Correlation of Tumor Location and Biochemical Recurrence in Localized and Locally-Advanced Prostate Cancer in Post- Robotic Radical Prostatectomy Patients

Abstract

Objective: This study aims to determine the tumor location of prostate adenocarcinoma in patients who underwent Robotic Radical Prostatectomy (RRP) for localized and locally-advanced prostate cancer and the correlation of the tumor location with the incidence of biochemical recurrence.

Patients and Methods: The authors reviewed the patient database of a single Urological Oncologist from January 2015 to April 2017 for patients who underwent RRP for localized or locally-advanced prostate cancer. They also reviewed the histopathologic report of the prostatectomy specimens to determine pathologic T-stage, prostate volume, and post-operative Gleason score. The histopathologic examination of specimens was interpreted by a single Urological Pathologist based on the 2014 International Society of Urological Pathology Gleason Scoring System. Eligible patients were then divided into three groups: those with pure anterior tumor location, pure posterior tumor location, and mixed tumor location. Presence of positive surgical margins, mean follow-up period, and biochemical recurrence were determined for these groups. Patient demographic data were analyzed using test of proportions. Correlation of tumor location with biochemical recurrence was derived using Pearson chi-square test.

Results: Of the 113 patients included in the study, 63 (55.8%) were clinically-staged T2 patients while 27 (23.9%) and 23 (20.3%) were clinical stage T1 and T3, respectively. On pre-operative prostate biopsy, 27 (23.9%) patients had a Gleason score of 8-10. Thirty-eight (33.6%) and 30 (26.6%) had a Gleason score of 6 (3+3) or 7 (3+4), respectively Average prostate volume was 42.8 grams. Ninetyfive (84.1%) of the patients had mixed tumor location, 11 (11.6%) had pure posterior tumor location, and only 7 (6.2%) had pure anterior tumor location. In those with pure anterior or posterior tumor locations, majority were low-grade prostate cancers (Gleason 6(3+3) and Gleason 7(3+4)) while those with mixed tumor location had low to high-grade prostate cancers (Gleason 7 (3+4) and Gleason 7 (4+3.)) Majority of the patients had pathologic T2c and T3a tumors across all groups. Positive surgical margins were present in 31% of those with mixed tumor location and only 0.9% in those with pure anterior or posterior tumor location, respectively. Only 10 patients from the population had biochemical recurrence, 9 of which had mixed tumor location while 1 had pure posterior tumor location. Pearson chi-square test shows no significant relationship between tumor location and biochemical recurrence at 95% CI (p= regional involvement 0.695.) Furthermore, there is a very weak positive correlation (R=0.069) between tumor location and biochemical recurrence.

Conclusion: Majority of patients who underwent RRP have mixed tumor location. There is poor correlation between prostate cancer tumor location and biochemical recurrence.