title: Seroma indicates increased risk of lymphedema following breast cancer treatment: A retrospective cohort study.
abstract: BACKGROUND
  Lymphedema is one of the most serious complications following breast cancer treatment. While many risk factors are well described the role of seroma formation has recently produced mixed results. Therefore, we aimed to evaluate if seroma is a risk factor for development of lymphedema in one of the largest retrospective cohort studies.
  
  
  METHODS
  We included all patients with unilateral breast cancer treated in the period of 2008-2014. Data regarding treatment and breast cancer characteristics were retrieved from the national breast cancer registry. Data regarding lymphedema treatment and seroma aspirations were retrieved from local treatment codes.
  
  
  RESULTS
  In total 1822 patients were included of which 291 developed lymphedema. Multivariate cox regression analysis showed that seroma was an independent risk factor (HR 1.92 CI 1.30-2.85, p= 0.001). Other independent risk factors were lymphadenectomy, radiation therapy, chemotherapy, BMI above 30, total lymph nodes removed above 15 and higher number of metastatic lymph nodes.
  
  
  CONCLUSIONS
  Postoperative seroma doubles the risk of developing lymphedema. Future studies should examine if seroma reducing measures will lead to lower risk of lymphedema.
authors.affiliation: Department of Plastic Surgery, Odense University Hospital, Denmark. Electronic address: Navid.m.toyserkani@rsyd.dk.
authors.forename: Navid Mohamadpour
authors.initials: NM
authors.lastname: Toyserkani
authors.affiliation: Department of Plastic Surgery, Odense University Hospital, Denmark.
authors.forename: Mads Gustaf
authors.initials: MG
authors.lastname: Jørgensen
authors.affiliation: Breast Surgery Unit, Department of Plastic Surgery, Odense University Hospital, Denmark.
authors.forename: Karen
authors.initials: K
authors.lastname: Haugaard
authors.affiliation: Department of Plastic Surgery, Odense University Hospital, Denmark.
authors.forename: Jens Ahm
authors.initials: JA
authors.lastname: Sørensen
mesh_terms: D000072656:Breast Cancer Lymphedema / Q000209:etiology*; D001943:Breast Neoplasms / Q000473:pathology / Q000601:surgery*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D016015:Logistic Models; D008197:Lymph Node Excision / Q000009:adverse effects; D008198:Lymph Nodes / Q000473:pathology / Q000601:surgery; D008408:Mastectomy / Q000009:adverse effects*; D008875:Middle Aged; D015999:Multivariate Analysis; D011183:Postoperative Complications; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012189:Retrospective Studies; D012307:Risk Factors; D049291:Seroma / Q000209:etiology*
keywords: Breast cancer; Lymphedema; Postoperative complication; Rehabilitation; Seroma