When planning for treatment, radiation oncologists evaluate the pretreatment PSA (prostate specific antigen) because it is a strong predictor of the patient's outcome following radiotherapy. The pretreatment PSA is used to determine the appropriate radiotherapy dose and whether androgen deprivation therapy should be given. Doctors say evaluating a patient's PSA level after surgical removal of some prostate tissue with a TURP, which is often done for men who have an enlarged prostate with significant urinary symptoms unrelated to prostate cancer, is not an accurate picture of disease progression.
"PSA is secreted from both normal and cancerous tissue," explained lead author David J. D'Ambrosio, M.D., a resident in the radiation oncology department at Fox Chase Cancer Center. "Patients who have had a TURP prior to their prostate cancer treatment may have lower pretreatment PSA levels because there is less prostate tissue remaining. This can mislead physicians regarding the extent of disease." D'Ambrosio said that men with a PSA level of 10 to 20 likely would have had a PSA of greater than 20 if they did not have surgery to remove their some of their prostate, and therefore would have received more aggressive treatment.
The Fox Chase study evaluated 1,287 men with low to intermediate risk with a similar stage of disease. All had a pretreatment PSA of less than 20 and received 3D conformal radiotherapy without hormone (androgen deprivation) therapy. Of these, 143 men had a prior TURP. The median pretreatment PSA was 7.3 (range: 0.1-19.9). The number of men with PSA greater than 10 was 362 (28 percent).
Prior TURP was the common denominator among patients who had a pretreatment PSA of 10 to 19.9 who later recurred. There was no strong relationship between the surgery and recurrence for patients with a pretreatment PSA of less than 10.
As D'Ambrosio explained, "Patients with a pretreatment PSA of 10 to 19.9 were more likely to recur if they had prior TURP. This group also had other pretreatment indicators that normally would not have indicated a high-risk of recurrence." (Gleason Score of 2-6 vs. 7, Stage T1c vs. T2).
"A history of a TURP reduced the accuracy of PSA as a pretreatment indicator for recurrence. The treatment plan for men who have an intermediate PSA who have also had TURP may include a recommendation of androgen deprivation."
Other study authors include Fox Chase radiation oncologists Mark Buyyounouski, M.D., Eric M. Horwitz, M.D., Steven J. Feigenberg, M.D., Alan Pollack, M.D., Ph.D., and biostatistician Karen Ruth.
Fox Chase Cancer Center was founded in 1904 in Philadelphia as the nation's first cancer hospital. In 1974, Fox Chase became one of the first institutions designated as a National Cancer Institute Comprehensive Cancer Center. Fox Chase conducts basic, clinical, population and translational research; programs of prevention, detection and treatment of cancer; and community outreach. For more information about Fox Chase activities, visit the Center's web site at www.fccc.edu or call 1-888-FOX CHASE.