Optimal delineation of the clinical target volume for thymomas in the post-resection setting: A multi-center study

F. Marcuse; S. Peeters; K. Herman; F. Vaassen; W. Van Elmpt; A.P.W.M. Maat; J. Praag; C. Billiet; P. Van Schil; M. Lambrecht; D. Van Raemdonck; K. Cao; M. Grigoroiu; N. Girard; M. Hochstenbag; J. Maessen; D. De Ruysscher

doi:10.1016/j.radonc.2021.10.007

Optimal delineation of the clinical target volume for thymomas in the post-resection setting: A multi-center study

F. Marcuse^*, S. Peeters, K. Herman, F. Vaassen, W. Van Elmpt, A.P.W.M. Maat, J. Praag, C. Billiet, P. Van Schil, M. Lambrecht, D. Van Raemdonck, K. Cao, M. Grigoroiu, N. Girard, M. Hochstenbag, J. Maessen, D. De Ruysscher

^*Corresponding author for this work

Research output: Contribution to journal › Article › Academic › peer-review

Abstract

Background: The definition of the clinical target volume (CTV) for post-operative radiotherapy (PORT) for thymoma is largely unexplored. The aim of this study was to analyze the difference in CTV delineation between radiation oncologists (RTO) and surgeons.Methods: This retrospective multi-center study enrolled 31 patients who underwent PORT for a thymoma from five hospitals. Three CTVs were delineated per patient: one CTV by the RTO, one CTV by the surgeon (blinded to the results of the RTO) and a joint CTV after collaboration. Volumes (cm(3)), Hausdorff distances (HD) and Dice similarity coefficients (DSC) were analyzed.Results: RTO delineated significantly bigger CTVs than surgeons (mean: 93.9 +/- 63.1, versus 57.9 +/- 61.3 cm(3), p = 0.003). Agreement was poor between RO and surgeons, with a low mean DSC (0.34 +/- 0.21) and high mean HD of 4.5 (+/- 2.2) cm. Collaborative delineation resulted in significantly smaller volumes compared to RTO (mean 57.1 +/- 58.6 cm(3), p < 0.001). A mean volume of 18.9 (+/- 38.1) cm(3) was included in joint contours, but missed by RTO. Conversely, a mean volume of 55.7 (+/- 39.9) cm(3) was included in RTO's delineations, but not in the joint delineations.Conclusions: To the best of our knowledge, this is the first study investigating CTV definition in thymoma. We demonstrated a significant variability between RTO and surgeons. Joint delineation prompted revisions in smaller CTV as well as favoring the surgeons' judgement, suggesting that surgeons provided relevant insight into other risk areas than RTO. We recommend a multidisciplinary approach to PORT for thymomas in clinical practice. (C) 2021 The Author(s). Published by Elsevier B.V.

Original language	English
Pages (from-to)	8-13
Number of pages	6
Journal	Radiotherapy and Oncology
Volume	165
DOIs	https://doi.org/10.1016/j.radonc.2021.10.007
Publication status	Published - 1 Dec 2021

Keywords

Thymomas
Thymectomy
Postoperative radiotherapy
Clinical target volume
RADIATION-THERAPY
INTEROBSERVER VARIABILITY
IMPACT
CLASSIFICATION
RADIOTHERAPY
GUIDELINES
DIAGNOSIS
ACCURACY
CANCERS
TUMORS

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Marcuse, F., Peeters, S., Herman, K., Vaassen, F., Van Elmpt, W., Maat, A. P. W. M., Praag, J., Billiet, C., Van Schil, P., Lambrecht, M., Van Raemdonck, D., Cao, K., Grigoroiu, M., Girard, N., Hochstenbag, M., Maessen, J., & De Ruysscher, D. (2021). Optimal delineation of the clinical target volume for thymomas in the post-resection setting: A multi-center study. Radiotherapy and Oncology, 165, 8-13. https://doi.org/10.1016/j.radonc.2021.10.007

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title = "Optimal delineation of the clinical target volume for thymomas in the post-resection setting: A multi-center study",

abstract = "Background: The definition of the clinical target volume (CTV) for post-operative radiotherapy (PORT) for thymoma is largely unexplored. The aim of this study was to analyze the difference in CTV delineation between radiation oncologists (RTO) and surgeons.Methods: This retrospective multi-center study enrolled 31 patients who underwent PORT for a thymoma from five hospitals. Three CTVs were delineated per patient: one CTV by the RTO, one CTV by the surgeon (blinded to the results of the RTO) and a joint CTV after collaboration. Volumes (cm(3)), Hausdorff distances (HD) and Dice similarity coefficients (DSC) were analyzed.Results: RTO delineated significantly bigger CTVs than surgeons (mean: 93.9 +/- 63.1, versus 57.9 +/- 61.3 cm(3), p = 0.003). Agreement was poor between RO and surgeons, with a low mean DSC (0.34 +/- 0.21) and high mean HD of 4.5 (+/- 2.2) cm. Collaborative delineation resulted in significantly smaller volumes compared to RTO (mean 57.1 +/- 58.6 cm(3), p < 0.001). A mean volume of 18.9 (+/- 38.1) cm(3) was included in joint contours, but missed by RTO. Conversely, a mean volume of 55.7 (+/- 39.9) cm(3) was included in RTO's delineations, but not in the joint delineations.Conclusions: To the best of our knowledge, this is the first study investigating CTV definition in thymoma. We demonstrated a significant variability between RTO and surgeons. Joint delineation prompted revisions in smaller CTV as well as favoring the surgeons' judgement, suggesting that surgeons provided relevant insight into other risk areas than RTO. We recommend a multidisciplinary approach to PORT for thymomas in clinical practice. (C) 2021 The Author(s). Published by Elsevier B.V.",

keywords = "Thymomas, Thymectomy, Postoperative radiotherapy, Clinical target volume, RADIATION-THERAPY, INTEROBSERVER VARIABILITY, IMPACT, CLASSIFICATION, RADIOTHERAPY, GUIDELINES, DIAGNOSIS, ACCURACY, CANCERS, TUMORS",

author = "F. Marcuse and S. Peeters and K. Herman and F. Vaassen and {Van Elmpt}, W. and A.P.W.M. Maat and J. Praag and C. Billiet and {Van Schil}, P. and M. Lambrecht and {Van Raemdonck}, D. and K. Cao and M. Grigoroiu and N. Girard and M. Hochstenbag and J. Maessen and {De Ruysscher}, D.",

year = "2021",

month = dec,

day = "1",

doi = "10.1016/j.radonc.2021.10.007",

language = "English",

volume = "165",

pages = "8--13",

journal = "Radiotherapy and Oncology",

issn = "0167-8140",

publisher = "Elsevier Ireland Ltd",

}

Marcuse, F, Peeters, S, Herman, K, Vaassen, F, Van Elmpt, W, Maat, APWM, Praag, J, Billiet, C, Van Schil, P, Lambrecht, M, Van Raemdonck, D, Cao, K, Grigoroiu, M, Girard, N, Hochstenbag, M , Maessen, J & De Ruysscher, D 2021, 'Optimal delineation of the clinical target volume for thymomas in the post-resection setting: A multi-center study', Radiotherapy and Oncology, vol. 165, pp. 8-13. https://doi.org/10.1016/j.radonc.2021.10.007

TY - JOUR

T1 - Optimal delineation of the clinical target volume for thymomas in the post-resection setting: A multi-center study

AU - Marcuse, F.

AU - Peeters, S.

AU - Herman, K.

AU - Vaassen, F.

AU - Van Elmpt, W.

AU - Maat, A.P.W.M.

AU - Praag, J.

AU - Billiet, C.

AU - Van Schil, P.

AU - Lambrecht, M.

AU - Van Raemdonck, D.

AU - Cao, K.

AU - Grigoroiu, M.

AU - Girard, N.

AU - Hochstenbag, M.

AU - Maessen, J.

AU - De Ruysscher, D.

PY - 2021/12/1

Y1 - 2021/12/1

N2 - Background: The definition of the clinical target volume (CTV) for post-operative radiotherapy (PORT) for thymoma is largely unexplored. The aim of this study was to analyze the difference in CTV delineation between radiation oncologists (RTO) and surgeons.Methods: This retrospective multi-center study enrolled 31 patients who underwent PORT for a thymoma from five hospitals. Three CTVs were delineated per patient: one CTV by the RTO, one CTV by the surgeon (blinded to the results of the RTO) and a joint CTV after collaboration. Volumes (cm(3)), Hausdorff distances (HD) and Dice similarity coefficients (DSC) were analyzed.Results: RTO delineated significantly bigger CTVs than surgeons (mean: 93.9 +/- 63.1, versus 57.9 +/- 61.3 cm(3), p = 0.003). Agreement was poor between RO and surgeons, with a low mean DSC (0.34 +/- 0.21) and high mean HD of 4.5 (+/- 2.2) cm. Collaborative delineation resulted in significantly smaller volumes compared to RTO (mean 57.1 +/- 58.6 cm(3), p < 0.001). A mean volume of 18.9 (+/- 38.1) cm(3) was included in joint contours, but missed by RTO. Conversely, a mean volume of 55.7 (+/- 39.9) cm(3) was included in RTO's delineations, but not in the joint delineations.Conclusions: To the best of our knowledge, this is the first study investigating CTV definition in thymoma. We demonstrated a significant variability between RTO and surgeons. Joint delineation prompted revisions in smaller CTV as well as favoring the surgeons' judgement, suggesting that surgeons provided relevant insight into other risk areas than RTO. We recommend a multidisciplinary approach to PORT for thymomas in clinical practice. (C) 2021 The Author(s). Published by Elsevier B.V.

AB - Background: The definition of the clinical target volume (CTV) for post-operative radiotherapy (PORT) for thymoma is largely unexplored. The aim of this study was to analyze the difference in CTV delineation between radiation oncologists (RTO) and surgeons.Methods: This retrospective multi-center study enrolled 31 patients who underwent PORT for a thymoma from five hospitals. Three CTVs were delineated per patient: one CTV by the RTO, one CTV by the surgeon (blinded to the results of the RTO) and a joint CTV after collaboration. Volumes (cm(3)), Hausdorff distances (HD) and Dice similarity coefficients (DSC) were analyzed.Results: RTO delineated significantly bigger CTVs than surgeons (mean: 93.9 +/- 63.1, versus 57.9 +/- 61.3 cm(3), p = 0.003). Agreement was poor between RO and surgeons, with a low mean DSC (0.34 +/- 0.21) and high mean HD of 4.5 (+/- 2.2) cm. Collaborative delineation resulted in significantly smaller volumes compared to RTO (mean 57.1 +/- 58.6 cm(3), p < 0.001). A mean volume of 18.9 (+/- 38.1) cm(3) was included in joint contours, but missed by RTO. Conversely, a mean volume of 55.7 (+/- 39.9) cm(3) was included in RTO's delineations, but not in the joint delineations.Conclusions: To the best of our knowledge, this is the first study investigating CTV definition in thymoma. We demonstrated a significant variability between RTO and surgeons. Joint delineation prompted revisions in smaller CTV as well as favoring the surgeons' judgement, suggesting that surgeons provided relevant insight into other risk areas than RTO. We recommend a multidisciplinary approach to PORT for thymomas in clinical practice. (C) 2021 The Author(s). Published by Elsevier B.V.

KW - Thymomas

KW - Thymectomy

KW - Postoperative radiotherapy

KW - Clinical target volume

KW - RADIATION-THERAPY

KW - INTEROBSERVER VARIABILITY

KW - IMPACT

KW - CLASSIFICATION

KW - RADIOTHERAPY

KW - GUIDELINES

KW - DIAGNOSIS

KW - ACCURACY

KW - CANCERS

KW - TUMORS

U2 - 10.1016/j.radonc.2021.10.007

DO - 10.1016/j.radonc.2021.10.007

M3 - Article

C2 - 34673091

SN - 0167-8140

VL - 165

SP - 8

EP - 13

JO - Radiotherapy and Oncology

JF - Radiotherapy and Oncology

ER -