IBD in men tied to higher prostate cancer risk
Men with inflammatory bowel disease (IBD) were four times more likely to be diagnosed with prostate cancer (PCa) at 10 years than those without IBD, a retrospective analysis has shown.
Researchers sought to evaluate the incidence of any PCa and clinically significant PCa (Gleason grade group ≥2) by randomly matching 1,033 men with IBD with 9,306 controls (median age 53 years) from a single academic medical centre. All participants had undergone at least one prostate-specific antigen (PSA) screening test. Median follow-up times were 6.5 and 4.7 years for cases and controls, respectively. [Eur Urol 2018;doi:10.1016/j.eururo.2018.11.039]
The 5-year incidences of any PCa were 2.8 percent and 0.25 percent for the case and control arms, respectively (log-rank p<0.001); for clinically significant PCa, the rates were 1.6 percent and 0.17 percent, respectively (log-rank p<0.001).
At 10 years, compared with controls, men with IBD continued to have a significantly higher incidence of PCa (4.4 percent vs 0.65 percent, hazard ratio [HR], 4.84, 95 percent confidence interval [CI], 3.34–7.02; p<0.001) and clinically significant PCa (2.4 percent vs 0.42 percent, HR, 4.04, 95 percent CI, 2.52–6.48; p<0.001).
“Diagnosis of low-grade PCa may lead to unnecessary additional treatment or observation,” said the researchers. “Our study is the first to demonstrate an increased risk of clinically significant PCa for men with IBD … this is relevant for a cohort of men with chronic illness [who] may already be subjected to frequent healthcare encounters.”
“It is conceivable that the local or systemic inflammatory state resulting from IBD may lead to chronic prostatic inflammation and, in some cases, eventual development of PCa,” the researchers suggested on the potential mechanism underlying the association.
The systemic inflammatory effect from IBD may trigger elevations in serum acute-phase reactants (ie, C-reactive protein), which have been linked to higher PSA values. [Inflamm Bowel Dis 2004;10:661-665; Prostate 2014;74:561-567] Prostatic inflammation may also elevate serum PSA levels by disrupting the prostate’s cellular architecture, noted the researchers. [J Urol 1997;157:1301-1303; Histopathology 2012;60:199-215] “Subsequent repetitive tissue destruction and regeneration may play a role in the development of PCa,” they said.
However, despite previous evidence showing the potential of a high PSA level to predict increased PCa rates, [JAMA 1997;277:1452-1455] the study did not seem to reflect an IBD-PCa association that is dependent on PSA values or older age, the researchers pointed out.
“These findings highlight the important role of investigating the benefits and harms of PCa screening in high-risk populations. Future studies should seek to determine the appropriate age to begin discussing PCa screening and interpretations of PSA values among patients with IBD,” they said.
Despite the limited data validity and unmeasured variables (ie, IBD disease location, IBD severity markers, family history of PCa, and socioeconomic data) given the study’s retrospective nature, the findings remained significant even after adjusting for confounders, noted the researchers. The large sample size and distribution over a representative age range could have contributed to the significant findings, they added.
The researchers called for further evaluation on the mechanisms linking IBD-related inflammation, PSA levels, and incident PCa to better establish the association between IBD and PCa.