Bone safety profile of steroidal aromatase inhibitor in comparison to non-steroidal aromatase inhibitors in postmenopausal women with breast cancer: A network meta-analysis.

Abstract

527 Background: Steroidal and non-steroidal aromatase inhibitors (AIs) provide better therapeutic response in comparison to other endocrine therapies in the adjuvant treatment of breast cancer (BC). They interfere with bone turnover which may lead to increased incidence of bone related safety events. There are no head-on studies comparing the incidence of bone safety events and hence we performed this network meta-analysis (NMA) to compare the incidence of bone safety events among patients treated with steroidal and non-steroidal AIs. Methods: Literature searches were performed in PubMed and Embase with key words to identify randomized controlled trials in BC patients treated with AIs in adjuvant settings compared against tamoxifen or other AIs, reporting any bone-related safety events. The study was designed as per PRISMA guidelines; publication bias was evaluated by comparison-adjusted funnel plots. Bayesian NMA was done by R software (ver 3.2), GemtC package. Odds ratio (OR) and the surface under the cumulative ranking curve (SUCRA) values were used to interpret the results. Results: 15 studies reporting 6 different bone-related endpoints were included. Treatment with steroidal AI, exemestane led to lower incidence of bone pain (OR Vs anastrozole and letrozole: 0.59, p=0.63; 0.54, p=0.75), fracture episodes (OR Vs anastrozole and letrozole: 0.84, p=0.41; 0.85, p=0.73), joint stiffness (OR Vs anastrozole: 0.55, p=0.73) and osteoporosis (OR Vs anastrozole and letrozole: 0.86, p=0.41; 0.74, p=0.29) (Table) in comparison to letrozole and anastrozole. Reduction in bone mineral density was also lesser in exemestane than anastrozole (mean reduction in hip: 1.08; lumbar spine: 1.34). SUCRA values suggested exemestane to be the drug with maximum likelihood for reducing the incidence of bone-related adverse events. Conclusions: This NMA suggested that bone-related safety events might be lower in early BC patients treated with exemestane in comparison to non-steroidal AIs, anastrozole and letrozole. Although there was no statistical significance, further head-on studies are required to substantiate our results.[Table: see text]