Tumor contact length used as a biomarker to predict extracapsular extension, lymph node involvement, and biochemical recurrence.

Abstract

e16588 Background: Prostate cancer (PC) is the cancer most commonly diagnosed in men and the second leading cause of death. Multiparametric magnetic resonance imaging (mpMRI) is the benchmark imaging standard for local staging of PC. Patients with pathological extraprostatic tumor (pEPE) have a worse prognosis than those with confined organ disease with a higher risk of biochemical recurrence (BCR) after radical prostatectomy (RP). These factors, in addition to positive lymph nodes (PLN), are pivotal in the decision-making process regarding treatment. However, the subjective MRI analysis has low sensitivity in the detection of EPE and is plagued by the low interobserver agreement. Tumor contact length (TCL) is an objective parameter of mpMRI defined as the length of prostate cancer in contact with the prostate capsule, which may provide additional information about prostate cancer outcomes. We aimed to evaluate TCL as a predictor of pECE, PLN, and BCR in patients undergoing RP. Methods: In this Institutional Review Board approved single-institution prospective study, we update the follow-up of 148 patients and included 31 new patients, with prostate cancer who underwent prostate MRI before radical prostatectomy from March 2014 to november 2018. TCL was measured using T2-weighted magnetic resonance images.Postoperative prostate-specific antigen (PSA) values were obtained every 3 months in the first year, then biannually and annually thereafter. BCR was defined as PSA≥0.2ng/mL. The exclusion criterion was prior treatment. Results: The median follow-up was 44 months. 76/179 (42,4%) patients had pEPE, 12/179 (6,7%) had pLN, and 29/179 (16,2%) had BCR. TCL values were significantly higher in patients with pathological pECE ( 20,6 mm vs 9,9 mm, p < 0.001). Using a cut-off of 11,9 mm we found area under curve (AUC) of 0,71 to predict pathological ECE, with sensitivity 72,5% and specificity 67,5% . Using a cut-off of 16,5 mm we found AUC of 0,64 to predict BCR, with sensitivity 54,2% and specificity 67,8% and with a cut-off of 21,7 mm the AUC to predict PLN was 0,77, with sensitivity 66,7% and specificity 83,6%. Conclusions: We prospectively demonstrated in our population that TCL values were significantly higher in patients with pEPE , PLN and BCR. If validated, this imaging biomarker may facilitate and inform patient counseling and decision-making.