Longitudinal predictor analysis of pain in breast cancer survivors on aromatase inhibitors—the PAC-WOMAN trial

Objective Breast cancer survivors undergoing hormonal therapy with aromatase inhibitors face a significantly increased risk of developing musculoskeletal pain, leading to treatment discontinuation rates of 13% to 22%. Recent literature has focused on identifying and understanding possible risk factors for pain development in breast cancer survivors, not only for pain prevention but also for guiding treatment strategies. This study aimed to investigate predictors of baseline, 4-month, and change scores of pain intensity in breast cancer survivors on aromatase inhibitors. Methods Multiple regression analyses using intent-to-treat data ( N = 110; mean age 56.2 ± 7.7 years) were performed to identify possible predictors applying a biopsychosocial approach with five domains: sociodemographic characteristics, treatment-related factors, health-related factors, physical function factors, and group allocation. The Brief Pain Inventory was used to assess participants' pain intensity. Results Having a partner (95% CI: 0.220, 1.868, p = 0.014), lower sleep quality (95% CI: −1.694, −0.615, p < 0.000), and additional time on the Timed-up-and-go test (95% CI: 0.002, 1.185, p = 0.049) were significant predictors of higher baseline pain intensity. Significant predictors of higher 4-month pain included lower sleep quality (95% CI: −1.095, −0.054, p = 0.031), lower chest press strength (95% CI: −0.231, −0.032, p = 0.010) and being in the brief physical activity counseling group (95% CI: 0.324, 2.155, p = 0.008) relative to the exercise group. In the change scores model, compared to the exercise group, being in the brief physical activity counseling group (95% CI: 0.183, 1.068, p = 0.006), and waitlist control group (95% CI: 0.054, 0.947, p = 0.029) significantly predicted an increase in pain intensity over time. Conversely, having a partner (95% CI: −0.825, −0.057, p = 0.025) significantly predicted a reduction in pain intensity. Conclusions These findings highlight the complex and multifaceted nature of pain in this population and the need for longitudinal studies with diverse populations, as well as advanced methodologies to capture the dynamic nature of pain and refine intervention strategies.