Pd-0439 CTV Margin in Laryngeal and Hypopharyngeal Cancer: A Histology Study

Caldas-Magalhaes, J.; Kooij, N.; Kasperts, N.; Pameijer, Frank A.; Terhaard, C.H.J.; Raaijmakers, Cornelis P.J.; Philippens, M.E.P.

doi:10.1016/s0167-8140(12)70778-8

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“… Recent studies indicate an over estimation of the GTV delineated on the planning CT scan of more than 3.5 mm [ 16 , 17 ]. Preliminary results of a study in which GTV delineations are validated with pathology showed that there is in 10 out of 15 patients no microscopical spread beyond 5 mm of the GTV delineated on a CT scan [ 18 ]. The incidence and total duration of swallowing is low.…”

Section: Methodsmentioning

confidence: 99%

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Consequences of tumor planning target volume reduction in treatment of T2-T4 laryngeal cancer

et al. 2014

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Background and purposeSince lymph nodes volumes are generally four times the volume of the primary PTV, the advantage of using tight margins around the primary PTV is not clear. Therefore treatment margins of T2-T4 laryngeal carcinoma for IMRT are generally chosen in such a way that the PTV is comparable to that in conventional radiotherapy. The aim of this study is to quantify the effect of volume reduction of the primary PTV of T2-T4 laryngeal carcinoma with regard to late toxicity despite elective irradiation of lymph node levels II to IV.MethodsTwo treatment plans based on conservative (GTV-PTV = 15 mm and 20 mm cranial), and on evidence-based tight margins (GTV-PTV = 8 mm) were calculated for 16 patients. Toxicity effects were estimated based on the dose distributions.ResultsCompared to conservative margins, using tight margins resulted in: 1) significant reduction of the normal tissue complication probability (NTCP) for swallowing muscles and submandibular glands, 2) significant reduction of the mean dose in all organs at risk (OAR), 3) a mean dose smaller than 60 Gy for all OARs except for the laryngeal cartilages. When the lymph node levels II to IV were prescribed with an elective dose, an NTCP reduction of 53% for the swallowing muscles and of 23% for the submandibular glands was found by using tight instead of conservative margins. When positive nodes were present, NTCP reduction amounted to 29% and 15%, respectively.ConclusionsThere is a potential benefit in realizing evidence-based tight margins for laryngeal cancer patients despite elective irradiation of lymph node levels II to IV.

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Section: Methodsmentioning

confidence: 99%

“…Preliminary results of a study in which GTV delineations are validated with pathology showed that there is in 10 out of 15 patients no microscopical spread beyond 5 mm of the GTV delineated on a CT scan [ 18 ].…”

Section: Methodsmentioning

confidence: 99%