TY - JOUR
T1 - A dosimetric model of duodenal toxicity after stereotactic body radiotherapy for pancreatic cancer
AU - Murphy, James D.
AU - Christman-Skieller, Claudia
AU - Kim, Jeff
AU - Dieterich, Sonja
AU - Chang, Daniel T.
AU - Koong, Albert C.
PY - 2010/12/1
Y1 - 2010/12/1
N2 - Introduction: Dose escalation for pancreas cancer is limited by the tolerance of adjacent normal tissues, especially with stereotactic body radiotherapy (SBRT). The duodenum is generally considered to be the organ at greatest risk. This study reports on the dosimetric determinants of duodenal toxicity with single-fraction SBRT. Methods and Materials: Seventy-three patients with locally advanced unresectable pancreatic adenocarcinoma received 25 Gy in a single fraction. Dose-volume histogram (DVH) endpoints evaluated include V5 (volume of duodenum that received 5 Gy), V10, V15, V20, V25, and Dmax (maximum dose to 1 cm3). Normal tissue complication probability (NTCP) was evaluated with a Lyman model. Univariate and multivariate analyses were conducted with Kaplan-Meier and Cox regression models. Results: The median time to Grade 2-4 duodenal toxicity was 6.3 months (range, 1.6-11.8 months). The 6- and 12-month actuarial rates of toxicity were 11% and 29%, respectively. V 10-V25 and Dmax all correlated significantly with duodenal toxicity (p < 0.05). In particular, V15 ≥ 9.1 cm3 and V15 < 9.1 cm3 yielded duodenal toxicity rates of 52% and 11%, respectively (p = 0.002); V20 ≥ 3.3 cm3 and V20 < 3.3 cm3 gave toxicity rates of 52% and 11%, respectively (p = 0.002); and Dmax ≥ 23 Gy and Dmax < 23 Gy gave toxicity rates of 49% and 12%, respectively (p = 0.004). Lyman NTCP model optimization generated the coefficients m = 0.23, n = 0.12, and TD50 = 24.6 Gy. Only the Lyman NTCP model remained significant in multivariate analysis (p = 0.001). Conclusions: Multiple DVH endpoints and a Lyman NTCP model are strongly predictive of duodenal toxicity after SBRT for pancreatic cancer. These dose constraints will be valuable in future abdominal SBRT studies.
AB - Introduction: Dose escalation for pancreas cancer is limited by the tolerance of adjacent normal tissues, especially with stereotactic body radiotherapy (SBRT). The duodenum is generally considered to be the organ at greatest risk. This study reports on the dosimetric determinants of duodenal toxicity with single-fraction SBRT. Methods and Materials: Seventy-three patients with locally advanced unresectable pancreatic adenocarcinoma received 25 Gy in a single fraction. Dose-volume histogram (DVH) endpoints evaluated include V5 (volume of duodenum that received 5 Gy), V10, V15, V20, V25, and Dmax (maximum dose to 1 cm3). Normal tissue complication probability (NTCP) was evaluated with a Lyman model. Univariate and multivariate analyses were conducted with Kaplan-Meier and Cox regression models. Results: The median time to Grade 2-4 duodenal toxicity was 6.3 months (range, 1.6-11.8 months). The 6- and 12-month actuarial rates of toxicity were 11% and 29%, respectively. V 10-V25 and Dmax all correlated significantly with duodenal toxicity (p < 0.05). In particular, V15 ≥ 9.1 cm3 and V15 < 9.1 cm3 yielded duodenal toxicity rates of 52% and 11%, respectively (p = 0.002); V20 ≥ 3.3 cm3 and V20 < 3.3 cm3 gave toxicity rates of 52% and 11%, respectively (p = 0.002); and Dmax ≥ 23 Gy and Dmax < 23 Gy gave toxicity rates of 49% and 12%, respectively (p = 0.004). Lyman NTCP model optimization generated the coefficients m = 0.23, n = 0.12, and TD50 = 24.6 Gy. Only the Lyman NTCP model remained significant in multivariate analysis (p = 0.001). Conclusions: Multiple DVH endpoints and a Lyman NTCP model are strongly predictive of duodenal toxicity after SBRT for pancreatic cancer. These dose constraints will be valuable in future abdominal SBRT studies.
KW - Lyman model
KW - NTCP
KW - Pancreas cancer
KW - SBRT
KW - Toxicity
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U2 - 10.1016/j.ijrobp.2009.09.075
DO - 10.1016/j.ijrobp.2009.09.075
M3 - Article
C2 - 20399033
AN - SCOPUS:78549293230
VL - 78
SP - 1420
EP - 1426
JO - International Journal of Radiation Oncology Biology Physics
JF - International Journal of Radiation Oncology Biology Physics
SN - 0360-3016
IS - 5
ER -