The association of maintenance hormone therapy with overall survival in advanced-stage low-grade serous ovarian carcinoma: A risk-set matched retrospective study.

Objective: We conducted a multi-institutional observational study to investigate whether maintenance hormone therapy following primary treatment of low-grade advanced-stage ovarian cancer (LGSOC) is associated with an overall survival advantage. Methods: We included patients with histologically confirmed stage III or IV LGSOC diagnosed between Jan 1, 2004, and Dec 31, 2019, treated in Commission on Cancer-accredited cancer programs in the US. Patients who received hormone therapy within six months of diagnosis were matched to controls who did not initiate hormone therapy during this timeframe by risk-set propensity score matching. The primary outcome was the risk of death from any cause within five years of initiation of HT or observation. Results: There were 296 patients who initiated maintenance hormone therapy within six months of diagnosis and 2805 potential controls. Patients who received hormone therapy were more often treated in academic medical centers (55% vs. 44%), diagnosed later in the study period (62% vs. 23% diagnosed in 2018–2019), and frequently received no chemotherapy during initial treatment (45% vs. 17%). After risk set propensity score matching, we identified 225 patients treated with HT and 225 untreated controls who were otherwise similar with respect to measured covariates. In the matched cohort, hormone therapy was associated with a reduction in the risk of death (hazard ratio 0.60; 95% CI 0.38–0.94), corresponding to a 60-month survival of 75% compared with 65%. Conclusions: Following primary management of LGSOC, maintenance hormone therapy was associated with improved overall survival compared with observation.