Assessment and topographic characterization of locoregional recurrences in head and neck tumours

• Autor(a) principal: Ferreira, Brigida Costa
• Data de Publicação: 2015
• Outros Autores: Marques, Rui Vale, Khouri, Leila, Santos, Tânia, Sá-Couto, Pedro, do Carmo Lopes, Maria
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10316/109300; https://doi.org/10.1186/s13014-015-0345-4
• topic: Head and neck tumours; Radiation therapy; Characterization of tumour recurrences; Geometric methods; Dosimetric assessment; Adolescent; Adult; Aged; Aged, 80 and over; Carcinoma, Squamous Cell; Child; Female; Follow-Up Studies; Head and Neck Neoplasms; Humans; Male; Middle Aged; Neoplasm Recurrence, Local; Neoplasm Staging; Prognosis; Radiotherapy; Radiotherapy Planning, Computer-Assisted; Radiotherapy, Intensity-Modulated; Retrospective Studies; Risk Assessment; Survival Rate; Tomography, X-Ray Computed; Young Adult

Purpose: To evaluate the differences between three methods of classification of recurrences in patients with head and neck tumours treated with Radiation Therapy (RT). Materials and methods: 367 patients with head and neck tumours were included in the study. Tumour recurrences were delineated in the CT images taken during patient follow-up and deformable registration was used to transfer this volume into the planning CT. The methods used to classify recurrences were: method CTV quantified the intersection volume between the recurrence and the Clinical Target Volume (CTV); method TV quantified the intersection between the Treated Volume and the recurrence (for method CTV and TV, recurrences were classified in-field if more than 95% of their volume were inside the volume of interest, marginal if the intersection was between 20-95% and outfield otherwise); and method COM was based on the position of the Centre Of Mass of the recurrence. A dose assessment in the recurrence volume was also made. Results: The 2-year Kaplan-Meier locoregional recurrence incidence was 10%. Tumour recurrences occurred in 22 patients in a mean time of 16.5 ± 9.4 months resulting in 28 recurrence volumes. The percentage of in-field recurrences for methods CTV, TV and COM was 7%, 43% and 50%, respectively. Agreement between the three methods in characterizing individually in-field and marginal recurrences was found only in six cases. Methods CTV and COM agreed in 14. The percentage of outfield recurrences was 29% using all methods. For local recurrences (in-field or marginal to gross disease) the average difference between the prescribed dose and D98% in the recurrence volume was -5.2 ± 3.5% (range: -10.1%-0.9%). Conclusions: The classification of in-field and marginal recurrences is very dependent on the method used to characterize recurrences. Using methods TV and COM the largest percentage of tumour recurrences occurred in-field in tissues irradiated with high doses.