A prospective study of bone loss in early stage postmenopausal breast cancer treated with aromatase inhibitors

Abstract

Objective: To investigate the occurrence and development of aromatase inhibitors (AIs) related bone loss in Chinese patients with postmenopausal early-stage breast cancer. Methods: Patients with estrogen receptor (ER) and (or) progesterone receptor(PR) positive postmenopausal early-stage breast cancer who received Letrozole, Anastrozole, or Exemestane as adjuvant therapy were enrolled. Before treatment, baseline bone mineral density (BMD), bone metabolism markers were examined and a lifestyle questionnaire was completed; BMD was examined annually during the treatment; Outpatient visits were conducted to record recurrent and fatal events. Results: From November 2013 to August 2016, 131 patients with breast cancer eligible for enrollment were enrolled. A total of 65 patients had normal baseline bone mass, and 68 patients had reduced bone mass. Letrozole was taken in 69 patients, anastrozole in 52 patients, and exemestane in 10 patients. With a median follow-up of 43.7 months, 100 patients could be evaluated for changes in bone mineral density. Bone mineral density of femoral neck, total hip, and lumbar spine L1 to 4 decreased year by year, and the decrease was the most significant in the first year, which decreased by 2.3%, 2.4%, and 3.9% respectively. Ten new cases of osteoporosis occurred in two years, eight of them occurred in the lumbar spine, all of whom had reduced bone mass at baseline. Among the 131 patients who completed the lifestyle questionnaire, the proportions of daily calcium supplementation and vitamin D were 28.2% and 7.6%, respectively; more than half (52.7%) of them lacked regular exercise. Conclusion: BMD was declining steadily in patients treated with AIs, especially in the first year. Lumbar spine is the most common osteoporosis site, early prevention and health education should be strengthened.