RESUMEN
OBJECTIVES: Target volumes for irradiation remain ill-defined for squamous cell cancer of unknown primary in the head and neck (SCCUP). The aim of this study was to compare involved neck only (INO) radiotherapy (RT) with irradiating involved neck plus potential mucosal primary sites and contralateral neck (MUC) in patients diagnosed and treated with modern diagnostics and techniques. DESIGN: This is a retrospective cohort study. Patients with a diagnosis of SCCUP with unilateral neck disease were included. RESULTS: Thirty patients were identified. All underwent FDG PET-CT. 47% of patients had HPV-positive SCC. 20 patients received RT to INO, 10 patients to MUC, all with volumetric modulated arc therapy (VMAT). A significantly lower dose for each organ at risk was delivered in INO-treated patients, with mean dose to contralateral parotid gland 57% less. The proportion of patients with late grade 2 or worse xerostomia was higher in MUC patients. The incidence of grade 2-3 mucositis (89% vs 45%) and grade 3 or worse dysphagia (50% vs 10%) was higher in MUC patients. Median follow-up was 31 months. No mucosal primaries emerged. Progression-free survival at 2 years was 74.7% for INO patients, 70% in the MUC group. Overall survival at 2 years was 79.7% in the INO group and 70% in the MUC patients. CONCLUSION: INO radiotherapy for patients with SCCUP of the head and neck is a safe treatment strategy resulting in clinically significant lower RT doses to OARS. Acute and late toxicities are reduced without detriment to patient survival.
Asunto(s)
Carcinoma de Células Escamosas/radioterapia , Neoplasias de Cabeza y Cuello/radioterapia , Neoplasias Primarias Desconocidas/radioterapia , Radioterapia de Intensidad Modulada , Anciano , Carcinoma de Células Escamosas/diagnóstico por imagen , Carcinoma de Células Escamosas/mortalidad , Femenino , Fluorodesoxiglucosa F18 , Neoplasias de Cabeza y Cuello/diagnóstico por imagen , Neoplasias de Cabeza y Cuello/mortalidad , Humanos , Masculino , Persona de Mediana Edad , Mucositis/etiología , Neoplasias Primarias Desconocidas/diagnóstico por imagen , Neoplasias Primarias Desconocidas/mortalidad , Órganos en Riesgo , Tomografía Computarizada por Tomografía de Emisión de Positrones , Radiofármacos , Estudios Retrospectivos , Tasa de Supervivencia , Xerostomía/etiologíaRESUMEN
BACKGROUND: The purpose of this study was to demonstrate how magnetic resonance imaging (MRI) patient position protocols influence registration quality in patients with oropharyngeal cancer undergoing radical radiotherapy and the consequences for gross tumour volume (GTV) definition and radiotherapy planning. METHODS AND MATERIALS: Twenty-two oropharyngeal patients underwent a computed tomography (CT), a diagnostic MRI (MRI(D)) and an MRI in the radiotherapy position within an immobilization mask (MRI(RT)). Clinicians delineated the GTV on the CT viewing the MRI(D) separately (GTV(C)); on the CT registered to MRI(D) (GTV(D)) and on the CT registered to MRI(RT) (GTV(RT)). Planning target volumes (PTVs) were denoted similarly. Registration quality was assessed by measuring disparity between structures in the three set-ups. Volumetric modulated arc therapy (VMAT) radiotherapy planning was performed for PTV(C), PTV(D) and PTV(RT). To determine the dose received by the reference PTV(RT), we optimized for PTV(C) and PTV(D) while calculating the dose to PTV(RT). Statistical significance was determined using the two-tailed Mann-Whitney or two-tailed paired student t-tests. RESULTS: A significant improvement in registration accuracy was found between CT and MRI(RT) versus the MRI(D) measuring distances from the centre of structures (geometric mean error of 2.2 mm versus 6.6 mm). The mean GTV(C) (44.1 cm3) was significantly larger than GTV(D) (33.7 cm3, p value = 0.027) or GTV(RT) (30.5 cm3, p value = 0.014). When optimizing the VMAT plans for PTV(C) and investigating the mean dose to PTV(RT) neither the dose to 99% (58.8%) nor 95% of the PTV (84.7%) were found to meet the required clinical dose constraints of 90% and 95% respectively. Similarly, when optimizing for PTV(D) the mean dose to PTV(RT) did not meet clinical dose constraints for 99% (14.9%) nor 95% of the PTV (66.2%). Only by optimizing for PTV(RT) were all clinical dose constraints achieved. CONCLUSIONS: When oropharyngeal patients MRI scans are performed in the radiotherapy position there are significant improvements in CT-MR image registration, target definition and PTV dose coverage.