Prostate cancer (PC) remains the leading malignancy among men. The status of patients initially diagnosed with a Gleason score of (3 + 3) 6 based on biopsy results is becoming increasingly questioned. Can ISUP 1 be considered "NOTcancer"? Various additional diagnostic methods can be the key not only to establishing a PC diagnosis, but also to predicting the grade of cancer differentiation at the pre-invasive stage. The aim of the study was to assess the correspondence between biopsy and postoperative Gleason scores in patients with Gleason (3 + 3) 6, and to study the pathological characteristics of true ISUP 1.

The study analyzed data from 225 patients who underwent radical prostatectomy (RP) between 2018 and 2024. The average patient age was 65 ± 6 years, median PSA level was 8.7 ng/ml, and median prostate volume was 55 cm³. All patients initially had a biopsy Gleason score of (3 + 3). All histological material (biopsy, surgical) was examined in one laboratory. Histological examination of surgical specimens was performed in accordance with national clinical guidelines.

In 54.22 % of patients (n 122), the postoperative Gleason score increased to ≥ 7. ISUP groups 4 (n 8) and 5 (n 3) were identified in 4.89 % of cases, and pattern "5" was found in 1.33 % of patients. In all 103 true ISUP 1 cases (45.78 %), characteristic pathological features of cancer were identified: atypical glands, nuclear changes (hyperchromasia, mitotic figures, apoptotic bodies), cytoplasmic changes, stromal response to carcinoma, mucinous fibroplasia, glomerulations, perineural invasion, basal cells.

True ISUP 1 has all the morphological characteristics of cancer. More than half of the patients with a biopsy Gleason score of (3 + 3) 6 had a higher final Gleason score upon histological examination.

This confirms the need to improve existing diagnostic and treatment approaches for this patient category