title: Late term tolerance in head neck cancer patients irradiated in the IMRT era.
abstract: BACKGROUND
  The aim was to quantify severe transient and persisting late term effects in our single institution head neck cancer (HNC) cohort treated with curatively intended intensity modulated radiation therapy (IMRT). Hypothesis was if a 2-year follow up (FU) is sufficient to estimate the long term tolerance in HNC irradiated in the IMRT era.
  
  
  METHODS
  Between 01/2002-8/2012, 707/1211 (58%) consecutively treated IMRT patients met the inclusion criteria of a FU time >12 months and loco-regional disease control (LRC). 45% presented with loco-regionally advanced disease; 55% were referred for curative definitive IMRT (66 Gy-72 Gy in 30-35 fractions), 45% underwent postoperative IMRT (60-66 Gy in 30-33 fractions). Systemic concomitant therapy was administered in 85%. Highly consistent treatment procedures were performed with respect to contouring processes, dose constraints, radiation schedules, and the use of systemic therapy. Grade 3/4 late term effects were prospectively assessed and analyzed with respect to subgroups at particular risk for specific late effects.
  
  
  RESULTS
  Mean/median FU of the cohort was 41/35 months (15-124). 13% of the patients (92/707) experienced any grade 3/4 late effects (101 events in 92/707 patients), 81% in the first 12 months after radiation. 4% of all developed persisting late grade 3/4 effects (25 events in 25/707 patients).
  
  
  CONCLUSIONS
  IMRT led to a high late term tolerance in loco-regionally disease free HNC patients. The onset of any G3/4 effects showed a plateau at 2 years. The question of the cervical vessel tolerance in disease free long time survivors is still open and currently under evaluation at our institution.
authors.affiliation: Department of Radiation Oncology, University Hospital Zurich, Raemistrasse 100, 8091 Zurich, CH, Switzerland. gabriela.studer@usz.ch.
authors.forename: Gabriela
authors.initials: G
authors.lastname: Studer
authors.forename: Claudia
authors.initials: C
authors.lastname: Linsenmeier
authors.forename: Oliver
authors.initials: O
authors.lastname: Riesterer
authors.forename: Yousef
authors.initials: Y
authors.lastname: Najafi
authors.forename: Michelle
authors.initials: M
authors.lastname: Brown
authors.forename: Bita
authors.initials: B
authors.lastname: Yousefi
authors.forename: Marius
authors.initials: M
authors.lastname: Bredell
authors.forename: Gerhard
authors.initials: G
authors.lastname: Huber
authors.forename: Stephan
authors.initials: S
authors.lastname: Schmid
authors.forename: Stephan
authors.initials: S
authors.lastname: Studer
authors.forename: Roger
authors.initials: R
authors.lastname: Zwahlen
authors.forename: Tamara
authors.initials: T
authors.lastname: Rordorf
authors.forename: Christoph
authors.initials: C
authors.lastname: Glanzmann
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000970:Antineoplastic Agents / Q000008:administration & dosage; D015331:Cohort Studies; D018572:Disease-Free Survival; D005260:Female; D005500:Follow-Up Studies; D006258:Head and Neck Neoplasms / Q000188:drug therapy* / Q000401:mortality / Q000532:radiotherapy*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009362:Neoplasm Metastasis; D011446:Prospective Studies; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D012306:Risk; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D000970:Antineoplastic Agents