title: Results of photon radiotherapy for unresectable salivary gland tumors: is neutron radiotherapy's local control superior?
abstract: BACKGROUND
  The results of RTOG-MRC randomized trial of photon (n=15) versus neutron (n=17) therapy in the 1980's reported an improved local control (LC) with neutron radiotherapy for unresectable salivary gland tumors. Due to increased severe toxicity with neutron radiotherapy and the paucity of neutron-therapy centers, we analyzed our institution's results of photon radiotherapy for unresectable salivary gland tumors.
  
  
  METHODS
  From 1990 to 2009, 27 patients with unresectable salivary gland cancer underwent definitive photon radiotherapy at our institution. Nodal involvement on presentation was found in 9 patients. Median dose of radiotherapy was 70 Gy. Chemotherapy was given to 18 patients, most being platinum-based regimens. Local control (LC), locoregional control (LRC), distant metastasis-free survival (DMFS), overall survival (OS), and toxicity outcomes were assessed.
  
  
  RESULTS
  With a median follow-up of 52.4 months, the 2/5-year actuarial LC was 69% (95%CI ± 21.0%)/55% (± 24.2%), LRC was 65% (± 21.4%)/47% (± 21.6%), and DMFS was 71% (± 21.8%)/51% (± 22.8%), respectively using competing risk analysis. The median OS was 25.7 months, and the 2/5-year OS rates were 50% (± 19.0%)/29% (± 16.6%), respectively. Higher histologic grade was significant for an increased rate of DM (intermediate grade vs. low grade, p=0.04, HR 7.93; high grade vs. low grade, p=0.01, HR 13.50). Thirteen (48%) patient's experienced acute grade 3 toxicity. Late grade 3 toxicity occurred in three (11%) patients.
  
  
  CONCLUSIONS
  Our data compares favorably to neutron radiotherapy with fewer late complications. Photon radiotherapy is an acceptable alternative to neutron radiotherapy in patients who present with unresectable salivary gland tumors.
authors.affiliation: Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, NY, USA.
authors.forename: Daniel E
authors.initials: DE
authors.lastname: Spratt
authors.affiliation: Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, NY, USA.
authors.forename: Lucas Resende
authors.initials: LR
authors.lastname: Salgado
authors.affiliation: Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, NY, USA.
authors.forename: Nadeem
authors.initials: N
authors.lastname: Riaz
authors.affiliation: Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, NY, USA.
authors.forename: Michael G
authors.initials: MG
authors.lastname: Doran
authors.affiliation: Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, NY, USA.
authors.forename: Moses
authors.initials: M
authors.lastname: Tam
authors.affiliation: Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, NY, USA.
authors.forename: Suzanne
authors.initials: S
authors.lastname: Wolden
authors.affiliation: Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, NY, USA.
authors.forename: Evangelia
authors.initials: E
authors.lastname: Katsoulakis
authors.affiliation: Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, NY, USA.
authors.forename: Shyam
authors.initials: S
authors.lastname: Rao
authors.affiliation: Department of Medicine, Memorial Sloan-Kettering Cancer Center, New York, NY, USA.
authors.forename: Alan
authors.initials: A
authors.lastname: Ho
authors.affiliation: Department of Head and Neck Surgery, Memorial Sloan-Kettering Cancer Center, New York, NY, USA.
authors.forename: Richard
authors.initials: R
authors.lastname: Wong
authors.affiliation: Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, NY, USA.
authors.forename: Nancy Y
authors.initials: NY
authors.lastname: Lee
keywords: IMRT; neutron; photon; radiotherapy; salivary gland cancer