Patient Perspectives on Intramuscular Versus Oral Endocrine Therapy in Metastatic Breast Cancer

Endocrine therapy (ET) is a critical component of breast cancer treatment, with both oral and intramuscular (IM) options available to patients. Although these treatments are effective, the 2 modes of administration impact patients’ daily lives in different ways, presenting unique burdens and benefits. This article explores the experiences of patients with metastatic breast cancer using ET, focusing on the challenges of administration and adherence, perceived benefits, and treatment preferences between oral and IM ET.

Adult patients in the United States with a history of taking both oral and IM ET consecutively for at least 3 months for metastatic breast cancer participated in an online survey. Participants were recruited through email and Cancer Support Community’s national network of locations and advocacy groups. The survey collected sociodemographic and clinical information and assessed treatment-related factors such as convenience, pain, time, transportation, cost, access, and impact on eating using a 5-point scale (major burden to major benefit). Participants also indicated their treatment preferences and rated the importance of 11 factors using a 5-point Likert scale when considering metastatic breast cancer treatment options. The results presented in this article are based on interim data analysis.

Interim findings are based on 157 female patients with metastatic breast cancer, with a mean age of 52.6 years (range, 28-78 years). The majority were non-Hispanic White (66.2%), with 28.7% living in urban areas. On average, participants had been living with metastatic disease for 5.9 years, and 58% lived more than 30 minutes from a treatment center. The median duration of ET use was longer for oral ET (24 months) than for IM ET (15 months). More than 80% of respondents indicated that oral ET was less painful, required less transportation and time, and was more convenient compared with IM ET. Additionally, 66% reported that oral ET interfered less with daily life than IM ET (17%). Key benefits of oral ET included ease of access (72%), minimal time commitment (62%), and convenience (57%); the most reported burden was the stress of daily medication (45%). For IM ET, ease of remembering doses was the primary benefit (53%), whereas the most significant burden was injection-related pain or discomfort (84%).

When comparing the 2 treatment options, 67% of participants preferred oral ET, 17% preferred IM ET, 11% expressed no preference, and 5% were unsure. Self-reported adherence was higher for IM ET, with 70% of participants indicating they never missed a dose, compared with 52% for oral ET. For both modes of administration, most patients with missed doses reported missing <3 doses per month. When considering treatment priorities, nearly all participants (96%) identified slowing disease progression as a top priority, followed by the ability to cure the disease (89%) and the impact of treatment on daily life (83%).

The interim results highlight a clear preference for oral ET among patients with metastatic breast cancer, with most participants favoring its convenience, ease of access, and minimal disruption to daily life. However, the need for daily adherence to oral ET was a source of stress for some patients, and self-reported adherence was higher for IM ET. These findings reveal both benefits and burdens associated with each mode of administration. The study underscores the importance of shared decision-making in optimizing treatment strategies to align with patient preferences and priorities, ultimately improving the patient experience in managing metastatic breast cancer.

Source: Fortune E, Newell A, Speck R, et al. Patient experience with intramuscular vs oral endocrine therapy in metastatic breast cancer. Presented at: San Antonio Breast Cancer Symposium 2025. December 10, 2025; San Antonio, TX. Presentation PS1-03-03.