Background Poly (ADP-ribose) polymerase inhibitors (PARPi) play a pivotal role in ovarian cancer management. With medical cannabis emerging as a novel component of supportive care, this study investigated the impact of medical cannabis use on oncological outcomes in patients with ovarian cancer undergoing PARPi therapy.

Methods The study included patients from a single institution database treated for ovarian cancer between January 2014 and January 2020 who received PARPi maintenance therapy in a first-line or recurrent disease setting after a confirmed response to platinum-based treatment. The study categorized patients as cannabis users and cannabis-naïve. Univariate and multivariate Cox regression analysis and the Kaplan–Meier method were used to assess the effects of medical cannabis use on the duration of PARPi therapy, progression-free survival, and overall survival.

Results Among the eligible patients (n=93), most were cannabis-naïve (69%, n=64) while the rest used medical cannabis (31%, n=29). Medical cannabis use rates were comparable for patients receiving PARPi therapy post-primary treatment or for recurrence (42%, n=9, vs 27%, n=20; p=0.1). Both groups exhibited similar median duration for PARPi therapy (12.1 vs 9.5 months; p=0.89) and progression-free survival (20 vs 21 months; p=0.83). Kaplan–Meier analysis detected no differences in progression-free survival associated with cannabis use. Although cannabis users had an extended overall survival compared with the cannabis-naïve group (129.3 vs 99 months; p=0.03), cannabis use was insignificant for overall survival on multivariate analysis (p=0.10). Multivariate analysis showed stage IV at diagnosis (p=0.02) to be the sole factor associated with progression-free survival (p=0.02).

Conclusion Medical cannabis usage in patients receiving PARPi treatment showed no association with duration of PARPi therapy, progression-free survival, or overall survival.