Clinical significance and risk factors of International Society of Urological Pathology (ISUP) grade upgrading in prostate cancer patients undergoing robot-assisted radical prostatectomy

BACKGROUND: The objective of this study is to investigate the clinical significance and risk factors of upgrading in the International Society of Urological Pathology (ISUP) Grade Group System in men undergoing robot-assisted radical prostatectomy (RARP) for prostate cancer. METHODS: A total of 583 patients diagnosed with prostate cancer by systematic biopsy were treated with RARP without neoadjuvant therapy from November 2011 to December 2018. Clinicopathological data were obtained from our clinical records. ISUP grade upgrading (IGU) was defined as ‘ISUP grade in prostatectomy specimen determined to be higher than that in the biopsy specimen’. Clinicopathological factors, including age, PSA, prostate volume at biopsy (PV), PSA density, clinical stage, body mass index (BMI), interval from biopsy to prostatectomy, maximum percentage of cancer involvement per core (%CI), total number of biopsy cores, percentage of cancer positive biopsy cores (%PC), and sampling density were analyzed to detect potential risk factors of IGU. Biochemical recurrence (BCR) rates were calculated to analyze the effect of IGU on cancer prognosis. RESULTS: In univariate analysis, BMI was a positive predictor of IGU, while %CI, %PC, and sampling density were negative predictors of IGU. BMI and %PC were statistically significant predictors of IGU in multivariate analysis. For cases diagnosed as ISUP grade group 2 or higher at biopsy, there was a significant difference in BCR rates between cases with and without IGU. CONCLUSIONS: The results from our cohort showed that elements of both high-grade cancer risk (such as BMI) and sampling efficiency (such as %PC) contribute to IGU. Excluding cases diagnosed as ISUP grade group 1 at biopsy, BCR-free rates were significantly worse in cases with IGU, highlighting the need for more accurate pathological diagnosis at biopsy. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12885-021-08248-y.