A prospective study of aromatase inhibitor therapy, vitamin D, C-reactive protein and musculoskeletal symptoms.

This study compared type, severity and location of musculoskeletal symptoms and associations with 25-hydroxyvitamin D (25(OH)D) and C-reactive protein (CRP) concentrations between women initiating aromatase inhibitor (AI) therapy and an unexposed comparison group. A 6-month prospective cohort study was conducted, enrolling 100 breast cancer patients prior to initiating AI treatment and an unexposed comparison group of 200 postmenopausal women. Multivariate associations were assessed with generalized linear models. At baseline, 55% of breast cancer patients and 63% of the comparison group reported any musculoskeletal symptoms. Among the unexposed group, prevalence and severity of symptoms remained constant with no statistically significant change over 6 months. Among breast cancer patients, but not unexposed women, the pain severity score significantly increased over the 6 month period for joint (P (trend) < 0.001), muscle (P (trend) = 0.004), and bone pain (P (trend) = 0.01). Women treated with AIs were more likely to report pain in wrists/palms (63% at 6 months) compared to unexposed women (31% at 6 months) (P < 0.001). 25(OH)D concentrations increased over the study period among breast cancer patients (P (trend) = 0.004). An increase in pain severity and prevalence was observed among breast cancer patients despite an increase in 25 (OH)D concentration. CRP concentrations were not associated with symptoms. Musculoskeletal symptoms are common among postmenopausal women. Breast cancer patients initiating AI treatment were at increased risk for developing new onset and more severe joint, muscle and bone pain compared to unexposed women, with a distinct distribution. AI-associated symptoms were not associated with 25(OH)D or CRP concentrations.