Patient-reported outcome and survival in premenopausal hormone receptor-positive breast cancer patients at moderate to high risk: comparing toremifene with aromatase inhibitor in a real-world study

Toremifene, a selective estrogen receptor modulator, is commonly used in China for premenopausal breast cancer patients. This real-world study aimed to compare patient-reported outcome (PRO) and survival between toremifene and aromatase inhibitor (AI) plus ovarian function suppression (OFS) in patients with moderate-/high-risk premenopausal hormone receptor (HR)-positive breast cancer. The primary endpoint was PROs, assessed using SF-36 and EQ-5D-5L questionnaires between January and March 2023. A total of 392 patients were included, with 171 receiving toremifene and 221 receiving AI. The toremifene group showed significantly higher scores in the role physical (p = 0.034) and mental health (p = 0.009) dimensions of SF-36 and lower anxiety/depression (AD) scores (p = 0.038) in EQ-5D-5L compared to AI group. The estimated 5- and 8-year disease-free survival (DFS) rates were similar in toremifene and AI groups: 96.5% versus 91.9%, and 87.4% versus 87.8% (p = 0.39), respectively. Adverse event rates were similar in two groups, except for a greater risk of endometrial thickening (p < 0.001) and a lower occurrence of morning stiffness (p < 0.001) in the toremifene compared to the AI group. Premenopausal HR-positive breast cancer patients receiving toremifene plus OFS had better role physical and mental health outcomes and lower AD dimensions than those receiving AI plus OFS. Both treatments had comparable DFS and favorable tolerability profiles.