Comparison Of Malignancy And Spatial Distribution Between Latent Prostate Cancer And Clinical Prostate Cance

Objectives:By investigating the characteristics of tumor malignancy and spatial distribution of latent prostate cancer(PCa)and clinical PCa,and comparing the pathological features between latent PCa and clinical PCa,this study aims to investigate whether the tumor pathological origin is consistent,and to verify the clinical significance of criteria of clinically significant tumor.Methods:This study is a cross-sectional study.Prostate specimens that are pathologically diagnosed with PCa are collected by autopsy from postmortem donors in Beijing,China between 2014 and 2021,and patients who went through laparoscopic radical prostatectomy performed in Peking Union Medical College Hospital between 2013 and 2021.In order to avoid the influence of age on the comparison of pathological features of PCa,age matching was performed between the two groups in this study.Each prostate gland was fixed and sliced in step sections.The boundary of cancerous foci was delineated through software.Tumor volume was calculated,and pathological characteristics and spatial location of each cancerous foci were recorded and analyzed in both groups and compared in the two groups.Results:A total of 24 latent PCa were included with a median age of 74 years,and a total of 126 clinical PCa were included with a median age of 71.The median tumor volume of latent PCa was 0.055 ml.In latent PCa,cases with a high-grade tumor accounted for 54.2%(13/24),cases with a tumor volume≥0.5 ml accounted for 12.5%(3/24),and cases with extraprostatic extension(EPE)accounted for 16.7%(4/24).54.2%(13/24)of latent PCa were clinically significant,among which 7 cases were observed as latent PCa with International Society of Urological Pathology(ISUP)grade group 2 and without a large tumor volume or EPE.The median tumor volume of clinical PCa was 2.128 ml.In clinical PCa,cases with a high-grade tumor accounted for 92.1%(116/126),cases with a tumor volume≥0.5 ml accounted for 82.5%(104/126),and cases with EPE accounted for 56.3%(71/126).94.4%(119/126)of clinical PCa were clinically significant.The tumor malignancy between latent PCa and clinical PCa showed significant difference,and there was a 14.65 times higher probability of clinically significant tumor in clinical PCa than in latent PCa.There was no statistically significant difference in the tumor distribution of anterior-prostate and posterior-prostate.The proportion of peripheral zone tumors was significantly higher compared with that of transition zone tumors.Vertically,no significant difference in the distribution was detected for the index tumors,but for all cancerous foci,the number of tumors found in the apex 1/3 and middle 1/3 was significantly higher than that of the base 1/3 of prostate.There was no statistical difference in tumor distribution between latent PCa and clinical PCa.Conclusions:The tumor malignancy of clinical PCa was significantly higher than that of latent PCa,and the spatial distribution of clinical PCa and latent PCa was consistent.Thus,latent PCa can be considered as early-stage PCa.The high proportion in latent prostate cancer of clinically significant tumors,many of which were tumors with ISUP grade group 2 but without a large tumor volume or EPE,suggests that ISUP grade group 2 alone may not be enough for determining clinical significance of the tumor.In this case,tumor volume and EPE should also be taken into consideration for determining tumor clinical significance.