[Microfocal prostate cancer: a clinicopathological analysis of 206 cases]

Objective: To investigate the clinical and pathological features and prognosis of patients with microfocal prostate adenocarcinoma. Methods: Clinical and pathological data of the patients diagnosed with microfocal adenocarcinoma on prostate biopsy at the West China Hospital from 2013 to 2019 were collected. Microfocal adenocarcinoma was defined as follows: Gleason score of 3+3=6, total number of the cores ≥10, number of the positive cores ≤2, and proportion of the tumor in each positive core<50%. Clinicopathological parameters, treatment plans and follow-up data were collected. Pathological information of the biopsy and radical resection specimens was used to analyze the correlation between pathological parameters in the biopsy report and adverse pathological features of radical resection specimens, including increased Gleason score, capsule invasion, positive surgical margin and perineural invasion. Results: A total of 206 cases of microfocal adenocarcinoma were diagnosed on prostate biopsies from 2013 to 2019, accounting for 6.7% of all adenocarcinoma cases. There were 139 cases of 1 positive core and 67 cases of 2 positive cores. Patients with microfocal adenocarcinoma were younger than those with non-microfocal adenocarcinoma (69 years versus 71 years, P<0.001). Compared with patients with non-microfocal adenocarcinoma, the pre-biopsy total prostate specific antigen (tPSA) and free prostate specific antigen (fPSA) levels in patients with microfocal adenocarcinoma were both lower (11.2 μg/L² versus 23.7 μg/L²; 1.4 μg/L² versus 3.0 μg/L², P<0.001), the fPSA/tPSA level was higher (12.9% versus 10.7%, P<0.05), the prostate volume was larger (38.9 mL versus 34.3 mL, P<0.05), and the PSA density was lower (0.3 μg/L² versus 0.8 μg/L², P<0.001). 130 patients underwent radical prostatectomy, 30 patients chose active monitoring, 31 patients chose endocrine or radiation therapy, and 15 patients were lost to follow-up. Three patients in the active surveillance group underwent radical prostatectomy for disease progression after 21-39 months observation. Biochemical relapses occurred in two patients in the radical prostatectomy group. The remaining patients have no disease progression or recurrence at present. Compared with radical prostatectomy specimens, Gleason score in the biopsy material was increased in 64/115 patients (55.7%). Among resection excision specimens, 14 cases (12.2%) had extraprostatic extension (EPE), 35 cases (30.4%) had perineural invasion, and 16 cases (13.9%) had a positive margin. Univariate and multivariate analyses showed that low fPSA/tPSA ratio and 2 positive cores were independent risk factors for Gleason score increase in the radical prostatectomy specimens. A low fPSA/tPSA ratio was an independent risk factor for perineural invasion. Low fPSA/tPSA ratio and low prostate volume were associated with a positive margin in radical prostatectomy specimens. Conclusions: In this study, patients diagnosed with microfocal adenocarcinoma on prostate biopsy account for a high proportion of the patients with increased Gleason score in the radical prostatectomy specimens, and there is a certain proportion of adverse pathological features in the radical specimens. Therefore, for the patients with only a small amount of low-grade adenocarcinoma found in biopsy, PSA levels and PSA density should be taken into consideration in treatment selection.