PROOF OF PRINCIPLE OF OCULAR SPARING IN DOGS WITH SINONASAL TUMORS TREATED WITH INTENSITY‐MODULATED RADIATION THERAPY |
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| Authors: | JESSICA A LAWRENCE LISA J FORREST MICHELLE M TUREK PAUL E MILLER T ROCKWELL MACKIE HAZIM A JARADAT DAVID M VAIL RICHARD R DUBIELZIG RICHARD CHAPPELL MINESH P MEHTA |
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| Institution: | 1. School of Veterinary Medicine, Department of Medical Sciences, 2015 Linden Drive, Madison, WI 53706;2. Department of Surgical Sciences, 2015 Linden Drive, Madison, WI 53706;3. The Paul P. Carbone Comprehensive Cancer Center, Department of Medical Physics, University of Wisconsin‐Madison, 750 Highland Avenue, Madison, WI 53705;4. Department of Human Oncology, University of Wisconsin‐Madison, 750 Highland Avenue, Madison, WI 53705;5. Department of Biostatistics and Medical Informatics, University of Wisconsin‐Madison, 750 Highland Avenue, Madison, WI 53705;6. TomoTherapy Inc., 1430 Deming Way, Madison, WI 53717;7. Department of Pathobiological Sciences, 2015 Linden Drive, Madison, WI 53706;8. School of Medicine and Public Health, University of Wisconsin‐Madison, 750 Highland Avenue, Madison, WI 53705 |
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| Abstract: | Intensity‐modulated radiation therapy (IMRT) allows optimization of radiation dose delivery to complex tumor volumes with rapid dose drop‐off to surrounding normal tissues. A prospective study was performed to evaluate the concept of conformal avoidance using IMRT in canine sinonasal cancer. The potential of IMRT to improve clinical outcome with respect to acute and late ocular toxicity was evaluated. Thirty‐one dogs with sinonasal cancer were treated definitively with IMRT using helical tomotherapy and/or dynamic multileaf collimator (DMLC) delivery. Ocular toxicity was evaluated prospectively and compared with a comparable group of historical controls treated with conventional two‐dimensional radiotherapy (2D‐RT) techniques. Treatment plans were devised for each dog using helical tomotherapy and DMLC that achieved the target dose to the planning treatment volume and limited critical normal tissues to the prescribed dose–volume constraints. Overall acute and late toxicities were limited and minor, detectable by an experienced observer. This was in contrast to the profound ocular morbidity observed in the historical control group treated with 2D‐RT. Overall median survival for IMRT‐treated and 2D‐treated dogs was 420 and 411 days, respectively. Compared with conventional techniques, IMRT reduced dose delivered to eyes and resulted in bilateral ocular sparing in the dogs reported herein. These data provide proof‐of‐principle that conformal avoidance radiotherapy can be delivered through high conformity IMRT, resulting in decreased normal tissue toxicity as compared with historical controls treated with 2D‐RT. |
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| Keywords: | canine ocular sparing oncology radiation therapy tomotherapy toxicity |
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