title: Resection of subsequent pulmonary metastases from treated head and neck squamous cell carcinoma: systematic review and meta-analysis.
abstract: BACKGROUND
  Pulmonary metastasectomy involves the surgical removal of pulmonary nodules. It is a recognised therapeutic modality for the treatment of metastatic disease. There is no consensus as to the role of pulmonary metastasectomy in squamous cell carcinoma of the head and neck. The objective of this study was to determine whether, in selected patients, resection of subsequent pulmonary metastases prolongs survival in patients already treated for head and neck squamous cell carcinoma and to identify independent risk factors that influence 5-year survival of patients undergoing pulmonary metastasectomy.
  
  
  METHODS
  A systematic review of English and non-English articles using MEDLINE (1950-present), EMBASE (1980-present), NHS evidence and Cochrane databases. Search terms included but were not limited to: squamous cell carcinoma, pulmonary metastasectomy or resection, head and neck cancer, malignancy or tumour. Studies examining outcomes for patients with head and neck squamous cell carcinoma who underwent pulmonary metastasectomy for metachronous pulmonary metastases were included. Independent data extraction of articles by two trained researchers using predefined data fields was performed.
  
  
  RESULTS
  Thirteen of 47 studies (all retrospective) fulfilled eligibility criteria, with a total of 403 patients. In total, 11 papers reported 5-year survival rates (Kaplan-Meier) in 387 patients with head and neck squamous cell carcinoma following pulmonary metastasectomy. Meta-analysis of survival data showed an overall absolute 5-year survival rate of 29.1% for patients undergoing pulmonary metastasectomy for metachronous metastases from head and neck squamous cell carcinoma. Two papers reported significantly worse 5-year survival rates in patients with oral head and neck squamous cell carcinoma compared with other sites (9.2% versus 32.4%, P < 0.001 and 15.4% versus 45.2%, P = 0.01). Two papers reported that the presence of cervical lymph node metastases at diagnosis of the primary tumour significantly worsened 5-year survival rates following pulmonary metastasectomy (13.8% (N+) versus 32% (N0) P = 0.01 and 24% (N+) versus 60% (N0) P = 0.025). Other significant poor prognostic factors included incomplete pulmonary resection and the presence of multiple pulmonary nodules.
  
  
  CONCLUSIONS
  This systematic review provides level 2a evidence of the effectiveness of pulmonary metastasectomy for metachronous pulmonary metastases from head and neck squamous carcinoma, which may offer prolonged survival for selected patients. Poor prognostic factors for pulmonary metastasectomy in this cohort of patients include the presence of lymph node metastasis at the diagnosis of the original tumour, squamous cell carcinoma of the oral cavity, incomplete pulmonary resection and the presence of multiple pulmonary nodules.
authors.affiliation: Institute of Head and Neck Studies and Education, School of Cancer Sciences, University of Birmingham, Birmingham, UK.
authors.forename: E R
authors.initials: ER
authors.lastname: Young
authors.affiliation: Institute of Head and Neck Studies and Education, School of Cancer Sciences, University of Birmingham, Birmingham, UK.
authors.forename: E
authors.initials: E
authors.lastname: Diakos
authors.affiliation: Institute of Head and Neck Studies and Education, School of Cancer Sciences, University of Birmingham, Birmingham, UK.
authors.forename: M
authors.initials: M
authors.lastname: Khalid-Raja
authors.affiliation: Institute of Head and Neck Studies and Education, School of Cancer Sciences, University of Birmingham, Birmingham, UK.
authors.forename: H
authors.initials: H
authors.lastname: Mehanna
mesh_terms: D002294:Carcinoma, Squamous Cell / Q000175:diagnosis / Q000556:secondary / Q000601:surgery; D006258:Head and Neck Neoplasms / Q000175:diagnosis / Q000556:secondary / Q000601:surgery; D006801:Humans; D008175:Lung Neoplasms / Q000175:diagnosis / Q000556:secondary / Q000601:surgery; D059146:Metastasectomy / Q000379:methods*; D011013:Pneumonectomy / Q000379:methods*; D000077195:Squamous Cell Carcinoma of Head and Neck