Investigation of the relationship between prostate specific antigen doubling time and the severity of a malignant tumor of the prostate

Background: Prostate cancer has been reported as a worldwide important kind of cancer and the second most common cause of cancer-related mortality among men. Prostate-specific antigen (PSA) serum level is one of the most important markers of prostate cancer diagnosis. While PSA level helps predict the risk of prostate cancer development, researchers still looking for ways to increase the accuracy of prognostic models. To increase the specificity of PSA and decrease of unnecessary biopsies and morbidity, PSA-related parameters such as PSA doubling time (PSADT) have been used. In this study, the relationship between this factor and the severity of prostate cancer was evaluated. Methods: In this retrospective study, the data of patients who were subjected to transrectal ultrasound-guided (TRUS) biopsy of the prostate and referred to Imam Khomeini Hospital, Tehran, between 2009 and 2017 were reviewed. We enrolled the men with at least two consecutive elevated PSA level within three months to calculate PSADT. Based on the pathology report, primary and secondary Gleason score (GS) were determined. Correspondingly, considering GS, the patients were divided into two groups with high-grade and low-grade tumor (GS<7 considered as low-grade and GS>7 considered as high-grade tumor). Results: Totally, 1712 cases of TRUS biopsy of the prostate were studied. Among them, 547 (32.3%) had prostate cancer, of whom 73 cases were eligible based on inclusion criteria and were consented to enroll in the study. According to the data obtained, we found a significant difference in PSADT between the two groups of patients with high-grade and low-grade malignancy (mean±SD PSADT, 9.8±14.2 vs. 16.1±14.9 respectively, P=0.004). Considering the seven months as the cut-off point for PSADT in determining malignancy, there was a significant difference between the two groups according to Fisher's exact test (P=0.01). Conclusion: In our study, PSADT cut-off of 7 months provided the greatest accuracy for differentiation between low-grade and high-grade malignancy, and PSADT has acceptable accuracy for the diagnosis of high-grade tumors.