Extended biopsy based criteria incorporating cumulative cancer length for predicting clinically insignificant prostate cancer

Abstract

What's known on the subject? and What does the study add? The criteria used for selecting patients with prostate cancer for active surveillance (AS) are still not satisfactory due to the difficulty in predicting the significance of the prostate cancer. Urologists could predict insignificant prostate cancer by incorporating cumulative cancer length and biopsy Gleason score, derived from extended biopsy. The present study has added new criteria for predicting insignificant prostate cancer, which would lead to a better selection of candidates for AS.

Objective: • To develop extended biopsy based criteria for predicting insignificant cancer (IC) using extended biopsy findings.

Patients and methods: • From 2000 to 2009, 1575 patients with prostate cancer were primarily treated by radical prostatectomy in two referral hospitals. • Of these, the study cohort comprised 499 patients with extended biopsy confirmed, clinically organ-confined (cT1-2N0M0) prostate cancer with PSA levels of <20 ng/mL. • Cancer information obtained through extended biopsy included cumulative cancer length (CCL) divided by the number of biopsy cores (CCL/core).

Results: • Pathological examination revealed 39 ICs (7.8%). All these ICs fell in a category of prostate cancer with clinical stage ≤ T2a and 2005 International Society of Urological Pathology Consensus Conference (ISUP) modified biopsy Gleason score ≤ 7. • Accordingly, we analysed predictors of IC in a subset cohort of 370 patients in this category. A multivariate logistic regression analysis revealed that 2005 ISUP modified biopsy Gleason score and CCL/core were independently significant predictors of IC. • We determined a threshold value of CCL/core of 0.20 mm for predicting IC using receiver operating characteristic analysis. • Based on these findings, we developed simple extended biopsy based criteria for predicting IC as follows: (i) PSA level of <20 ng/mL; (ii) Clinical stage ≤ T2a; (iii) 2005 ISUP modified biopsy Gleason score ≤ 6; (iv) CCL/core of <0.20 mm. • The specificity of the criteria was 91%, which was significantly higher than the value from a subset of criteria without item iv (P < 0.001).

Conclusion: • We have developed extended biopsy based criteria for predicting IC incorporating the 2005 ISUP modified biopsy Gleason score and CCL/core.