195 NEGATIVE RESULT IN UNILATERAL 13-CORE BIOPSY CAN PREDICT THE ABSENCE OF SIGNIFICANT CANCER ON THE IPSILATERAL LOBE WITH A HIGH ACCURACY. IMPLICATIONS FOR HEMIABLATIVE FOCAL THERAPY

Abstract

INTRODUCTION AND OBJECTIVES: Multiple studies have revealed that it is difficult to predict the presence of purely unilateral prostate cancer for the purpose of hemiablative focal therapy. However, the contralateral untreated lobe in the prostate exposed to this type of therapy does not have to be a lobe without cancer, but could also be a lobe without significant cancer (SC). The aim of this study is to evaluate the ability of extended 26-core prostate biopsy (3D26PBx: a combination of transrectal 12-core biopsy and transperineal 14-core biopsy) to predict the lobe without SC for the purpose of hemiablative focal therapy. METHODS: We studied 165 patients in whom prostate cancer was diagnosed by 3D26PBx and who underwent radical prostatectomy (RP) without neoadjuvant treatment between 2002 and 2009. RP specimens were divided into right and left lobes, and a total of 330 lobes were analyzed. Pathological specimens were evaluated according to the 2005 ISUP consensus. Considering an upward Gleason score (GS) shift after the 2005 consensus, significant cancer was defined as extraprostatic extension and/or a tumor volume of 0.50 cc or greater and/or GS of 4 3 or greater. We believed that the lobe without SC identified possible areas in which the prostate gland could be preserved without treatment. Whether clinical and pathological variables could be used to predict the lobe without SC was also investigated. RESULTS: The median PSA was 6.6 ng/mL. Biopsy GS were / 6, 3 4, 4 3 and 8 / in 35, 47, 37 and 46 patients, respectively. In the entire cohort, 6.7% of the cases (22/330) revealed the presence of the lobe without cancer while 34% (111/330) revealed the lobe without SC. The positive predictive value (PPV) and negative predictive value (NPV) of unilateral negative biopsy for the lobe without cancer were 22% (19/85) and 99% (242/245) in 3D26PBx, respectively. The PPV/NPV/sensitivity/specificity of unilateral negative biopsy for the lobe without SC were 85/77/56/94% in 3D26PBx, respectively. In the cohort of biopsy negative side, standard clinical variables including prostate-specific antigen, prostate volume, digital rectal examination findings and age were not significantly associated with the lobe without SC. CONCLUSIONS: With PPV of 85%, 3D26PBx predicted the lobe without SC. If follow-up treatment of the contralateral untreated lobe was appropriately performed, hemiablative focal therapy may be a reasonable option in patients with a cancer negative side, as detected by 3D26PBx, and with suspected organ-confined disease.