Peripheral zone prostate cancers: location and intraprostatic patterns of spread at histopathology.

BACKGROUND

To describe the precise location of peripheral zone (PZ) prostate cancers at various stages of development and to demonstrate their pattern of intraprostatic spread from their site of origin.

METHODS

PZ cancers defined as cancers located in peripheral zone (PZ) including the anterolateral part of PZ, were identified from radical prostatectomy specimens. PZ cancers morphometric histopathological study included largest surface area, volume and spatial distribution.

RESULTS

Out of 188 PZ cancers, 179 were <4 cm(3) and 168 <2 cm(3). PZ cancers were still confined to their zone of origin for volumes <2 cm(3). Between 2 and 4 cm(3), some cancers partially spread into the transition zone or anterior fibromuscular stroma. Sixty-four and 90% of PZ cancers <4 cm(3) were located in the lower and posterior half of the gland respectively. Ten percent were located in the anterior horn of PZ. Overall, non-index (second) cancers were located in the ipsi and contolateral side of the index cancer (largest) in 31% and 69% of cases, respectively. Cancers <2 cm(3) were confined to one lobe in 164 of 168 (98%) cases and not confined in 3 out of 11 (27%) cancers 2-4 cm(3). On vertical axis, only cancers >or=2 cm(3) involved both apex and base.

CONCLUSIONS

PZ cancers contours and locations are predictable and conform to histological zone boundaries if <2 cm(3) in volume. Knowledge of PZ cancers origin and pattern of spread in PZ are of importance for imaging diagnosis, guidance for biopsy and focal therapy.