Objective: to determine the degree of heterogeneity of prostate cancer Gleason 6 (3 + 3) by assessing: long-term oncological results, mismatch of pre- and postoperative degree of prostate cancer aggressiveness, preoperative clinical component.Materials and methods. 528 patients with clinically localized prostate cancer and Gleason»s preoperative score of 6 (3 + 3). All patients were divided into 3 groups: group 1 (n = 151) — Gleason 6, prostate specific antigen (PSA) density <0.15ng/ml/cm3, ≤4 positive biopsy cores, <50 % lesion of the biopsy cores, group 2 (n = 229) — Gleason 6, PSA <10 ng/ml and group 3 (n = 148) — Gleason 6, PSA >10 ng/ml.Results. Statistically significant differences between group 1 and group 2 were observed only when assessing PSA velocity (p <0.017). The median time to the development of biochemical relapse (BCR) in the study population was 12 (3—77) months. BCR in group 1 was observed in 1.98 % of patients, in group 2 and 3 — 7.86 and 14.19 %, respectively. Statistically significant differences in the time of onset of BCR within 2 years after surgery were found between groups 1 and 2 (p = 0.002) and group 1 and 3 (p = 0.0001). An increase in the degree of malignancy after surgery in group 1 was determined only in 13 % of patients, in group 2 in 27 %, in group 3 in 43 % of patients. The contribution of a greater postoperative degree of malignancy of prostate cancer to the development of BCR in group 1 was 1.32 % (2 out of 3 patients). Thus, in group 1 in the case of true Gleason 6 (3 + 3), the probability of BCR was 0.66 %.Conclusion. PSA velocity before surgery showed a statistical difference between groups 1 and 2. Based on long-term oncological results after surgery, heterogeneous behavior of the tumor is observed among the study groups. Group 1 in comparison with group 2 and 3 showed the lowest frequency of increase in the Gleason score and the likelihood of developing BCR after surgery. These results may be useful in planning an individual patient treatment plan.
