Prognosis and clinicopathological characteristics of metaplastic breast cancer: A meta-analysis

To compare the clinicopathological characteristics and prognosis of metaplastic breast cancer (MBC) and triple-negative breast cancer (TNBC).

A meta-analysis was performed on relevant cohort or case-control studies retrieved by a literature search of the PubMed, EMBASE, Ovid, and Web of Science databases. Hazard ratio (HR) was used to evaluate disease-free survival (DFS) and overall survival (OS), and the odds ratio (OR) and corresponding 95% confidence interval (CI) was used to evaluate clinicopathological characteristics, including age, tumor diameter, lymph node metastasis status, distant metastasis status, TNM staging, and histological grade.

Nine studies were included in the meta-analysis. Compared with TNBC patients, the HRs for 5-year DFS and 5-year OS of those with MBC were 1.64 (95% confidence interval [CI] 1.36 - 1.98; P < .001) and 1.52 (95% CI 1.27 - 1.81; P < .001), respectively. The OR for age ≥ 50 years, tumor diameter ≤ 5 cm, lymph node-negative, distant metastasis, TNM stage III and IV, and histological grade 3 was 1.63 (95% CI 1.45-1.84), 0.29 (95% CI 0.14-0.58), 1.46 (95% CI 1.13-1.88), 1.59 (95% CI 0.89-2.81), 1.49 (95% CI 0.80-2.77), and 2.25 (95% CI 0.85-5.97), respectively.

Patients with MBC had worse prognosis than those with TNBC. Furthermore, regarding clinicopathological characteristics, patients with MBC mostly presented at ≥ 50 years of age, with tumor diameter > 5 cm, and negative lymph nodes at first diagnosis. Moreover, there were no statistically significant differences in the occurrence of distant metastasis, TNM stages III and IV, or histological grade 3. MBC treatment was not assessed in this study. Data from randomized controlled trials are needed to guide the treatment of patients with MBC.