……….12…………………………………8……………………………………………12
……….24…………………………………12………………………………………….18

Depending upon your age, if your PSA doubling times are longer than 12-24 months you might wish considering not having any further therapy.

The belief of many oncologists is that the lower a man’s serum PSA following reaching castration levels correlates with the durability of the response. Maha Hussain et al., ASCO 2007 Abst # 4517 utilizing data from SWOG study 9346 comparing intermittent to continuous androgen deprivation in patients with newly diagnosed metastatic prostate cancer demonstrated that the median survival of a man whose PSA nadir level was < 0.2 ng/ml following castration was 75 months as compared to 44 months if the PSA was >0.2 and < 4.0 ng/ml and only 13 months if the PSA nadir was > 4.0 ng/ml.

If your PSA is >0.2 following achieving castrate level, you should sit down with your oncologist and discuss more aggressive therapy prior to becoming hormone refractory.

PSA levels also correlated with survival in men with hormone refractory prostate cancer being treated with docetaxel (chemotherapy). In an analysis of the data form SWOG 9916, Petrylak et al. N Engl J Med 2004; 351:1513-1520 demonstrated that if your serum PSA decreased by 50%, your median survival was 21 months whether treated by docetaxel and prednisone or mitoxantrone and prednisone. If your PSA did not decrease by 50 %, median survival was 15 months in the former group and 14 months in the latter.

Thus, your PSA nadir is valuable in predicting your potential survival whether or not you are hormone dependent and hormone refractory.

When you read this post you should remember that predicted survival times are medium (average) numbers. As an example when we say the medium survival is 20 months we mean the “average” is 20 months. Some men could have a survival time of 30 months while others only 10 months. There is no way of knowing where on the curve you might appear.

Joel T. Nowak MA, MSW

*George F. Cahill Professor and Chair Urology
Columbia University Medical Center
New York, New York U.S.A.