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A model for the number of cores per prostate biopsy based on patient age and prostate gland volume
A R Vashi1, K J Wojno, B Gillespie
1Section of Urology, University of Michigan, Ann Arbor 48019, USA.
Purpose:
The systematic sextant biopsy is currently the gold standard for the tissue diagnosis of prostate cancer. However, it is unknown whether this 6 core approach provides optimal sampling of all prostate glands in men of all ages. The goal of the current study was to determine the appropriate number of cores per prostate biopsy based on patient age and prostate gland volume.
Materials And Methods:
Patient age and tumor volume doubling time were used to calculate life threatening, clinically significant tumor volumes at diagnosis for 5-year intervals of patient age. A mathematical model was created to determine the minimum number of cores necessary to identify these life threatening tumor volumes in prostate glands 10 to 80 cm.3 without detecting clinically insignificant cancers.
Results:
Younger men and men with larger prostate glands require more than 6 cores to ensure the diagnosis of life threatening prostate cancer. These prostates are currently under sampled by sextant biopsy. In a select group of older men who require fewer than 6 cores sextant biopsy may over sample these prostates and lead to over treatment.
Conclusions:
The standard sextant biopsy provides optimal sampling of only a minority of prostate glands. An approach to prostate biopsy based on patient age and prostate gland volume maximizes the detection of clinically significant prostate cancer.