SAN ANTONIOSome prostate cancer patients may not require salvage radiation therapy (RT) following postprostatectomy PSA failure if they exhibited a low preoperative PSA velocity and have a persistent, nearly stable postoperative PSA level. Anthony V. D’Amico, MD, PhD, presented the findings at the 100th Annual Meeting of the American Urological Association (abstract 1678). Although PSA failure following radical prostatectomy can present a significant risk to the patient, certain PSA failures may not indicate a life-threatening situation. In these cases, subjecting patients to the toxicity associated with radiation therapy may be unnecessary. Dr. D’Amico, of the Dana-Farber Cancer Institute and Brigham and Women’s Hospital, Boston, and his colleagues investigated whether these patients with benign PSA failure could be identified based on diagnostic factors.
Dr. D’Amico and his colleagues, including William J. Catalona, MD, of Northwestern University, studied 1,011 men with localized prostate cancer and evaluated the ability of different factors to predict mortality, including 1-year PSA velocity prior to diagnosis, baseline PSA, Gleason score, and clinical tumor category. The investigators attempted to correlate these variables with postoperative PSA doubling time, and PSA doubling time with cancer-specific and overall mortality rates.
A short postoperative PSA doubling time, defined as less than 3 months, clearly predicted death due to cancer (P = .006) and all causes (P = .007). In turn, a short PSA doubling time occurred significantly more often in patients with a preoperative PSA velocity greater than 2.0 ng/mL/yr (P = .001) and a biopsy Gleason score of 7 (P = .007) or 8 to 10 (P = .003). This correlation indicates a higher mortality risk for these patients.
Conversely, certain characteristics were associated with a postoperative PSA doubling time of at least 12 months or no PSA failure (postoperative PSA concentration of 0.2 ng/mL or less). These baseline parameters included a PSA level of less than 10 ng/mL (P = .005), a nonpalpable tumor (P =.0006), Gleason score of 6 or less (P < .0001), and a preoperative PSA velocity of 0.5 mg/mL/yr or less (P = .029).
A total of 4% of the cohort (n = 40) exhibited these favorable baseline characteristics and had a very long postoperative PSA doubling time of 12 months or more. These patients exhibited favorable prostatectomy T category, Gleason score, and margin status that were not significantly different from those of the subset of patients with similar baseline characteristics who did not experience PSA failure.
While PSA levels persisted above 0.2 ng/mL in 31 of these 40 patients, after a median follow-up of 3.6 years, 24 of these 31 patients had PSA levels that remained stable at 0.25 ng/mL or less (a total of 77% of those with persistent detectable PSA). Dr. Catalona explained, "In these patients with protracted PSA rise, we may be able to go years without additional therapy; however, if the doubling time did begin to shorten, we could then institute adjuvant therapy."