title: Early volume variation of positive lymph nodes assessed by in-room mega voltage CT images predicts risk of loco-regional relapses in head and neck cancer patients treated with intensity-modulated radiotherapy.
abstract: BACKGROUND
  We investigated the possibility to early identify non-responding patients based on FDG-PET positive lymph nodes (PNs) volume variation assessed with in-room images.
  
  
  METHODS
  Twenty-seven head and neck cancer patients with at least one pre-treatment PNs were retrospectively analyzed; they received 54 Gy, 66 Gy, 69 Gy in 30 fractions on precautionary lymph nodal (N), primary (T) and PET positive (BTV) planning target volumes (PTVs), respectively with Helical TomoTherapy (SIB approach). PNs volume changes during treatment were assessed based on megavoltage computed tomography (MVCT) used for image guidance as ratio between volumes at fractions 10/20/30 and at first fraction. Data on T, N and M relapses (rT, rN, rM) were collected for all patients. The difference of PNs volume changes, during treatment, between patients with versus without relapses was tested (Mann-Whitney test). The impact of shrinkage on the corresponding survival curves (Cox proportional-hazard regression), dividing between no/moderate versus large shrinkage (based on ROC curve best cut-off value) was also investigated.
  
  
  RESULTS
  Median follow-up was 27.4 m (3.7-108.9). The numbers for rT, rN, rM were 5, 4, 6, respectively. Differences in PNs shrinkage were found between patients with and without rT/rN at all considered timing [fr 20, rT: 0.56 vs. 1.07 (median), p = 0.06; rN: 0.57 vs. 1.25, p = 0.07]. Differences were lower for rM. Survival curves provide high hazard ratios (HR) between PNs changes and rT/rN at all considered timing [fr 20, rT: best cut-off = 0.58, HR 5.1 (95% CI 0.5-49.4), p = 0.12; rN: best cut-off = 0.98, HR 14.9 (1.6-142.9), p = 0.01].
  
  
  CONCLUSIONS
  A limited shrinkage of PNs during treatment is associated with poorer outcome in terms of T/N relapses. The early variation of PNs observed on in-room images may provide useful information about the individual response with potential application in guiding an early adaptation of the treatment.
authors.affiliation: a Medical Physics, S. Raffaele Scientific Institute , Milano , Italy.
authors.forename: Maria Luisa
authors.initials: ML
authors.lastname: Belli
authors.affiliation: a Medical Physics, S. Raffaele Scientific Institute , Milano , Italy.
authors.forename: Claudio
authors.initials: C
authors.lastname: Fiorino
authors.affiliation: b Radiotherapy, S. Raffaele Scientific Institute , Milano , Italy.
authors.forename: Flavia
authors.initials: F
authors.lastname: Zerbetto
authors.affiliation: a Medical Physics, S. Raffaele Scientific Institute , Milano , Italy.
authors.forename: Roberta
authors.initials: R
authors.lastname: Raso
authors.affiliation: a Medical Physics, S. Raffaele Scientific Institute , Milano , Italy.
authors.forename: Sara
authors.initials: S
authors.lastname: Broggi
authors.affiliation: b Radiotherapy, S. Raffaele Scientific Institute , Milano , Italy.
authors.forename: Anna
authors.initials: A
authors.lastname: Chiara
authors.affiliation: a Medical Physics, S. Raffaele Scientific Institute , Milano , Italy.
authors.forename: Giovanni Mauro
authors.initials: GM
authors.lastname: Cattaneo
authors.affiliation: b Radiotherapy, S. Raffaele Scientific Institute , Milano , Italy.
authors.forename: Nadia
authors.initials: N
authors.lastname: Di Muzio
authors.affiliation: b Radiotherapy, S. Raffaele Scientific Institute , Milano , Italy.
authors.forename: Italo
authors.initials: I
authors.lastname: Dell'oca
authors.affiliation: a Medical Physics, S. Raffaele Scientific Institute , Milano , Italy.
authors.forename: Riccardo
authors.initials: R
authors.lastname: Calandrino
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019583:Dose Fractionation, Radiation; D005260:Female; D005500:Follow-Up Studies; D006258:Head and Neck Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D006801:Humans; D008198:Lymph Nodes / Q000000981:diagnostic imaging* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000473:pathology*; D061089:Radiotherapy, Image-Guided; D050397:Radiotherapy, Intensity-Modulated; D012189:Retrospective Studies; D036542:Tomography, Spiral Computed