Patterns of Locoregional Failure After Exclusive IMRT for Oropharyngeal Carcinoma
- Department of Radiation Oncology, University of Texas Medical Branch, Galveston, TX (United States)
- Department of Medical Physics, University of Texas Medical Branch, Galveston, TX (United States)
- Department of Neuroradiology, University of Texas Medical Branch, Galveston, TX (United States)
Purpose: To assess the patterns of failure after intensity-modulated radiotherapy (IMRT) for oropharyngeal squamous cell carcinoma (SCC). Methods and Materials: We analyzed patients treated at the University of Texas Medical Branch between May 2002 and February 2006 who met the following criteria: (1) definitive IMRT without chemotherapy for oropharyngeal SCC; (2) no pretreatment radical surgery; (3) minimal follow-up of 1 year. The location of each nodal/primary failure was co-registered to the pretreatment planning computed tomography scan and then expanded by 5 mm to a planning target volume (PTV) of the failure (PTV-f). We then investigated whether the prescription dose to the PTV-f had been appropriate for the amount of disease present before treatment and whether the PTV-f had been adequately covered. Results: A total of 50 patients were eligible. With a median follow-up of 32.6 months (range, 12.1-58.6), three local and six regional failures were observed in 8 patients. All but one failure, that had been neglected, were recorded within 14 months of the treatment end. Of the nine failures, four developed in the neck treated electively to the lowest dose level; in all of them, we could retrospectively identify initial positive lymph nodes that might have justified the subsequent failure. The remaining five failures developed in proximity of the high-dose volume. In all but one, the volume of region of interest receiving {>=}95% of the dose of the PTV-f was >95%, suggesting adequate coverage. In 1 patient, about 20% of PTV-f was outside the 95% isodose, so that marginal underdosing could not be ruled out. Conclusions: A potential cause could be identified in all the failures in the lowest dose level. The implications and possible remedies are discussed. Most failures around the high-dose region were 'true failures' with no apparent technical caus000.
- OSTI ID:
- 21128204
- Journal Information:
- International Journal of Radiation Oncology, Biology and Physics, Vol. 72, Issue 3; Other Information: DOI: 10.1016/j.ijrobp.2008.01.027; PII: S0360-3016(08)00145-4; Copyright (c) 2008 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); ISSN 0360-3016
- Country of Publication:
- United States
- Language:
- English
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