Objectives: To evaluate the effect of the tumour-positive biopsy site at extended biopsy on tumour volume and potential biological significance of prostate cancer.
Patients and methods: We retrospectively evaluated radical prostatectomy specimens from 247 consecutive men diagnosed with prostate cancer by extended biopsy. Men who had both a positive sextant and alternative site were excluded, resulting in 132 evaluable men. We assessed age, pretreatment prostate-specific antigen (PSA) level, prostate volume, pathological stage, Gleason score, total tumour volume, and location (sextant or alternative site) of the positive biopsy. Patients were grouped by location of the positive biopsy, i.e. sextant site only or alternative site only, including anterior horn, midline region and transition zone.
Results: A biopsy from a sextant-only or an alternative site only was positive in 42% (56/132) and 58% (76/132) of men, respectively. There was no significant difference in PSA level, number of positive cores, pathological stage, Gleason score, total tumour volume or the incidence of low-volume/low-grade cancer (volume <0.5 mL and a Gleason score of </=6) between the groups. In men with one positive core, there was no significant difference in total tumour volume (median 0.20 vs 0.36 mL, respectively) or in the incidence of low-volume/low-grade cancer (42% vs 40%, respectively) between the groups.
Conclusions: Total tumour volume and the incidence of low-volume/low-grade cancer detected at an alternative site only were comparable to those of cancers detected at a sextant site only. Alternative site biopsy did not increase the incidence of low-volume/low-grade cancers detected.