title: SPECT/CT lymphoscintigraphy of sentinel node(s) for superselective prophylactic irradiation of the neck in cN0 head and neck cancer patients: a prospective phase I feasibility study.
abstract: BACKGROUND
  Clinically node negative HNSCC patients have a risk ranging between 18 and 45% of occult metastases, making prophylactic irradiation mandatory. Selective irradiation of nodal target volume based on international guidelines is practice. Anyway, about half the tumours lying in an anatomical subsite known to potentially drain bilaterally effectively do so, leading to unnecessary large volume irradiation. Moreover, 15% of the tumours show drainage outside of predicted basin, increasing the risk for potential geographical misses. Three-dimensional SPECT/CT lymphoscintigraphy (LS) of sentinel node(s) may help to individualize nodal target volume selection. This prospective phase I study explores its feasibility and the dosimetric impact.
  
  
  METHODS
  Ten cN0 HNSCC patients eligible for definitive radiotherapy were imaged with SPECT/CT after 99mTc nanocolloid injection around the tumour. The neck levels containing up to four hottest nodes were identified and selected for prophylactic irradiation (CTVn-LS) by volumetric modulated arc therapy. A comparative virtual planning was performed with volumes selected according to international guidelines (CTVn-IG).
  
  
  RESULTS
  Migration was observed in all patients (one with gamma probe only). 2.9 sentinel nodes were detected per patient on average. In some patients, accurate localization was difficult when not using thermoplastic mask for SPECT/CT. CTVn-LS was totally encompassed by CTVn-IG in all patients but one (unpredicted drainage in retropharyngeal level). On average, CTVn-LS and related planning target volumes were two times smaller than IG ones. This led to significant dose decrease in identified organs at risk as well as remaining volume at risk.
  
  
  CONCLUSIONS
  SPECT/CT LS is a promising tool to individualize prophylactic node CTV in cN0 HNSCC patients eligible for definitive radiotherapy. Oncological safety must be confirmed by ongoing phase II study.
authors.affiliation: Radiation Oncology, Clinique & Maternité Ste-Elisabeth, Place Louise Godin, Namur 15 - 5000, Belgium. jeanfrancois.daisne@cmsenamur.be.
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Daisne
authors.forename: Johanne
authors.initials: J
authors.lastname: Installé
authors.forename: Benoît
authors.initials: B
authors.lastname: Bihin
authors.forename: Marc
authors.initials: M
authors.lastname: Laloux
authors.forename: Thierry
authors.initials: T
authors.lastname: Vander Borght
authors.forename: Isabelle
authors.initials: I
authors.lastname: Mathieu
authors.forename: Georges
authors.initials: G
authors.lastname: Lawson
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005240:Feasibility Studies; D005260:Female; D005500:Follow-Up Studies; D006258:Head and Neck Neoplasms / Q000473:pathology* / Q000532:radiotherapy*; D006801:Humans; D008198:Lymph Nodes / Q000473:pathology*; D061305:Lymphoscintigraphy; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D011379:Prognosis; D011446:Prospective Studies; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D050397:Radiotherapy, Intensity-Modulated; D021701:Sentinel Lymph Node Biopsy; D015899:Tomography, Emission-Computed, Single-Photon