Anatomical change during radiotherapy for head and neck cancer, and its effect on delivered dose to the spinal cord.
Seah, Shannon YK
Bates, Amy M
Barnett, Gillian C
Benson, Richard J
Jefferies, Sarah J
Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology
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Noble, D., Yeap, P., Seah, S. Y., Harrison, K., Shelley, L., Romanchikova, M., Bates, A. M., et al. (2019). Anatomical change during radiotherapy for head and neck cancer, and its effect on delivered dose to the spinal cord.. Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology, 130 32-38. https://doi.org/10.1016/j.radonc.2018.07.009
Background and purpose: The impact of weight loss and anatomical change during head and neck (H&N) radiotherapy on spinal cord dosimetry is poorly understood, limiting evidence-based adaptive management strategies. Materials and methods: 133 H&N patients treated with daily mega-voltage CT image-guidance (MVCT-IG) on TomoTherapy, were selected. Elastix software was used to deform planning scan SC contours to MVCT-IG scans, and accumulate dose. Planned (DP) and delivered (DA) spinal cord D2% (SCD2%) were compared. Univariate relationships between neck irradiation strategy (unilateral vs bilateral), T-stage, N-stage, weight loss, and changes in lateral separation (LND) and CT slice surface area (SSA) at C1 and the superior thyroid notch (TN), and ΔSCD2% [(DA – DP) D2%] were examined. Results: The mean value for (DA – DP) D2% was -0.07Gy (95%CI -0.28 to 0.14, range -5.7Gy to 3.8Gy), and the mean absolute difference between DP and DA (independent of difference direction) was 0.9Gy (95%CI 0.76 to 1.04Gy). Neck treatment strategy (p=0.39) and T-stage (p=0.56) did not affect ΔSCD2%. Borderline significance (p=0.09) was seen for higher N-stage (N2-3) and higher ΔSCD2%. Mean reductions in anatomical metrics were substantial: weight loss 6.8kg; C1LND 12.9mm; C1SSA 12.1cm2; TNLND 5.3mm; TNSSA 11.2cm2, but no relationship between weight loss or anatomical change and ΔSCD2% was observed (all r2<0.1). Conclusions: Differences between delivered and planned spinal cord D2% are small in patients treated with daily IG. Even patients experiencing substantial weight loss or anatomical change during treatment do not require adaptive replanning for spinal cord safety.
Spinal Cord, Humans, Head and Neck Neoplasms, Tomography, X-Ray Computed, Radiotherapy Dosage, Radiotherapy Planning, Computer-Assisted, Middle Aged, Female, Male, Radiotherapy, Intensity-Modulated, Radiotherapy, Image-Guided
- The VoxTox project received a 5-year programme grant from Cancer Research UK (CRUK) (Ref: C8857/A13405). - KH, MR and AMB were supported by the programme grant. - DJN is supported by a CRUK Clinical Research Fellowship (Ref: C20/A20917). - PLY and SYKS were supported by the Singapore Government. - LEAS is supported by the University of Cambridge W D Armstrong Trust Fund. - NGB was supported by the NIHR Cambridge Biomedical Research Centre.
Addenbrooke's Charitable Trust (ACT) (24/15 A/Noble)
Cancer Research UK (C20/A20917)
External DOI: https://doi.org/10.1016/j.radonc.2018.07.009
This record's URL: https://www.repository.cam.ac.uk/handle/1810/284584
Attribution 4.0 International
Licence URL: https://creativecommons.org/licenses/by/4.0/