Correlation Between Serum Prostate-Specific Antigen and Testosterone Following Bilateral Total Orchidectomy for Patients with Advanced Prostate Cancer in Jos, Nigeria

BACKGROUND: Prostate cancer is a common malignancy affecting men beyond the middle age. Monitoring of treatment of the disease using serum testosterone and prostate-specific antigen (PSA) offers an index of treatment efficacy and a reflection of disease progression, respectively. The objective of this study was to determine the relationship between changing values of serum PSA and serum testosterone in patients with advanced prostate cancer following bilateral total orchidectomy (BTO). MATERIALS AND METHODS: This was a prospective longitudinal study carried out over a 1-year period among patients who met the inclusion criteria. Each patient underwent detailed clinical evaluation including history, as well as physical examination with digital rectal examination of the prostate. Also, samples of serum PSA and testosterone were obtained and sent to the same chemical pathology laboratory before intervention with BTO, then at 2, 4, and 6 months. The values of serum PSA and testosterone were obtained and changes over this period were compared for both parameters. The analyses included independent inferential analysis of serum testosterone and serum PSA over a period of 6 months and a correlation of the two parameters over the same period. Results were analysed using SPSS version 23. P value of <0.05 was regarded significant. Charts and tables were used for data expression. Kruskal–Wallis and Wilcoxon tests were used for individual inferential analysis of serum testosterone and PSA. The Spearman ranked correlation coefficient test was used to determine the degree of correlation of serum testosterone and serum PSA levels while Pearson correlation coefficient test was used to determine the degree of correlation between the percentage changes in serum testosterone and PSA measured over the period of the study. RESULTS: A total of forty-two men with mean age of 68.49 ± 8.86 years who had advanced prostate cancer were recruited. The histologic type of prostate cancer diagnosed for all the patients was adenocarcinoma. The mean Gleason score was 7.98 ± 1.09, while the modal Gleason grade group represented was grade group 5. There were statistically significant changes in serum testosterone and PSA levels in response to bilateral total orchidectomy with P value of <0.001. However, there was no statistically significant correlation between serum testosterone and serum PSA levels following bilateral total orchidectomy with p values of 0.492, 0.358, 0.134, and 0.842 at baseline, 2, 4, and 6 months, respectively. There was a significant correlation between the percentage changes in serum testosterone and PSA measured between baseline and 2 months with P value of <0.001. However, there was no statistically significant correlation between the percentage changes in serum testosterone and PSA measured between baseline measured against 4 months and 6 months with P value of 0.998 and 0.638, respectively. CONCLUSION: The study showed that reduction in serum levels of testosterone and PSA following BTO was significant. It also revealed no statistically significant correlation between serum testosterone and serum PSA measured over 6 months following bilateral total orchidectomy.