Prostate-specific antigen (PSA) testing has changed the face of prostate cancer, leading to earlier diagnosis and improved outcome, says David F. Paulson, md, professor and chairman, Division of Urology, Duke University Medical School.
Citing statistics from North Carolina, he said that before 1990, 90% of all prostate cancers were detected by digital rectal examination (DRE). In 1991, an increase in PSA-prompted biopsy began to be observed. By 1992, 65% of all new cases of prostate cancer were diagnosed as a result of PSA testing, and by 1993, that figure had risen to 90%.
In his presentation at a Lenox Hill Hospital program on prostate cancer, Dr. Paulson said that PSA-prompted diagnosis has resulted in a dramatic change in the presentation and outcome of the disease. "We are seeing more organ-confined and specimen-confined disease. PSA-driven diagnosis tends to shift patients into these two most favorable categories," resulting in earlier and more effective treatment.
Dr. Paulson favors using low PSA cut-offs to prompt biopsy, asserting that it will increase the population that is potentially curable. He suggests an abnormal DRE and a crude cut-off level of 4 ng/mL, rather than PSA density, as the indication for biopsy.
He cautions that high Gleason score disease will yield low PSA levels, since it decreases the ability of the gland to produce PSA. And he regards transurethral ultrasound as useful only to locate the prostate to obtain an adequate sampling for biopsy.
Dr. Paulson recommends prostate cancer screening for all men over 50, all black men over 40, and any man over 40 with a family history of the disease.
Residual Disease Dilemma
Although early detection improves the outcome of radical surgery, patients with residual disease still present a treatment dilemma. Dr. Paulson is unenthusiastic about postoperative androgen deprivation and adjunctive radiotherapy.
He explained that radiation drives PSA down, giving a 6-month to 2- or 3-year interval of apparent disease control, but in terms of long-term survival, radiation does not make a difference, he said. After PSA levels rise, it may be necessary to fall back on androgen deprivation therapy, if only to please the patient, he noted.
In Dr. Paulson's view, if it cannot be established that the patient is margin-positive and if PSA is undetectable postoperatively, there is no loss of survival advantage in delaying radiation until the PSA level becomes elevated. Even then, it should be undertaken only if the patient wants it.
He regards both small volume node-positive and margin-positive patients as destined eventually to do poorly. Even though there is little that can be done to improve survival in these cases, he recommends node dissection with radical prostatectomy,rather than node dissection alone.