Detection of Prostate Specific Antigen Density (PSAd) using RIA method in Prostate Cancer diagnosis and Its clinical significance

Abstract

Background: Prostate cancer does not have symptoms in its early stages, most cancers are diagnosed through active surveillance and early detection. According to the 2018 GLOBOCAN study, 1,276,106 new cases of prostate cancer and 358,989 deaths were reported annually in the world, accounting for 7.1% of all male cancer cases, and the number of cases is higher in developed countries. In Mongolia, the incidence of prostate cancer has been increasing over the past 10 years, and the cancer is mostly diagnosed at a late stage. Digital Rectal Examination (DRE) and serum Prostate Specific Antigen (PSA) levels are widely used in the diagnosis of prostate cancer worldwide. In the diagnosis of prostate cancer, the combined use of the method of serum PSA level, DRE and Trans Rectal Ultrasound guided Biopsy (TRUS Biopsy) is considered to be the gold standard of diagnosis. PSA is a tumor marker with diagnostic sensitivity and advantages, but limited in some cases. Therefore, by calculating the Prostate Specific Antigen density (PSAd), it is possible to determine the possibility of prostate cancer in patients whose PSA level is in the grey zone in a simple and safe way, and avoid unnecessary injections. Aim: To estimate PSAd and compare diagnostic sensitivity with other diagnostic methods Materials and Methods: In this retrospective study, 58 patients were included who were with high PSA level and TRUS guided Biopsy analysis at Nuclear medicine Department, Diagnostic Imaging Center, First central hospital of Mongolia from May 2017 to November 2020. Based on the results of biopsy analysis, we divided the patients into 3 groups according to the diagnosis of prostate cancer, atypical small acinar proliferation (ASAP) and benign prostate hyperplasia (BPH), and calculated PSAd in each group, and compared the sensitivity of the PSAd diagnosis to the sensitivity of the PSA marker of the prostate cancer and the features of TRUS diagnosis. Statistical analysis was performed using SPSS 22.0 and Graph Pad Prism 8.0 software. Results: The average age of 58 patients in the study was 66.7±7.6 year patients (46.5%) were diagnosed with prostate cancer, 9(21%) were with ASAP, and 14(32.5%) were with BPH. The PSA level was 33.1±25.4 ng/ml in the group with prostate cancer and was not statistically significant (p=0.13) compared to ASAP, and was significantly different compared to the group with BPH (p<0.01 ). The amount of PSAd was determined in the group with cancer - 1.59 ng/ml/cc; in the group with ASAP - 0.29 ng/ml/cc; and in the group with BPH - 0.27 ng/ml/cc, and the group with prostate cancer was statistically significant compared to other groups (p=0.04, p=0.001), there was no statistical significance or no obvious difference between the two groups without cancer. The sensitivity of PSA diagnosis is 90.9%, the specificity is 75%, the sensitivity of PSAd diagnosis is 78.6%, and the specificity is 70%. Conclusion: Prostate-specific antigen density (PSAd) varies among clients with elevated serum PSA levels. Calculating PSAd has more diagnostic value than PSA alone in the early diagnosis of prostate cancer. Comparing the response of clients who underwent TRUS Biopsy to PSAd is considering to be significant in clinical practice to reduce the number of unnecessary biopsies.