An analysis of 148 consecutive transition zone cancers: Clinical and histological characteristics

Purpose: To improve our understanding of transition zone cancer in terms of the diagnosis and biological behavior we examined all morphological and cl inical variables in 148 consecutive cases of untreated transition zone canc er after radical retropubic prostatectomy. We matched 79 cases by total can cer volume to 79 of pure peripheral zone cancer with no secondary tumors. Materials and Methods: Using the Stanford technique of prospective 3 mm. st ep sections we identified 175 of 996 men (18%) with untreated transition zo ne cancer after radical retropubic prostatectomy who had the largest cancer volume in the transition zone. We excluded 27 patients from study due to p revious transurethral prostatic resection or incomplete data. Preoperative serum prostate specific antigen (PSA) was determined by the Tosoh AIA-600 d agger PSA assay. Postoperatively a PSA of 0.07 ng./ml. and increasing repre sented biochemical failure when the assay was done in the ultrasensitive mo de. Results: Of the 148 cases of transition zone cancer 80% had organ confined disease, 70% stage T1c impalpable disease, 63% a positive initial prostatic biopsy, 62% unilateral cancer in the transition zone, 52% a secondary tumo r only in the peripheral zone, 61% serum PSA 10 ng./ml. or greater preopera tively, 36% cancer volume greater than 6 cc and 24% at least 50% Gleason gr ade 4/5 cancer. Only 20% of the tumors were located in the proximal third o f the transition zone near the bladder. The number of secondary tumors in t he transition zone ranged from 1 to 12 (median 3) and secondary tumor volum e ranged from 0.01 to 4.8 cc (median 0.6). Mean distance plus or minus stan dard deviation from the posterior prostatic capsule to the posterior border of the transition zone cancer was 12.0 +/- 7.6 mm. (median 12.3). While on ly 15% of patients had capsular penetration, 29% had anterior positive surg ical margins, 2.7% seminal vesicle invasion and 3.4% lymph node metastasis. When 79 transition zone cancers were matched by volume with 79 peripheral zone cancers, there were no differences in percent Gleason grade 4/5, serum PSA or prostate weight, although differences in clinical stage T1c to T2c and organ confined cancer were highly significant (p <0.0001). Kaplan-Meier curves showed that at 5 years of followup 49.2% of the men with peripheral zone cancer had undetectable PSA compared with 71.5% of those with transit ion zone cancer (log rank test p = 0.0002). Conclusions: Our report should make it easier to diagnose transition zone c ancer. The 72% biochemical PSA cure rate is significantly higher than the 4 9% cure rate for peripheral zone cancer. Since cancer volume and percent Gl eason grade 4/5 disease were the same in these 2 groups matched by cancer v olume, the differences in behavior of peripheral and transition zone cancer s must be sought at the molecular level unless anatomical location alone ex plains the differences in progression. Pathologists should differentiate tr ansition from peripheral zone cancer when analyzing radical prostatectomy s pecimens.