Pain sensitivity and aromatase inhibitor (AI)-associated arthralgias (AIAA).

9615 Background: AIAA affect up to half of AI-treated women with early stage breast cancer, and can lead to treatment discontinuation in 20-30%. The etiology is thought to be related to estrogen deprivation although the mechanism is unknown. In premenopausal women, lower estrogen levels have been associated with increased pain. Impaired descending pain inhibitory pathways, which may be a risk factor for developing chronic pain, have also been associated with lower estrogen levels. We prospectively tested whether AI-induced estrogen deprivation alters pain sensitivity, thereby increasing the risk of developing AIAA. Methods: Fifty postmenopausal women with early stage breast cancer initiating AI therapy were enrolled to the study. Subjects underwent experimental pressure pain testing and conditioned pain modulation (CPM) assessment and completed symptom questionnaires prior to AI initiation and after 3 months. Positive CPM values (>0) signify impaired descending pain inhibition. Serum estradiol concentrati...