The Effect of Prostate Cancer Radiotherapy on Testosterone Level: A Systematic Review and Meta-Analysis.

Introduction: In the current study, a systematic search and meta-analysis were performed to evaluate the effect of prostate cancer radiotherapy on testosterone levels of patients. Methods: To illuminate the effect of radiotherapy on the testosterone level of prostate cancer patients, a systematic search was conducted in accordance with the PRISMA guideline in electronic databases of Scopus, Embase, PubMed, Web of Science, and clinical trials up to December 2018 using relevant keywords. Based on a certain set of inclusion and exclusion criteria, 12 eligible studies that had data on the testosterone level following prostate cancer radiotherapy were included in the meta-analysis. Results: According to the various techniques of prostate cancer radiotherapy, the dose values scattered to the testicular tissues ranged from 0.31 to 10 Gy. Combining the findings from 12 studies, it was found that prostate cancer radiotherapy leads to a significant reduction in the testosterone level (Weighted Mean Difference [WMD]: -51.38 ng/dL, 95% CI: -75.86, -26.90, I-2=0.0%, P<0.05). Furthermore, subgroup analysis by the patient number showed a significant reduction in the testosterone level at patient number < 50 (WMD: -80.32 ng/dL, 95% CI: -125.10, -35.55, I-2=0.0%) and 50 < patient number < 100 (WMD: -46.99 ng/dL, 95% CI: - 87.15, -6.82, I-2=0.0%). Subgroup analysis based on treatment technique type revealed a significant reduction in testosterone level after conventional radiotherapy (WMD: -56.67, 95% CI: -100.45,-12.88, I-2=34.3%) and IMRT/SBRT technique (WMD: -57.42, 95% CI: -99.39, -15.46, I-2=0.0%) in comparison with the proton therapy (WMD: 0.00, 95% CI: -80.24, 80.24). Conclusion: The findings showed a significant decrease in the testosterone level of prostate cancer patients after radiotherapy compared with pre-treatment levels.