PROSTATE CARCINOMA PATIENTS UPSTAGED BY IMAGING AND TREATED WITH IRRADIATION - AN OUTCOME-BASED ANALYSIS

BACKGROUND. The American Joint Committee on Cancer (AJCC) staging of p rostate cancer relies upon digital rectal examination (DRE) findings, but suggests using all available information, including prostate imagi ng studies, prior to definitive treatment of prostate carcinoma. We ha ve studied whether patients upstaged by imaging have a different outco me after treatment with external beam radiation therapy (RT) from thos e not upstaged. METHODS. The records of 499 men with clinically locali zed adenocarcinoma of the prostate treated only with definitive extern al beam irradiation from January 1986 to December 1993 were reviewed. The 348 patients with any one or a combination of the following pretre atment imaging studies were considered eligible; transrectal ultrasoun d (TRUS), pelvic MRI, or endorectal MRI. Patients were assigned two cl inical stages: one based upon palpation criteria alone (palpation stag e) and the other allowing for any upstaging by imaging abnormalities ( AJCC or imaging stage). The Kaplan-Meier method was used to estimate b iochemical no evidence of disease (bNED) survival where a failure was defined as a prostate specific antigen (PSA) greater than 1.5 and incr easing. Differences in outcome were evaluated by the log-rank test. RE SULTS. Overall upstaging by TRUS or MRI to any higher stage occurred i n 115 of 312 palpation T1c-T2c patients (37%). These upstaged patients had an unexpected improvement in bNED survival (84% vs. 71%, P = 0.05 ) compared with those who were not upstaged due to the upstaged patien ts having a significantly greater number with a pretreatment PSA < 10 ng/mL. T1c patients were upstaged by imaging in 81% of the 94 patients . The 36-month bNED survival of palpation T1c and imaging T2 patients was similar (88% vs. 88%, P = NS), but both were significantly improve d compared with the 36-month bNED survival for palpation T2 patients ( 88% vs. 71%, P = 0.04). There was no significant difference in 36-mont h bNED survival for imaging T2c (bilobar disease) patients compared wi th their original palpation stage disease. Upstaging to T3 occurred in 10% of palpation T1c-T2c patients. There was no difference in 36-mont h bNED survival for the imaging T3 patients compared with their origin al palption stage (84% vs. 71%, respectively, P = 0.04). There was a s ignificant improvement in the 36-month bNED survival for imaging T3 pa tients compared with palpation T3 patients (84% vs. 50% respectively, P = 0.01). Multivariate analysis demonstrated palpation stage to be a significant predictor of bNED survival (P = 0.001), while AJCC stage ( including imaging) is not predictive. CONCLUSIONS. Using the endpoint of bNED survival, upstaging by TRUS/MRI does not separate prostate can cer patients treated with RT into groups with different prognoses. Upo n multivariate analysis, palpation stage alone, not AJCC stage includi ng imaging upstaging, is a significant predictor of bNED survival. (C) 1996 American Cancer Society.