Conclusion
An association was found between the reducing M/C ratio or morning urinary melatonin-sulfate levels and the risk of prostate cancer. We also found that patients whose M/C ratios and PSA levels beyond 10 ng/mL were low had much higher risk of advanced (end-stage) disease and prostate cancer. Due to this cross-sectional and case-control nature of the study, it was not possible to establish an accurate causal relationship between prostate cancer risk and the urinary M/C ratio. These results can be confirmed with some larger prospective cohort studies.