“First, errors in applying these criteria are surprisingly common, suggesting that a patient’s assigned clinical stage may not accurately portray his disease characteristics before prostate surgery,” first author Dr. Adam C. Reese noted in an e-mail to Reuters Health.
“Second, even after correction of these staging errors, clinical stage does not appear to be associated with prostate cancer recurrence after radical prostatectomy,” he said.
“These findings question the utility of our current staging system for localized prostate cancer,” said Dr. Reese, chief resident in the department of urology at University of California, San Francisco.
He and colleagues analyzed information on a large group of men with localized prostate cancer from the Cancer of the Prostate Strategic Urologic Research Endeavor, or CaPSURE, database. Correct stage was determined by digital rectal examination (DRE) and transrectal ultrasound (TRUS) findings and was compared with the clinical stage reported by the clinician.
Based on current staging criteria for localized prostate cancer from the American Joint Committee on Cancer (AJCC), 1,370 of 3,875 men (35.4%) were staged incorrectly, the researchers found.
Staging errors more often resulted in downstaging rather than upstaging of cancer (55.1% vs 44.9%). Patients with TRUS lesions were significantly more likely to be staged incorrectly than those with abnormal DRE findings (65.8% vs 38.2%).
Most of the staging errors appear to be due to “disregard for TRUS findings and inappropriate consideration of biopsy results when assigning clinical stage,” the clinicians report.
“We were not very surprised to find the frequency with which clinical stage is misassigned,” Dr. Reese told Reuters Health. “In our experience, many practitioners appear to incorporate biopsy results and ignore TRUS findings when assigning clinical stage assignment.”
TRUS abnormalities were disregarded in 65.8% of the cohort. And while it is “generally accepted” that biopsy results should not be incorporated into clinical stage assignment, biopsy laterality was “strongly” associated with clinical stage assignment in the current study, the investigators note.
Even when inaccuracies in clinical stage were corrected, a multivariate Cox regression model (using corrected clinical stage) did not identify an association between advanced clinical stage and risk of biochemical disease recurrence, the investigators report.
Other clinical variables, including increasing PSA level, advanced biopsy Gleason score, and percentage of positive biopsy cores greater than 33%, correlated strongly with increased risk of disease recurrence.
“These findings,” they say, “argue against the utility of a DRE-based and/or TRUS-based staging system for localized prostate cancer.”
Cancer, online November 22, 2010.