Patients With Breast Cancer Treated With Aromatase Inhibitors Experience Musculoskeletal Pain

A majority of patients with breast cancer treated with aromatase inhibitors (AI) in the first 18 months of therapy experienced persistent mild or moderate pain and musculoskeletal symptoms, according to research presented at the 48th Oncology Nursing Society (ONS) Congress in San Antonio, Texas.

Most post-menopausal women with breast cancer have positive hormone receptors.¹ Because of this, the National Comprehensive Cancer Network Guidelines recommend this patient population receive artificial intelligence (AI) for 5 to 10 years. However, a large percentage of these patients report AI-associated musculoskeletal syndromes (AIMSS), which includes joint pain, muscle pain, and muscle stiffness. As a result, AIMSS is a major contributor to the high discontinuation rate of AI treatment among patients with breast cancer.

To dig deeper into this patient population’s musculoskeletal pain, Yehui Zhu, PhD, and colleagues² longitudinally examined the inter-individual variability of musculoskeletal pain and its predictors during the first 18 months of AI therapy among postmenopausal women with breast cancer.

“To the authors’ knowledge, this is one of the first studies to characterize the longitudinal inter-individual variability and its protective/risk predictors to musculoskeletal pain with AI therapy in breast cancer,” the researchers wrote.

In a cohort study, researchers assessed pain and musculoskeletal symptoms at different time points (pre-initiation of AI therapy as well as 6-, 12-, and 18-months post-initiation of AI therapy) among two cohorts: patients with breast cancer (n = 250) and healthy controls (n = 130). The researchers used the Brief Pain Inventory score to measure pain and the Breast Cancer Prevention Trial Symptom Inventory and Musculoskeletal Subscale to measure musculoskeletal symptoms.

Going further, Dr Zhu and colleagues also genotyped 46 candidate single nucleotide polymorphisms (SNPs) among those who provided their DNA (n = 243). The researchers performed group-based trajectory modeling at 18 months for pain and musculoskeletal symptoms, and they assessed multivariate multinomial logistic regression models to determine demographic, clinical, and genetic factors.

Dr Zhu and colleagues found that a majority of the study participants experienced mild (45.1%) or moderate pain (20.7%) and musculoskeletal symptoms (mild 39.7%, moderate 10.5%, respectively) in a persistent or consistently increasing manner over the first 18 months of AI therapy.

The researchers also analyzed the profile of certain protective and risk factors across pain and musculoskeletal symptoms. Among the assessed phenotypes, the protective factors included:

•         older age
•         receiving chemotherapy
•         having an older first menstrual period age
•         being married/partnered
•         having an administrative level of occupation
•         having a regular period for most of life
•         having greater numbers of pregnancies
•         having a history of tubal ligation

Among the assessed phenotypes, the risk factors included:

•         receiving AI therapy
•         greater anxiety/pain severity/depressive symptoms/fatigue at baseline
•         having history of arthritis, hysterectomy, or menopausal symptoms

Looking into the genotyped SNPs, researchers found that variations in CYP19A1 (rs1008805) and NOS3 (rs1799983) were associated with pain and musculoskeletal symptoms as well.

“Our results support the longitudinal inter-individual variability in musculoskeletal pain with AI therapy for breast cancer,” the authors concluded.