title: Metastasis to a percutaneous gastrostomy site from head and neck cancer: radiobiologic considerations.
abstract: BACKGROUND
  The use of percutaneously placed feeding tubes has increased in recent years in an effort to maintain adequate caloric balance in patients receiving combined therapy for head and neck cancers, particularly concurrent radiotherapy and chemotherapy.
  
  
  METHODS
  We report a case of a metastasis to a percutaneous endoscopic gastrostomy site occurring in a patient with an advanced tonsillar squamous cell carcinoma and review the published literature regarding this subject. Radiobiologic principles were examined to explain the most likely cause of such metastases.
  
  
  RESULTS
  Six cases of percutaneous endoscopic site metastases occurring in patients with head and neck primary tumors have been reported in the literature. The interval from performance of the procedure to development of the metastases ranged from 3 to 16 months. Tumor kinetics suggest that a significant tumor burden (10(5)-10(6) cells) would need to be present at the site to manifest a metastatic lesion in such a short time interval.
  
  
  CONCLUSIONS
  The development of metastases at percutaneous endoscopic gastrostomy sites is a relatively uncommon occurrence. Direct tumor implantation by means of instrumentation at the time of the procedure is most likely explanation for such metastases, although hematogenous seeding cannot be completely discounted. Techniques should be used so as not to disrupt the tumor bed, particularly when gross residual disease is present.
authors.affiliation: Department of Radiation Oncology, University of Washington Medical Center, 1959 N. E. Pacific St., Box 356043, Seattle, Washington 98195-6043, USA.
authors.forename: J G
authors.initials: JG
authors.lastname: Douglas
authors.forename: W
authors.initials: W
authors.lastname: Koh
authors.forename: G E
authors.initials: GE
authors.lastname: Laramore
mesh_terms: D000234:Adenoids / Q000473:pathology; D001707:Biopsy, Needle; D002294:Carcinoma, Squamous Cell / Q000532:radiotherapy / Q000556:secondary*; D002408:Catheters, Indwelling / Q000009:adverse effects*; D017809:Fatal Outcome; D005774:Gastrostomy / Q000009:adverse effects*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009366:Neoplasm Seeding; D010610:Pharyngeal Neoplasms / Q000473:pathology* / Q000532:radiotherapy; D012878:Skin Neoplasms / Q000175:diagnosis / Q000532:radiotherapy / Q000556:secondary*