Discussion
The goal of this study was to establish testing rates and analyze PSA testing trends across races and age groups in veterans with SCI. This is the largest cohort of patients with SCI analyzed in the literature. The key findings of this study were that despite clear AUA guidelines recommending against PSA testing in patients aged ≤ 39 years and ≥ 70 years, there are high rates of testing in veterans with SCI in these age groups (0.46 tests per year in those aged ≤ 39 years and 0.91 tests per year in those aged ≥ 70 years). In terms of race, as expected based on increased risk, African American veterans with SCI had higher PSA test rates.18 However, the continued increase in PSA testing rate for African American veterans aged ≥ 70 years was unexpected and not seen in other racial groups. As racial disparities are known to affect prostate cancer outcomes in African American men, it is reassuring that PSA testing was actually higher among African American men with SCI in our population, suggesting this vulnerable population is not being left behind in terms of screening.17 In contrast to other studies that show a lower rate of PSA screening in patients with SCI, our study suggests general PSA overtesting in veterans with SCI and a need for improved education for both veterans and their health care practitioners.19
Prostate Cancer Incidence
Although the exact mechanism behind alterations in prostate function in the SCI population have yet to be fully elucidated, research suggests that the prostate behaves differently after SCI. Animal models of prostate gland denervation show decreased prostate volume and suggest that SCI may lead to a reduction in prostatic secretory function associated with autonomic dysfunction. Shim and colleagues hypothesized that impaired autonomic prostate innervation alters the prostatic volume and PSA in patients with SCI.10
Additional studies looking at actual PSA levels in men with SCI reveal conflicting data.10-15,20 Toricelli and colleagues retrospectively studied 140 men with SCI, of whom 34 had PSA levels available and found that mean PSA was not significantly different for patients with SCI compared with controls, but patients using clean intermittent catheterization had 2-fold higher PSA levels.21 In contrast, Konety and colleagues found that mean PSA was not significantly different from uninjured controls in their cohort of 79 patients with SCI, though they did find a correlation between indwelling catheter use and a higher PSA.22
Studies have shown an overall decreased risk of prostate cancer in patients with SCI, though the mechanism remains unclear. A large cohort study from Taiwan showed a lower risk of prostate cancer for 54,401 patients with SCI with an adjusted hazard ratio of 0.73.23 Patel and colleagues found the overall rate of prostate cancer in the population of veterans with SCI was lower than the general uninjured VA population, though this study was limited by scope with only 350 patients with SCI.24 A more recent systematic review and meta-analysis of 9 studies evaluating the prevalence of prostate cancer in men with SCI found a reduction of up to 65% in the risk of prostate cancer in men with SCI, and PSA was found to be a poor screening tool for prostate cancer due to large study heterogeneity.16