Pathological parameters of radical prostatectomy for clinical stages T1c versus T2 prostate adenocarcinoma: decreased pathological stage and increased detection of transition zone tumors

Abstract

Purpose: Studies of radical prostatectomy specimens have suggested that the majority of prostate specific antigen detected (clinical stage T1c) tumors are clinically significant. We compared tumor location and pathological parameters in the radical prostatectomy specimens of stages T1c versus T2 cases in a 3-year period. The percent of stage T1c disease represented a stable majority of patients undergoing treatment for clinically localized prostate cancer.

Materials and methods: From January 1, 1998 to December 31, 2000, 417 radical prostatectomies were performed at Vanderbilt University, including 246 for stage T1c and 108 for stage T2 disease. A total of 37 patients were excluded from study because of neoadjuvant antiandrogen treatment. Pathological parameters, including tumor location in the transition and/or peripheral zone, tumor Gleason grade, tumor stage, total tumor volume and surgical margins were compared in stages T1c and T2 cases, and in transition versus peripheral zone stage T1c tumors in completely embedded whole mount specimens.

Results: In contrast to stage T2 lesions, stage T1c tumors were of significantly lower Gleason score with a higher percent of Gleason score 5 and lower percent of Gleason score 6, 7 and 8 or greater. They also had a significantly smaller volume and lower pathological stage. Of stage T1c tumors 77% were organ confined versus 62% of stage T2 tumors. There was no statistically significant increase in clinically insignificant neoplasms in stages T1c versus T2 cases (13% versus 7%) when using a volume criterion of less than 0.2 cc but a statistically significant increase in clinically insignificant disease was observed using a volume criterion of less than 0.5 cc (22% versus 9%). Whereas none of the T2 tumors were located in the transition zone and 17% were located in the transition and peripheral zones, 14% of stage T1c lesions were exclusively in the transition zone, with another 17% in the transition and peripheral zones. Compared with peripheral zone tumors transition zone stage T1c tumors had a lower Gleason score with an increase in Gleason score 5 and lower percent of Gleason score 6, 7 and 8 or greater. Although transition zone stage T1c lesions were significantly larger than peripheral zone stage T1c lesions, they had a lower pathological stage with 94% versus 72% organ confined.

Conclusions: Prostate specific antigen detected stage T1c tumors had a lower grade, stage and volume than stage T2 tumors during the same period. Lower tumor grade in stage T1c cases is due at least in part to the increased detection of Gleason pattern 2 containing transition zone tumors. Despite the larger size, T1c transition zone tumors appear to be more favorable with higher rates of organ confined and lower grade tumors. If such transition zone tumors prove to be biologically distinct, improved strategies to identify these lesions preoperatively may result in more conservative treatment recommendations.