Table 1.

Summary of the exclusion reasons for all three eligibility evaluation steps

Reason for exclusion	Number
Abstracts/Comments/Letters	60
Metastatic focus	17
Dubious article/Language/Not found	45
Different method/Goal	162
No performance data	54
Too specific subtype of BC	11
Unclear stage data	33
> 4,5% stage IV samples	31
Review/Meta-analysis	86
Prognostic	68
Not related to BC	3
Exosomal miRNAs	23
Therapeutic	47
Not biomarker focused	26
Total excluded publications	666