Is the percentage of cancer in biopsy cores predictive of extracapsular disease in T1-T2 prostate carcinoma?

BACKGROUND

Information regarding the quantity of biopsy material invaded by cancer may supplement the usual criteria for the preoperative staging of patients suffering from clinically localized prostate carcinoma (T1-T2). However, conflicting conclusions have been drawn and this topic needs further investigation.

METHODS

A total of 170 patients had radical prostatectomy for T1-T2 prostate carcinoma. Patients' mean age (+/- standard deviation [SD]) was 66.05 +/- 6.12 years and mean prostate specific antigen (PSA) level (+/- SD) was 22.5 +/- 21.4 ng/mL (Yang Proscheck). Of the patients, 110 underwent transrectal ultrasound-guided biopsy with removal of 6 cores, from whom we had the percentage of biopsy, material invaded by cancer, the Gleason score, and the preoperative PSA. These parameters were compared with the pathologic features of the surgical specimen (capsule penetration, surgical margins, and Gleason score) and biologic progression (defined as persistent/recurrent postoperative PSA > 0.1 ng/mL).

RESULTS

The most valid threshold of biopsy material invaded by cancer for predicting surgical margins and capsule status, as well as biologic progression, was 10%. When < 10% of biopsy material was invaded by cancer, positive surgical margins (SM+) were present in 30.3%, capsular penetration (pT3, pathologic extracapsular involvement) in 27.3%, and biologic progression (P+) in 21.7%. The Gleason score did not improve this prognostic evaluation. The mean quantities of tissue invaded by cancer differed significantly between positive and negative surgical margin groups, between pT2 and pT3 groups, and between P- and P+ groups (no biologic progression/biologic progression). There was statistical significance (log rank test, P = 0.0320 in the survival without biologic postoperative progression between patients with < or = or > 10% of one core biopsy invaded by tumor. If < or = 10% of tissue in only 1 of 6 cores of a biopsy was invaded by tumor, the status was pT2, SM-, and P- in 87.5% of the patients.

CONCLUSIONS

On an individual basis, the percent of tissue containing carcinoma in core biopsies was a factor that lacked the statistical power to predict the status of the capsule and surgical margins, and the biologic progression. The finding of < or = 10% of carcinoma in 1 of 6 cores of a biopsy was correlated with a good prognosis.