TY - JOUR
T1 - Multidisciplinary approach to target volume delineation in locally recurrent rectal cancer
T2 - An explorative study
AU - Piqeur, F.
AU - van Gruijthuijsen, D. S.C.
AU - Nederend, J.
AU - Ceha, H.
AU - Stam, T.
AU - Dieters, M.
AU - Meijnen, P.
AU - Bakker-van der Jagt, M.
AU - Intven, M.
AU - Verrijssen, A. E.
AU - Cnossen, J. S.
AU - Berbee, M.
AU - Hartogh, M. den
AU - Bantema-Joppe, E. J.
AU - De Kroon, M.
AU - Paardekooper, G.
AU - Gielens, M. P.M.
AU - Daniels-Gooszen, A. W.
AU - Lahaye, M. J.
AU - Lambregts, D. M.J.
AU - Oei, S. A.
AU - Houwers, J. B.
AU - Horsthuis, K.
AU - Hurkmans, C.
AU - Rutten, H.
AU - Burger, J. W.A.
AU - Marijnen, C. A.M.
AU - Peulen, H.
N1 - Publisher Copyright:
© 2025 The Author(s)
PY - 2025/7/1
Y1 - 2025/7/1
N2 - Background and purpose: Interobserver variation (IOV) in locally recurrent rectal cancer (LRRC) delineations is large, possibly because of different interpretations of imaging. An explorative study was performed to investigate the benefit of additional delineations by expert radiologists. Materials and methods: 14 cases of LRRC were delineated on planning CT by 8 radiologists (RADs) to construct a median and total radiology contour, followed by 12 radiation oncologists (ROs), without (GTV-) or with (GTV+) the additional contours. IOV was calculated separately for RADs, GTV- and GTV+. The following metrics were used: the Surface Dice Similarity Coefficient (SDSC), Dice similarity coefficient (DSC), and Hausdorff Distance at the 98th percentile (HD98%). The median SDSC, DSC, and HD98% of GTV- and GTV+ were compared. Sub-analyses of IOV in different recurrence types were performed. Results: Median SDSC significantly improved from GTV- to GTV+ overall, but a significant benefit could not be proven in individual cases. Additional radiological input consistently improved all parameters in 4/14 cases (29 %). Geographical miss occurred after radiological input in 7 %. Subgroup analyses show large IOV in mainly fibrotic and intraluminal recurrences. Little IOV is seen in solitary nodal recurrences. Conclusion: This study highlights target volume delineation challenges in LRRC. Overall, radiological input reduced IOV amongst ROs in target volume delineation for LRRC. Large differences do however exist amongst recurrence types. A standard terminology for LRRC and close collaboration between radiologists and radiation oncologists seems necessary to reduce IOV and improve quality of care.
AB - Background and purpose: Interobserver variation (IOV) in locally recurrent rectal cancer (LRRC) delineations is large, possibly because of different interpretations of imaging. An explorative study was performed to investigate the benefit of additional delineations by expert radiologists. Materials and methods: 14 cases of LRRC were delineated on planning CT by 8 radiologists (RADs) to construct a median and total radiology contour, followed by 12 radiation oncologists (ROs), without (GTV-) or with (GTV+) the additional contours. IOV was calculated separately for RADs, GTV- and GTV+. The following metrics were used: the Surface Dice Similarity Coefficient (SDSC), Dice similarity coefficient (DSC), and Hausdorff Distance at the 98th percentile (HD98%). The median SDSC, DSC, and HD98% of GTV- and GTV+ were compared. Sub-analyses of IOV in different recurrence types were performed. Results: Median SDSC significantly improved from GTV- to GTV+ overall, but a significant benefit could not be proven in individual cases. Additional radiological input consistently improved all parameters in 4/14 cases (29 %). Geographical miss occurred after radiological input in 7 %. Subgroup analyses show large IOV in mainly fibrotic and intraluminal recurrences. Little IOV is seen in solitary nodal recurrences. Conclusion: This study highlights target volume delineation challenges in LRRC. Overall, radiological input reduced IOV amongst ROs in target volume delineation for LRRC. Large differences do however exist amongst recurrence types. A standard terminology for LRRC and close collaboration between radiologists and radiation oncologists seems necessary to reduce IOV and improve quality of care.
KW - Interobserver variation
KW - Locally recurrent rectal cancer
KW - Multidisciplinary collaboration
KW - Target volume delineation
U2 - 10.1016/j.ctro.2025.100948
DO - 10.1016/j.ctro.2025.100948
M3 - Article
SN - 2405-6308
VL - 53
JO - Clinical and Translational Radiation Oncology
JF - Clinical and Translational Radiation Oncology
M1 - 100948
ER -