title: Palliative two-dimensional radiotherapy of pancreatic carcinoma: a feasibility study.
abstract: OBJECTIVE
  The aim of the study was to analyze the dose to be administered with two-dimensional involved-field palliative radiotherapy in advanced pancreatic carcinoma with respect to current dose-volume constraints (QUANTEC).
  
  
  METHODS
  The following standard regimens were evaluated: 30 Gy at 3 Gy/fraction (regimen A), 36 Gy at 2.4 Gy/fraction (regimen B), 45 Gy at 1.8 Gy/fraction (regimen C), and 50 Gy at 2 Gy /fraction (regimen D). The following constraints were considered: spinal cord Dmax <50 Gy, duodenum Dmax <55 Gy, liver Dmean <30 Gy, kidneys Dmean <15 Gy. For dose/fraction different from 1.8-2 Gy, the correction of constraints using a value of alpha/beta = 3 for late effects was considered. The calculation of dose/volume constraints was repeated for three different radiation beams: cobalt unit, 6 MV photons, and 15 MV photons. Standard field sizes were used and adapted according to the different beam types, using the parameters of our previous study. Respect of dose-volume constraints was assessed for each type of beam and treatment (dose per fractionation) in all patients. Treatments were considered acceptable in case of: 1) respect of the constraints for spinal cord and duodenum in all patients; 2) respect in >10/15 patients of constraints for kidneys and liver. Therefore, minor violations (<10%) of the constraints for these organs were accepted (in less than 5/15 patients), in consideration of the palliative aim of treatment.
  
  
  RESULTS
  In regimen A (30 Gy, 3 Gy/fraction), evaluated constraints were respected in all patients, regardless of the type of energy. In regimen B (36 Gy, 2.4 Gy/fraction), constraints were met in all patients undergoing irradiation with 6 and 15 MV photons. However, using the cobalt unit, kidney constraint was respected only in 5 of 15 patients. In regimens C and D (45 Gy, 1.8 Gy/fraction and 50 Gy, 2 Gy/fraction, respectively), the constraint for the kidney was respected only in 2-5 patients, depending on the energy used. Furthermore, using 50 Gy, the spinal cord constraint was not respected in 2-3 patients, depending on the beam used. Therefore, only the following treatments were considered acceptable: 1) 30 Gy, 3 Gy/fraction, regardless of the energy used; 2) 36 Gy, 2.4 Gy/fraction, only for treatments performed with linear accelerator (6-15 MV).
  
  
  CONCLUSIONS
  The clinical benefits of radiotherapy in pancreatic tumors should not be withheld from patients treated in centers only with two-dimensional technology. Prospective trials, particularly in developing countries, would be useful to evaluate the efficacy in this setting of involved-field two-dimensional treatments using the dose and fractionation defined in this analysis.
authors: Alessio G
authors: AG
authors: Morganti
authors: Alfonso
authors: A
authors: Marinelli
authors: Milly
authors: M
authors: Buwenge
authors: Gabriella
authors: G
authors: Macchia
authors: Francesco
authors: F
authors: Deodato
authors: Mariangela
authors: M
authors: Massaccesi
authors: Joseph
authors: J
authors: Kigula-Mugambe
authors: Tigeneh
authors: T
authors: Wondemagegnhu
authors: David
authors: D
authors: Dawotola
authors: Luciana
authors: L
authors: Caravatta
authors: Giuseppina
authors: G
authors: Sallustio
authors: Angelo
authors: A
authors: Piermattei
authors: Vincenzo
authors: V
authors: Valentini
authors: Savino
authors: S
authors: Cilla
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002277:Carcinoma / Q000532:radiotherapy*; D019583:Dose Fractionation, Radiation; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010166:Palliative Care / Q000379:methods*; D010190:Pancreatic Neoplasms / Q000532:radiotherapy*; D011880:Radiotherapy Planning, Computer-Assisted; D011881:Radiotherapy, Computer-Assisted