Sexual Function in Breast Cancer Survivors: A Case–Control Study Using the Female Sexual Function Index

Background: Sexual dysfunction is a common but often under-addressed concern among breast cancer survivors and may substantially affect quality of life. Evidence specifically addressing sexual function in premenopausal survivors remains limited. This study aimed to evaluate sexual function in premenopausal breast cancer survivors compared with healthy women and to identify factors associated with sexual dysfunction during survivorship. Methods: A cross-sectional case–control study was conducted in 80 premenopausal women, including 40 breast cancer survivors and 40 healthy controls, recruited from hospital-based clinics in Spain. Sexual function was assessed using the Female Sexual Function Index (FSFI). Sociodemographic and clinical variables were collected. Between-group comparisons were performed using appropriate statistical tests, and logistic regression analysis was used to evaluate associations. Results: Breast cancer survivors showed significantly lower total FSFI scores compared with controls (median 26.1 vs. 31.4; p < 0.05), with impairments observed in the domains of desire, arousal, lubrication, satisfaction, and pain. Sexual dysfunction (FSFI ≤26.55) was identified in 55% of survivors and 10% of controls. Breast cancer survivorship was significantly associated with sexual dysfunction (odds ratio [OR]: 11.0; 95% confidence interval [CI]: 3.29–36.80). No significant differences were observed according to type of surgery or treatment-induced menopause. Conclusions: Breast cancer survivorship was associated with significantly higher odds of sexual dysfunction across multiple domains of sexual health. These findings highlight the need for routine assessment and management of sexual function as part of survivorship care.