Capsular Penetration in Prostate Cancer. Significance for Natural History and Treatment

We established the location and extent of complete capsule penetration by prostate cancer in 176 radical prostatectomy specimens and related these findings to cancer volume, location of positive surgical margins, and presence of nodal metastases or seminal vesicle (SV) invasion. Extent of capsule penetration, cancer volume, and positive nodes/SV were strongly intercorrelated. It could not be shown that capsule penetration was related to prognosis independently of its correlation with cancer volume. Twelve cubic centimeters was a critical cancer volume; above that, combinations of extensive capsule penetration, positive surgical margins, and positive nodes/SV were almost universal. In cancers under 12 cc, positive surgical margins were only moderately correlated with cancer volume; they often represented surgical resection into the capsule rather than a complication of capsule penetration by tumor and were most common at the apex, where dissection is most difficult. In non-transition zone cancers (148 cases), capsule penetration was most common posterolaterally, where nerves penetrate the capsule. In transition zone cancers (28 cases), capsule penetration was much less common and was located more anteriorly. Apical positive margins were also relatively common in transition zone cancers, but seminal vesicle invasion was never seen.