Patterns of spread of adenocarcinoma in the prostate as related to cancer volume

Peripheral zone (PZ) and transition zone (TZ) cancers of the prostate remain confined to their zone of origin under 4 cc volume, with progressive molding to TZ boundary. In PZ cancer, growth in perineural spaces over 4 cc volume directs cancer toward the base, around subcapsular nerve trunks, and often transcapsular. This tendency to stereotyped patterns of cancer spread in the prostate is investigated systematically here for the first time.

Cancers in 571 radical prostatectomy specimens were sorted by zone of origin and tumor volume. A traced map of each cancer at 3 mm transverse intervals was assessed for location, contour, selected linear measures and the "transverse (largest) reference plane".

Spread along prostate capsule characterized all but the smallest PZ cancers and was most extensive transversely. By 4 cc volume, most PZ cancers' transverse reference plane filled one side of PZ. Above 4 cc, bilateral spread, TZ invasion, and nodularity progressively increased, but dominant growth was toward the base along nerves to the superior pedicle; here capsule penetration was most common. TZ cancers arose mainly in anterior-mid TZ, invading anterior fibromuscular stroma (AFM) while small. AFM was massively invaded in many large tumors. Larger TZ cancers (> 4 cc) invaded anterolateral PZ but seldom penetrated posterior PZ.

Patterns and extent of spread of carcinoma in the prostate are stereotyped following a few principles regarding stromal interactions. Using these, sequential maps were presented of evolving prostate cancer contours at consecutive increasing volumes.