Radiation Dose Prescription for Non-Small-Cell Lung Cancer According to Normal Tissue Dose Constraints: An In Silico Clinical Trial

Journal Article · Tue Jul 15 04:00:00 EDT 2008 · International Journal of Radiation Oncology, Biology and Physics

DOI:https://doi.org/10.1016/j.ijrobp.2007.11.028· OSTI ID:21124356

Bosmans, Geert ^[1]; Bentzen, Soren M ^[2]; Boersma, Liesbeth; Dekker, Andre; Wanders, Rinus; Wouters, Bradly G; Lambin, Philippe; Ruysscher, Dirk de ^[1]

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1. Department of Radiation Oncology (MAASTRO), GROW Research Institute University Hospital Maastricht, Maastricht (Netherlands)
2. Department of Human Oncology, University of Wisconsin, Madison, WI (United States)

Purpose: Local tumor recurrence remains a major problem in patients with inoperable non-small-cell lung cancer undergoing radiotherapy. We investigated the theoretical gain in the estimated tumor control probability (TCP) using an individualized maximal tolerable dose (MTD) prescription, for both conventional and accelerated fractionation schemes. Methods and Materials: For 64 non-small-cell lung cancer patients, five treatment plans were compared, dependent on the normal tissue dose constraints for the lung and spinal cord. The first two used a classic fractionation (2 Gy/d, 5 d/wk) to a total dose of 60 Gy (QD{sub classic}) or determined by the individualized MTD (QD{sub MTD}). The third scheme assumed a hypofractionated schedule of 2.75-Gy fractions (QD{sub hypofr}). The fourth and fifth assumed hyperfractionation and acceleration (1.8 Gy twice daily, either BID{sub classic} or BID{sub MTD}). The TCPs for the groups of patients were estimated. Results: The mean biologic equivalent dose in 2-Gy fractions for tumor, corrected for accelerated repopulation was significantly greater for the BID{sub MTD} scheme (62.1 Gy) than for any other scheme (QD{sub classic}, 47.5 Gy; QD{sub MTD}, 52.0 Gy; QD{sub hypofr}, 56.9 Gy; and BID{sub classic}, 56.9 Gy; p < 0.001). Although both dose-escalation (QD{sub MTD}) and hypofractionation (QD{sub hypofr}) resulted in an increase in the mean estimated TCP of 5.6% (p < 0.001) and 14.6% (p < 0.001), respectively, compared with QD{sub classic}, the combination of escalation and acceleration (BID{sub MTD}) improved the mean estimated TCP by 26.4% (p < 0.001). Conclusion: The results of this planning study showed a large gain in the estimated TCP using an MTD scheme with 1.8-Gy fractions BID compared with other fractionation schedules. Clinical studies implementing this concept are ongoing.

• OSTI ID: 21124356
• Journal Information: International Journal of Radiation Oncology, Biology and Physics, Journal Name: International Journal of Radiation Oncology, Biology and Physics Journal Issue: 4 Vol. 71; ISSN IOBPD3; ISSN 0360-3016
• Country of Publication: United States
• Language: English

Related Subjects

62 RADIOLOGY AND NUCLEAR MEDICINE
CARCINOMAS
CLINICAL TRIALS
DOSE EQUIVALENTS
FRACTIONATION
LUNGS
PATIENTS
RADIATION DOSES
RADIOTHERAPY
SPINAL CORD
TOXICITY