No abstract

Conformal radiation therapy (RT) delivered concomitantly with chemotherapy including 5-fluorouracil (5-FU) or Gemcitabine (GEM) is a common treatment for patients with unresectable locally advanced pancreatic tumors. In this study, the Poisson model describing tumor response to these two treatment options was derived. Clinical data was retrieved from reports published from 1990 to 2015. Dosimetric and clinical data from 1196 patients treated with RT with concurrent 5-FU or GEM were gathered. RT doses ranging from 3.6-64.8 Gy, delivered in fractions of 1.2-8 Gy, were converted to a 2 Gy fractionation scheme using the Biological Effective Dose concept. The parameters of the Poisson-Linear-Quadratic-Time model were derived using genetic algorithm optimization to minimize the least-square fitting error. The goodness of the fit was assessed using the Pearson χ 2 -test. For RT+5-FU, D50 was 56.5 Gy, γ was 3, /β was 4.4, Tpot was 36 days and Tk was 23 days. For RT+GEM, D50 was 48.3 Gy, γ was 3, /β was 6.4, Tpot was 36 days and Tk was 23 days. As expected, RT+GEM showed higher efficacy than RT+5-FU. A RT dose-response effect was obtained showing that treatment strategies allowing a dose-escalation in pancreas tumors should be investigated.