Breast Cancer Res Treat. 2022 Jun 21. doi: 10.1007/s10549-022-06642-z. Online ahead of print.
PURPOSE: Accumulating evidence has shown that microRNAs (miRNAs) are promising biomarkers of neoadjuvant chemotherapy (NAC) response in breast cancer (BC). However, their predictive roles remain controversial. Thus, this systematic review and meta-analysis aimed to describe the role of miRNA expression in NAC response and prognosis in BC to increase statistical power and improve translation.
METHODS: A systematic review of electronic databases for relevant studies was conducted following PRISMA guidelines. Data were extracted, collated, and combined by odds ratio (OR) and hazard ratio (HR) with 95% confidence intervals (CIs) to estimate the strength of the associations.
RESULTS: Of the 560 articles screened, 59 studies were included in our systematic review, and 5 studies were included in the subsequent meta-analysis. Sixty of 123 miRNAs were found to be related with NAC response and an elevated baseline miR-7 level in tissues was associated with a higher pathological complete response rate (OR 5.63; 95% CI 2.15-14.79; P = 0.0004). The prognostic value of 39 miRNAs was also studied. Of them, 26 miRNAs were found to be associated with survival. Pooled HRs indicated that patients with increased levels of serum miR-21 from baseline to the end of the second NAC cycle and from baseline to the end of NAC had a worse disease-free survival than those with decreased levels.
CONCLUSION: Our results highlight that a large number of miRNAs have possible associations with NAC response and prognosis in BC patients. Further well-designed studies are needed to elucidate the molecular mechanisms underlying these associations.