Planning study for Merkel cell carcinoma based on the relapse pattern

Publication date: Available online 8 March 2017
Source:Radiotherapy and Oncology
Author(s): Ulrike Hoeller, Tina Schubert, Thomas Mueller, Volker Budach, Pirus Ghadjar, Winfried Brenner, Wolf Kuschke
PurposeTo develop a technique for radiation (RT) of in-transit path ways (IT) in Merkel cell carcinoma.MethodIn the planning study, IT were ink-marked on the skin during sentinel lymphscintigraphy and wire-marked in planning-CT. Pre- and post-operative planning-CTs were acquired. The clinical target volume (CTV) included tumor bed plus safety margin, IT and draining nodes, the planning volume (PTV) the CTV plus 0.5–1cm margin. VMAT plans with 2–3 arcs were analyzed.ResultsA planning study was performed for five pts. including two pts. with primary tumor (PT) in head and neck, 1 pt. each with PT of elbow, forearm and upper leg respectively. Plans showed satisfactory PTV coverage: Dmean 100%±0%, D98% 92.4%±2.24%, homogeneity index (HI) 0.095±0.01, conformation number (CN) 0.84±0.01 and conformality index (CI) 0.95±0.01.ConclusionThe planning study confirms feasibility of highly conformal irradiation of IT pathways based on individualized target delineation. Currently, patients referred for non-metastatic MCC are encouraged to enroll in a prospective clinical study that evaluates the feasibility of radiation of IT pathways.



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