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Int J Radiat Oncol Biol Phys. 2011 Mar 1;79(3):901-8. doi: 10.1016/j.ijrobp.2010.04.050. Epub 2010 Aug 12.

Potential of adaptive radiotherapy to escalate the radiation dose in combined radiochemotherapy for locally advanced non-small cell lung cancer.

Author information

1
Department of Radiation Oncology, University of Wuerzburg, Wuerzburg, Germany. guckenberger_m@klinik.uni-wuerzburg.de

Abstract

PURPOSE:

To evaluate the potential of adaptive radiotherapy (ART) for advanced-stage non-small cell lung cancer (NSCLC) in terms of lung sparing and dose escalation.

METHODS AND MATERIALS:

In 13 patients with locally advanced NSCLC, weekly CT images were acquired during radio- (n=1) or radiochemotherapy (n=12) for simulation of ART. Three-dimensional (3D) conformal treatment plans were generated: conventionally fractionated doses of 66 Gy were prescribed to the planning target volume without elective lymph node irradiation (Plan_3D). Using a surface-based algorithm of deformable image registration, accumulated doses were calculated in the CT images acquired during the treatment course (Plan_4D). Field sizes were adapted to tumor shrinkage once in week 3 or 5 and twice in weeks 3 and 5.

RESULTS:

A continuous tumor regression of 1.2% per day resulted in a residual gross tumor volume (GTV) of 49%±15% after six weeks of treatment. No systematic differences between Plan_3D and Plan_4D were observed regarding doses to the GTV, lung, and spinal cord. Plan adaptation to tumor shrinkage resulted in significantly decreased lung doses without compromising GTV coverage: single-plan adaptation in Week 3 or 5 and twice-plan adaptation in Weeks 3 and 5 reduced the mean lung dose by 5.0%±4.4%, 5.6%±2.9% and 7.9%±4.8%, respectively. This lung sparing with twice ART allowed an iso-mean lung dose escalation of the GTV dose from 66.8 Gy±0.8 Gy to 73.6 Gy±3.8 Gy.

CONCLUSIONS:

Adaptation of radiotherapy to continuous tumor shrinkage during the treatment course reduced doses to the lung, allowed significant dose escalation and has the potential of increased local control.

PMID:
20708850
DOI:
10.1016/j.ijrobp.2010.04.050
[Indexed for MEDLINE]

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