Factors associated with bone metastasis in breast cancer: a systematic review and meta-analysis.

BACKGROUND To systematically evaluate and analyze the risk factors for breast cancer (BC) with bone metastasis (BM) and provide clinical evidence supporting the early prevention of BM. METHODS We systematically retrieved databases from the Cochrane Library, PubMed, Web of Science, and EMBASE for BC with BM patient. Limited: publish cation between January 1, 2001, and December 31, 2019. Literature screening and evaluation were performed independently by 2 evaluators. The quality of all included studies was evaluated with the NOS. Studies with NOS ≥6 on factors related to the BM of BC were identified. Weighted odds ratio (OR) were used as the combined effects. RESULTS We identified 18 articles with available data. The NOS scores ranged from 6-9. Progesterone receptor (PR)-positive BC patients had a relatively lower risk of BM [I2=45.9%, OR =0.80, 95% confidence interval (CI): 0.72, 0.88, P<0.001]. HER2-positive BC patients had a relatively higher risk of BM (I2=77.6%, OR =1.35, 95% CI: 1.04, 1.76, P=0.025). The risk of BM in patients with lymph node metastasis was higher than that in patients with no lymph node metastasis (I2=99.7%, OR =2.60, 95% CI: 1.41, 4.80, P=0.002). The risk of BM in stage T2 BC patients was 1.99 times that in stage T1 BC patients (I2=96.8%, OR =1.99, 95% CI: 1.03, 3.83, P=0.040). The risk of BM in stage T3 BC patients was 4.74 times that in stage T1 BC patients (I2=95.6%, OR =4.74, 95% CI: 1.94, 11.57, P=0.001). The risk of BM in stage T4 BC patients was 14.57 times that in stage T1 BC patients (I2=95.4%, OR =14.57, 95% CI: 4.16, 51.05, P<0.001). The incidence of BM in BC patients without lobular or ductal BC was significantly higher than that in patients with ductal BC (I2=56.4%, OR =1.26, 95% CI: 1.09, 1.45, P=0.001). DISCUSSION Patients with PR-positive BC have a relatively lower risk of BM. Patients with HER2-positive, lymph node metastasis-positive, nonlobular, or ductal BC have a relatively higher risk of BM. With increasing T stage, the risk of BM in BC patients also increases.