Anterior prostate cancer: is it more difficult to diagnose?

OBJECTIVE; To determine whether anterior prostatic tumours are adequately sampled using the Stamey sextant protocol, as a fifth of prostate cancers are anterior in distribution at radical prostatectomy.

All tumours (62) with an anterior distribution (>or=75% of the tumour anterior to the urethra) on radical prostatectomy whole-mounts, and in which the number and results of the sextant biopsies were available, were extracted from a prostate cancer database. Sixty-one posterior tumours (>or=75% of the malignant tissue posterior to the urethra) and their corresponding sextant biopsies were also retrieved for comparison. The number of biopsy sessions, the number of cores involved and the summated tumour length were recorded, together with the prostate gland weight, the tumour volume and the site of >or=75% of tumour in the superior-inferior axis.

Anterior tumours required significantly more biopsy sessions to diagnose prostate cancer than posterior neoplasms (anterior, one set 47; > one set 15; posterior, one set 57; > one set, four, P=0.007). Anterior tumours had fewer cores with tumour involvement and less summated tumour length than had posterior cancers. The mean (sd) number of positive cores was; anterior 1.8 (1.01), posterior 2.50 (1.30) (P=0.001); the summated tumour length was; anterior 5.05 (4.10) mm, posterior 9.25 (7.80) mm (P<0.001). There was no significant difference in gland weight (mean anterior 43.8 g; posterior 48.3 g, P=0.3) or tumour volume (mean anterior 1.85 mL; posterior 1.49 mL, P=0.11) between the groups. There was no significant difference between the incidence of anterior and posterior neoplasms with respect to their position in the superior-inferior axis (P=0.96).

Anterior prostate tumours account for 21% of all prostate cancers. They more often require multiple sets of sextant biopsies for diagnosis, and yield smaller areas of cancer on core biopsies than do posterior tumours in glands of similar weight and tumour volume. If prostate cancer is suspected clinically but biopsies are negative, targeting the anterior gland at subsequent prostatic biopsy should be considered.