Factors Associated with Anastrozole‐Induced Musculoskeletal Adverse Effects in Post‐menopausal Breast Cancer Women: A Preliminary Report

Abstract

Anastrozole (Anas) is one of the drugs of choice in the treatment of estrogen‐receptor (ER) positive post‐menopausal (PM) breast cancer patients. However, Anas‐associated musculoskeletal adverse effects (MAE) (joint pain/stiffness and bone pain) are common and can lead to withdrawal of many patients from treatment. This is a cross‐sectional study of ER PM Women (n=35) with stage I to IV breast cancer receiving Anas. Simple logistic regression analyses were conducted to examine the associations between MAE and tumour grade, progesterone receptor (PR) and human epidermal growth factor (HER2) status, age at menarche, age at menopause and years since menopause, history of contraceptives use and duration of Anas administration. Women with grade I tumours and less than 5 years of menopause tend to have lower odds of MAE [odds ratio (OR) 0.75, confidence interval (CI) 0.08 to 6.71, p =0.797; and OR 0.83, CI 0.09 to 7.68, p =0.87 respectively]. PR and HER2 positive women had a tendency for higher odds of MAE (OR 1.33, CI 0.23 to 7.80, p =0.750 and OR 1.60, CI 0.39 to 6.62, p= 0.517 respectively). Similarly, women with history of contraceptive use and less than 3 years of use of Anas tend to have higher odds of having MAE (OR 1.93, CI 0.43 to 8.61, p = 0.391 and OR 1.13, CI 0.06 to 21.09, p=0.006 respectively). The present study shows that tumour grade, host hormonal environment, duration of Anas treatment and past history of contraceptive use may contribute to the pathophysiology of MAE. However, our findings require further confirmation by using larger sample size and conducting multivariable analyses.