Rationale and design of the CANARI study: a case-control study investigating the association between prostate cancer and 5-alpha-reductase inhibitors for symptomatic benign prostate hypertrophy by linking SNIIRAM and pathology laboratories in a specific region in France.

Benign prostate hypertrophy (BPH) could be associated with low urinary symptoms requiring medical treatment: 5-alpha-reductase inhibitors (5-ARI) or ɑ-blockers. Two clinical trials investigating 5-ARI use in prostate cancer (PCa) primary prevention highlighted a potential safety signal with an increased risk of high-grade PCa. Later observational studies failed to show similar results but have some limits. This paper focuses on describing the protocol of the CANARI study and its feasibility, as regards the matching process of two pseudo-anonymous databases. The study concerned patients living in the Brittany region (France) between 2010 and 2013. We designed a case-control study nested within a cohort of men treated by medical drugs licensed for symptomatic BPH between 2010 and 2011. Cases were patients with incident PCa diagnosed between 2012 and 2013 identified through French Health database (SNIIRAM). Gleason score was searched through Brittany pathology laboratories. Controls were patients without PCa diagnosis. Local pathology laboratories database was constituted in Brittany, gathering Gleason scores. No unique identification number is available in France; linkage of SNIIRAM and Brittany pathology laboratories database was made by deterministic matching. We matched 859 cases to Gleason grading (119 had Gleason score ≥8 and 740 had Gleason <8); around 22% of cases received 5-ARI and 78% α-blockers or phytotherapy. The CANARI study investigated in a population of men treated for BPH the risk of PCa with 5-ARI, according to Gleason grade thanks to SNIIRAM database enriched by local pathological results.