title: Growth patterns of pulmonary metastases: should we adjust resection techniques to primary histology and size?
abstract: OBJECTIVE
  Safety margins in pulmonary metastasectomy are not yet well defined. We hypothesize that histological subtype, size of the lesion and local growth characteristics must be taken into consideration during metastasectomy. This study was conducted to examine and classify growth patterns at resection margins and define the relationships between aggressive local growth, metastasis size and local recurrence to direct metastasectomy.
  
  
  METHODS
  Histologic sections of pulmonary metastases were prospectively collected and haematoxylin-eosin stains were systematically evaluated and classified by their pattern of lung tissue infiltration. Logistic regression was used to model the association between the subgroups of colorectal, renal cell and epithelial cancers and melanomas and sarcomas.
  
  
  RESULTS
  From 183 patients, 412 lung specimens were removed, which contained 459 pulmonary metastases. We found that 58% of all lesions had microscopic signs of aggressive local dissemination. The metastases showed histology-specific patterns of local growth: sarcoma was associated with pleural infiltration; colorectal metastases with interstitial spread and aerogenous spread of floating cancer cell clusters; and melanoma with perivascular growth and with lymph vessel involvement. Aggressive patterns of growth had an increasing probability of around 3% for each additional millimetre of metastasis diameter. Local intrapulmonary recurrence was significantly more common in association with interstitial growth and pleural penetration as well as safety margins <7 mm.
  
  
  CONCLUSIONS
  Approximately 40% of all lung metastases have a smooth surface and might be resected with small margins. Growth characteristics within the lung differ with the histologic subtype and safety margins should generally increase with the size of the metastasis.
authors.affiliation: Department of Thoracic Surgery and Endoscopy, Ruhrlandklinik, West German Lung Center, University Hospital, University of Duisburg-Essen, Essen, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Welter
authors.affiliation: Department of Thoracic Surgery and Endoscopy, Ruhrlandklinik, West German Lung Center, University Hospital, University of Duisburg-Essen, Essen, Germany.
authors.forename: Elias
authors.initials: E
authors.lastname: Arfanis
authors.affiliation: Department of Medical Oncology, West German Cancer Center, University Clinic Essen, University of Duisburg-Essen, Essen, Germany.
authors.forename: Daniel
authors.initials: D
authors.lastname: Christoph
authors.affiliation: Institute of Pathology, University Clinic Essen, University of Duisburg-Essen, Essen, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Hager
authors.affiliation: Department of Thoracic Surgery and Endoscopy, Ruhrlandklinik, West German Lung Center, University Hospital, University of Duisburg-Essen, Essen, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Roesel
authors.affiliation: Department of Thoracic Surgery and Endoscopy, Ruhrlandklinik, West German Lung Center, University Hospital, University of Duisburg-Essen, Essen, Germany.
authors.forename: Clemens
authors.initials: C
authors.lastname: Aigner
authors.affiliation: Department of Pneumology, Ruhrlandklinik, West German Lung Center, University Hospital, University of Duisburg-Essen, Essen, Germany.
authors.forename: Gerhard
authors.initials: G
authors.lastname: Weinreich
authors.affiliation: Institute of Pathology, University Clinic Essen, University of Duisburg-Essen, Essen, Germany.
authors.forename: Dirk
authors.initials: D
authors.lastname: Theegarten
mesh_terms: D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008175:Lung Neoplasms / Q000175:diagnosis / Q000556:secondary*; D008207:Lymphatic Metastasis / Q000473:pathology; D008297:Male; D000072662:Margins of Excision; D059146:Metastasectomy / Q000379:methods*; D009367:Neoplasm Staging; D011446:Prospective Studies; D012189:Retrospective Studies; D012307:Risk Factors
keywords: Growth pattern; Melanoma metastases; Pulmonary metastases; Safety margin