278P Exploring quality of life in women with early breast cancer: A multi-center cross-sectional study

Adjuvant endocrine therapy (AET) presents a crucial preventive treatment in women with hormone receptor-positive early breast cancer (BC), spanning a recommended duration of 5 to 10 years. However, its efficacy is accompanied with a burden of estrogen depleting adverse effects leading to reduced quality of life (QoL). Since compromised QoL poses a significant barrier to adherence to AET, this study aims to investigate factors influencing QoL during AET and their association with adherence. This multi-centred cross-sectional study was conducted across multiple clinical sites and online in collaboration with Croatian BC patient associations (NCT06192446). Validated questionnaires were used to assess the QoL (Functional Assessment of Cancer Therapy - Endocrine Symptoms - FACT-ES) and adherence (Medication Adherence Report Scale - MARS-5). Adherence was defined as taking all prescribed medication doses. Data analysis was performed using SPSS v. 29 (p≤0.05). A total of 847 eligible participants (median age 52 years, median AET duration 2 years) completed the FACT-ES questionnaire. QoL correlated positively with participants' age (p=0.000) and negatively with a duration of AET (p = 0.050). Premenopausal status (p<0, 001), switching AET (p<0, 001), and gonadotropin-releasing hormone co-medication (p=0.015) were linked to lower QoL. Adherent participants demonstrated higher QoL (p<0.001) with fewer side effects (p<0.001). The side effects most strongly associated with non-adherence included vaginal discharge, vaginal itching/irritation, weight gain, bloating, mood swings, and irritability (p<0.001). Side effects significantly linked to intentional non-adherence encompassed dizziness (p=0.014), vomiting (p=0.027), diarrhoea (p=0.006), bloating (p=0.024), and breast sensitivity/tenderness (p=0.003). QoL and adverse effects are factors linked to non-adherence to AET. Implementing tailored strategies to mitigate specific adverse effects and providing comprehensive care to enhance overall QoL may contribute to improving adherence to AET.