Posted 7/19/2009 12:56 PM (GMT -6)
I know we pooh-pooh the ultra-sensitive PSA test because its fluctuations are mostly meaningless. But I'm seeing some articles that point to a sort-of consensus that one use of those numbers may be approaching respectability.
Several studies have reached the conclusion that a post-RP nadir (lowest number reached) PSA of <0.01 is predictive of very low odds of recurrence. For example,
"Relapse rates in men with a PSA nadir of less than 0.01 (423), 0.01 (75), 0.02 (19) and 0.04 or greater ng/ml (28) were 4%, 12%, 16% and 89%, respectively. Men with a nadir of less than 0.01 ng/ml had a significantly lower relapse rate than men with a nadir of 0.01 (p <0.01), 0.02 (p <0.025) or 0.04 or greater ng/ml (p <0.01)." (J Urol. 2005 Mar;173(3):777-80.)
"Out of the 73 patients who have reached an undetectable nadir [<0.01], only 2 have failed (3%); this compares with 47 relapses out of the 61 patients (76%) who did not reach undetectable levels." (British Journal of Cancer (2000) 83, 1432–1436.)
"Based on the nadir PSA value, we divided 127 patients into three groups as follows: group A (n = 99): le0.01 ng/ml; group B (n = 16): 0.01-0.05 ng/ml, and group C (n = 12): ge0.05 ng/ml. ... During the observation period (median 31 months, range 6-75 months), biochemical recurrence occurred in 16 patients, that is, 1 in group A (6.3%), 4 in group B (25.0%), and 11 in group C (91.7%).... Conclusion: These findings suggest that the nadir serum PSA value measured by an ultrasensitive assay could be a useful predictor of biochemical recurrence after radical prostatectomy for clinically localized prostate cancer, and that careful follow-up should be considered in cases demonstrating a nadir PSA value >0.01 ng/ml because of the significantly higher probability of biochemical recurrence in such cases." (Urol Int 2006;76:227-231)
Yes, all are small studies. The results, as they say on Wall Street, are "interesting if true."