title: A meta-analysis of internal mammary lymph node metastasis in breast cancer patients.
abstract: BACKGROUND
  Knowing the status of the internal mammary lymph (IML) nodes is important for accurate staging and appropriate selection of subsequent treatment in breast cancer. We conducted a meta-analysis to clarify the rate of IML node metastasis in breast cancer patients and discussed the importance of this finding.
  
  
  METHODS
  We retrieved articles from the literature that reported positive rates of IML node metastasis in breast cancer patients. The quality of the selected articles was assessed using the 'Methodological Index for Non-Randomized Studies'. The heterogeneity was tested, and publication bias was assessed using a funnel plot. Finally, the positive rate of IML node metastasis in breast cancer patients was calculated using the random-effects model.
  
  
  RESULTS
  15 articles met the inclusion criteria and a total of 4,248 patients were included in the analysis. Heterogeneity across the studies was statistically significant (p = 0.014); thus, the random-effects model was used and the calculated positive rate of IML node metastasis was 23% (95% confidence interval (CI), 0.21-0.25).
  
  
  CONCLUSIONS
  Approximately 23% of the breast cancer patients had IML node metastases, for which the prognosis is generally poor. Accurate staging and integrated treatment are necessary to improve the survival of these patients.
authors.affiliation: Tangshan Gongren Hospital, Lunan District, Tangshan, China.
authors.forename: Zongtao
authors.initials: Z
authors.lastname: Li
authors.forename: Xiaomei
authors.initials: X
authors.lastname: Gu
authors.forename: Junwang
authors.initials: J
authors.lastname: Tong
authors.forename: Bingli
authors.initials: B
authors.lastname: Liu
authors.forename: Liqian
authors.initials: L
authors.lastname: Sun
authors.forename: Xiaozeng
authors.initials: X
authors.lastname: Gao
authors.forename: Xiaohua
authors.initials: X
authors.lastname: Jiang
mesh_terms: D001943:Breast Neoplasms / Q000401:mortality* / Q000473:pathology*; D002277:Carcinoma / Q000401:mortality* / Q000473:pathology / Q000556:secondary*; D005260:Female; D006801:Humans; D015994:Incidence; D008198:Lymph Nodes / Q000473:pathology*; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012307:Risk Factors; D012680:Sensitivity and Specificity; D021701:Sentinel Lymph Node Biopsy / Q000706:statistics & numerical data*; D015996:Survival Rate