In biopsy-naive patients with prostate-specific antigen (PSA) <10 ng/ml and PI-RADS v2.1 = 3 lesions, researchers sought to create and externally validate a new nomogram.

In Cohort 1 (The First Affiliated Hospital of Soochow University), 307 individuals who had their first biopsy between October 2015 and January 2022 were gathered in hindsight. Around 109 males who satisfied the criteria were part of the external cohort (Cohort 2, Kunshan Hospital) from July 2016 to June 2021. The volume of all lesions was split into 2 subgroups by Slicer-3D Software (PI-RADS v2.1 = 3a and 3b). By examining clinical data from Cohort 1, logistic regression analysis was used to generate a nomogram and search for potential factors. To validate the nomogram in an external cohort, calibration plots, decision curve analyses (DCA), and receiver operating characteristics curve analyses were displayed.

In Institution 1, a total of 70 (22.8%) patients received a prostate cancer diagnosis. About 34 (11.1%) of them had clinically significant prostate cancer (csPCa). Prostate cancer (PCa) and csPCa were predicted by age, prostate-specific antigen density, digital rectal examination, PI-RADS v2.1 = 3 subgroups (3a and 3b), and apparent diffusion coefficient (ADC, <750 mm2/s). In Cohorts 1 and 2, a high area under the nomogram’s curve was seen for PCa (0.857 vs. 0.850) and csPCa (0.896 vs. 0.893). For both internal and external validation of the models, calibration curves demonstrated excellent agreement between the anticipated probability and actual risk. The DCA showed that the nomogram had a net benefit.

It was the first nomogram that, as of yet, could accurately predict PCa and csPCa in biopsy-unexperienced patients with PSA <10 ng/ml and PI-RADS v2.1 = 3 lesions. Additionally, PI-RADS v2.1 = 3 subgroups were regarded in the model as a separate risk factor. The nomogram could help urologists decide whether to do a biopsy on the patients who fall into the so-called “double gray zone.”