Abstract A108: Aspirin and non-steroidal anti-inflammatory medication and survival following an ovarian cancer diagnosis: A Norwegian nationwide registry-based cohort study

Abstract Aspirin and non-aspirin non-steroidal anti-inflammatory (NSAID) drugs have been associated with survival in women with a history of epithelial ovarian cancer (EOC). Studies to date are generally limited to self-reported exposure data and with limited data by disease histotype. We conducted a registry-based cohort study including EOC incidence and disease characteristics from the Cancer Registry of Norway and prescription data from the Norwegian Prescription Database; the study was restricted to incident invasive EOC cases. These registries cover more than 99% of the Norwegian population and include all patients in an unselected manner. Patients’ follow-up started 10 months after diagnosis (baseline). We analyzed exposure in two ways: a) fixed-in-time exposure: women who received three consecutive prescriptions between 1 month and 10 months after diagnosis were coded as baseline users; the others were coded as baseline non-users; b) time-dependent exposure: women who received three consecutive prescriptions were coded as current users from the third prescription date; women who stopped using that drug became past users until the end of follow-up or became current users again if a new prescription was observed; women who never received three consecutive prescriptions were coded as never users; to avoid reverse causation, prescriptions were lagged by ten months. The main outcome measure of the study was overall survival, evaluated among all EOC cases and high-grade serous cases separately. Multivariable Cox-proportional hazard models were used to model survival, controlling for age at diagnosis, histology groups (for models including all cases), stage, ethnicity, education, marital status, and use of other medications at baseline (medications indicated for cardiovascular disease, statins and anti-diabetics). A total of 4325 invasive EOC cases were identified, with 2206 deaths (1973 disease-specific). We observed no association between aspirin use at baseline and survival following an ovarian cancer diagnosis (e. g. , current vs. never use, all cases: aspirin, HR 1. 01 (95% CI: 0. 69-1. 48) ; high-grade serous cases, HR: 0. 74 (0. 41-1. 35) ). Inverse associations were observed between aspirin and survival in the time-varying exposure models (e. g. , all EOC cases: aspirin, HR 0. 65 (0. 54-0. 78) ; high-grade serous, HR: 0. 57 (0. 45-0. 73) ), and with inverse associations observed with higher post-diagnosis prescribed cumulative defined daily dose of aspirin. No associations were observed between current NSAID use and survival following an ovarian cancer diagnosis, overall or among high-grade serous cases. Higher post-diagnosis prescribed cumulative defined daily dose of NSAIDs was associated with poorer survival. This study provides further evidence of a potential beneficial effect of aspirin use for survival following an ovarian cancer diagnosis, observing similar associations for ovarian cancer overall and in the subgroup of women diagnosed with tumors of the high-grade serous histotype. No evidence of an inverse association for NSAID use was observed. Citation Format: Nathalie C. Støer, Kristina Lindemann, Edoardo Botteri, Hilde Langseth, Renée Turzanski Fortner. Aspirin and non-steroidal anti-inflammatory medication and survival following an ovarian cancer diagnosis: A Norwegian nationwide registry-based cohort study abstract. In: Proceedings of the AACR Special Conference on Ovarian Cancer; 2023 Oct 5-7; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84 (5 Suppl₂): Abstract nr A108.