Risk of prostate cancer in men with spinal cord injury: a systematic review and meta-analysis

A lower risk of prostate cancer has been reported in men with spinal cord injury (SCI) as compared to that observed in able-bodied subjects. As injury-related consequences can have opposite effects on prostate pathophysiology, this meta-analysis aimed to (1) establish the existence/quantify the extent of decreased prostate cancer risk following SCI and (2) find out if there is any statistically significant difference in prostate-specific antigen (PSA) levels between SCI and able-bodied subjects. MEDLINE, Cochrane Library, Scopus, CINAHL, and ScienceDirect databases were used. Only studies reporting a prostate cancer diagnosis and/or PSA levels following SCI and in able-bodied controls were included. Five studies provided information about prostate cancer on 35 293 subjects with SCI and 158 140 controls. Six studies were included in PSA analysis which reported information on 391 men with SCI and 1921 controls. Pooled estimates indicated that SCI reduced the prostate cancer risk by approximately 50% as compared to controls, whereas differences in PSA levels were not statistically significant. Funnel plots suggested the presence of publication bias only in PSA analysis. Between-study heterogeneity was established and when, according to meta-regression models, analysis was restricted to studies including men with mean age over 55 years, prostate cancer risk in SCI decreased up to 65.0% than that in controls with no heterogeneity (P = 0.33, I(2) = 9%). In conclusion, in men over 55 years old, SCI decreases the prostate cancer risk up to 65.0% than that in controls. The large between-study heterogeneity on PSA confirms its poor reliability as a screening tool for prostate cancer in SCI.