Second primary cancers and hormonal therapies for prostate cancer: A nested case-control study

(Pre-)clinical studies have not ruled out a potential risk of second primary cancer (SCP) under the effect of some new androgen receptor pathway inhibitors (ARPIs), especially enzalutamide (ENZ).

Using the French health reimbursement claims database (Système National des Données de Santé), we designed a case-control study nested in a 2013-2020 cohort of new users of androgen-deprivation therapy. The cases were patients with a first diagnosis of SPC, identified beyond 12 months following cohort entry and up to December 31st^, 2021; up to 10 controls were matched per case, based on age and cohort entry date. The main analysis focused on patients who had not switched to a different ARPI. Applying a one-year lag time, we determined the most frequent and longest cumulative exposure patterns to abiraterone (ABI) or ENZ and estimated the odds ratios.

The cohort comprised 147 092 patients, including 7928 cases and 78 554 controls eligible for analysis. The SPCs mainly involve the digestive organs, the urinary tract, or the lungs. Recent and short exposure to ENZ was associated with SPC: OR 1.7, 95% CI [1.2-2.4]. Recent one full year of exposure to ABI, as well as full-year plus part of the second year, was associated with SPC: OR 1.8 [1.2-2.7] and 2.3 [1.3-4.0], respectively.

SPC cases were mainly observed among recently exposed patients, which could be linked to a detection bias. The insufficient number of patients exposed over many years means that no definitive conclusions can be drawn.