title: Tumour seeding in the surgical pathway after resection of skull base chordoma.
abstract: OBJECTIVE
  The aim of this study is to review the clinical series in which tumour seeding was reported after skull base surgery for chordomas.
  
  
  BACKGROUND
  The occurrence of implantation of cancer cells during surgical procedures for the removal of chordoma is a rare event described by a number of authors in a few patient series and case reports.
  
  
  METHODS
  Literature search was performed by PubMed and Scopus by using the words "surgical tumour seeding, tumour implantation, surgical pathway recurrence, skull base chordoma, and clivus chordoma".
  
  
  RESULTS
  Six retrospective series and 7 case reports were included in the analysis. In total, 34 patients are described with pathway recurrence, 30 at a single site and 4 at multiple sites. In the 5 largest chordoma series, the rate of occurrence of surgical seeding ranged from 1.3% to 7.3% (3.9%). In the 34 patients diagnosed with tumour seeding, the most frequent surgical approach was trans-nasal/trans-sphenoidal, that was used in 12 cases. The median time from primary treatment to surgical pathway tumour seeding ranged from 7 to 78 months. Data of the treatment of seeding are available in 26/34 patients. All of them underwent a new surgery, 6 received additional external beam radiotherapy, and 2 intraoperative radiotherapy.
  
  
  CONCLUSIONS
  The risk of surgical seeding should be taken into consideration when deciding on the surgical approach and the planning treatment volume for postoperative radiation therapy. The surgical pathway should be included in follow-up studies to diagnose this peculiar type of treatment failure possibly at an early phase.
authors.affiliation: Division of Radiotherapy, University Hospital "Maggiore della Carità", Novara, Italy; Department of Translational Medicine, University of "Piemonte Orientale", Novara, Italy; Centro Nazionale Adroterapia Oncologica (CNAO), Pavia, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Krengli
authors.affiliation: Department of Otorhinolaryngology, Humanitas Research Hospital, Rozzano, Milan, Italy.
authors.forename: Arturo
authors.initials: A
authors.lastname: Poletti
authors.affiliation: Division of Radiotherapy, University Hospital "Maggiore della Carità", Novara, Italy; Department of Translational Medicine, University of "Piemonte Orientale", Novara, Italy.
authors.forename: Eleonora
authors.initials: E
authors.lastname: Ferrara
authors.affiliation: Centro Nazionale Adroterapia Oncologica (CNAO), Pavia, Italy; Department of Radiotherapy, Istituto Europeo di Oncologia (IEO), Milan, Italy.
authors.forename: Piero
authors.initials: P
authors.lastname: Fossati
keywords: Skull base chordoma; Surgery; Surgical pathway recurrence; Tumour seeding