A proposal of a new nomogram for predicting upstaging in contemporary D'Amico low-risk prostate cancer patients

PURPOSE: Unfavorable prostate cancer (PCa) disease at final pathology affects at least 10 % of D'Amico low-risk patients. Thus, conservative therapies including active surveillance may be wrongfully applied. The purposes were to assess the rate of upstaging in a contemporary cohort of D'Amico low-risk PCa patients and to develop and externally validate a nomogram as upstaging prediction tool in two European cohorts.

METHODS: Analyses were restricted to 2007 patients who harbored low-risk PCa at ≥10-cores initial biopsy according to D'Amico classification (PSA <10.0 ng/ml, Gleason score <7 and clinical stage ≤T2a). Patients underwent radical prostatectomy at a high-volume center in Hamburg, Germany, from 2010 to 2015. The Hamburg cohort was randomly divided into development (n = 1338) and validation cohorts (n = 669). The development cohort was used to devise a nomogram predicting upstaging, defined as presence of ≥pT3 and/or lymph node invasion. The nomogram was externally validated in two European validation cohorts (Hamburg, n = 669; Milan, n = 465).

RESULTS: Upstaging was observed in 187/1338 (14.0 %) of low-risk patients. In multivariable models, four of ten tested variables achieved independent predictor status: age (OR 1.07, 95 % CI 1.04-1.09), PSA (OR 1.21, 95 % CI 1.12-1.31), prostate volume (OR 0.97, 95 % CI 0.96-0.98) and percentage of positive cores (OR 1.02, 95 % CI 1.01-1.03). In external validation, the nomogram demonstrated 70.8 % (Hamburg) and 70.0 % (Milan) accuracy, respectively, with excellent concordance between predicted and observed values.

CONCLUSIONS: Our proposed nomogram is capable to accurately identify D'Amico low-risk patients at risk of upstaging, utilizing four routinely available clinical variables, age, PSA, prostate volume and percentage of positive biopsy cores. Unfavorable prostate cancer disease at final pathology affects at least 10 % of D'Amico low-risk patients. Thus, we developed and externally validated a new nomogram based on contemporary low-risk prostate cancer patients to accurately identify D'Amico low-risk patients at risk of upstaging. It utilizes four routine variables, age, PSA, prostate volume and percentage of positive biopsy cores.