Introduction
Tumor contacting with the fibromuscular capsule of prostate means extraprostatic extension. We determine whether a new parameter; the measured distance between fibromuscular capsule and tumor using prostate biopsy core (Distance to tumor; DTT) can predict extraprostatic extension.
Materials and Methods: We analyzed specimens of 82 patients who diagnosed with prostate cancer. All patients underwent pre biopsy prostate MRI and prostatectomy. suspicious lesion of prostate cancer located on transitional zone were excluded. We measured the DTT on each prostate biopsy core and correlated with pathologically confirmed staging and evaluated the concordance between clinical stage with MRI and pathological stage.
Results: mean age was 65.8 years old. Mean prostate specific antigen level was 18.9 ng/ml. There was a positive correlation (r = 0.891, p <0.001) between DTT of prostate biopsy core and pathologically confirmed staging. A receiver operating characteristics curve of the ability of DTT estimated to predict extraprostatic extension revealed the best cutoff value to be 1.0 mm (AUC: 0.85, specificity 75.23%, specificity 91.2%. p = 0.002). Logistic regression analysis revealed that DTT correlated better with extraprostatic extension than tumor volume, Gleason score, prostate specific antigen (PSA) level and tumor. Multiple logistic regression analysis revealed that the predictability of DTT improved by considering PSA value too. Of 82 patients, 53(65.3%) patients did not show prostate capsule invasion in their prostate MRI. However, of these, 15(28.3%) had a pathological capsule invasion in their prostatectomy specimen . Of 15 patients with up-staging, 14 had a less than 1.0mm of DTT.
Conclusions: The distance between tumor and the fibromuscular rim is more significantly related to extraprostatic extension than tumor volume, PSA level and tumor grade. Therefore, in terms of determining clinical stage, The distance would help to predict accurate prostate cancer stage.