Role of percent positive biopsies and endorectal coil MRI in predicting prognosis in intermediate-risk prostate cancer patients.

PURPOSE

This study was performed to determine the clinical factors that can optimize preoperative staging for clinically localized intermediate-risk prostate cancer patients.

MATERIALS AND METHODS

Logistic and Cox regression multivariable analyses were performed on 480 prostate cancer patients whose disease was confined to the prostate to evaluate the ability of clinical stage, prostate-specific antigen (PSA), biopsy Gleason sum, percent positive biopsies, and endorectal coil magnetic resonance imaging (MRI) results to predict pathologic established extracapsular extension, seminal vesicle invasion, and time to postoperative PSA failure in patients with clinically localized prostate cancer. Intermediate risk was defined as PSA 4-10 ng/mL and Gleason sum 5-7; PSA 10-20 ng/mL and Gleason sum < or = 7.

RESULTS

Intermediate-risk patients with at least 50%, 67%, 83%, or 100% positive biopsies have disease pathologically confined to the prostate at least 45% of the time; however, if an endorectal coil MRI is positive for either capsular penetration or seminal vesicle invasion, no more than 29% of patients have pathologically determined organ-confined disease. No intermediate-risk patient with both a positive MRI and at least 50% positive biopsies had pathologically determined organ-confined disease. Intermediate-risk patients with less than 50% positive biopsies had pathologically determined organ-confined disease in at least 77% of the cases.

CONCLUSIONS

Intermediate-risk patients with an endorectal coil MRI showing extracapsular extension or seminal vesticle invasion are at high risk for early postoperative PSA failure. The concomitant presence of at least 50% positive biopsies increases this risk to unity. Therefore, these patients are not good candidates for surgery alone because of their high risk of extraprostatic disease and should be considered for entry onto phase III trials examining the effect of adding androgen-deprivation therapy to definitive local therapy (external-beam radiation therapy or surgery) on overall survival. The subgroup of intermediate-risk patients likely to benefit from an endorectal coil MRI are those patients with PSA > 10-20 ng/mL; biopsy Gleason score < or = 7, and at least 50% positive biopsies representing approximately 7.5% of the total patient population.