RESUMEN
Radiation pneumonitis is a well-documented side effect of radiation therapy for breast cancer. The purpose of this study was to compare combined photon-electron, photon-only, and electron-only plans in the radiation treatment of the supraclavicular lymph nodes. In total, 13 patients requiring chest wall and supraclavicular nodal irradiation were planned retrospectively using combined photon-electron, photon-only, and electron-only supraclavicular beams. A dose of 50Gy over 25 fractions was prescribed. Chest wall irradiation parameters were fixed for all plans. The goal of this planning effort was to cover 95% of the supraclavicular clinical target volume (CTV) with 95% of the prescribed dose and to minimize the volume receiving ≥ 105% of the dose. Comparative end points were supraclavicular CTV coverage (volume covered by the 95% isodose line), hotspot volume, maximum radiation dose, contralateral breast dose, mean total lung dose, total lung volume percentage receiving at least 20 Gy (V(20 Gy)), heart volume percentage receiving at least 25 Gy (V(25 Gy)). Electron and photon energies ranged from 8 to 18 MeV and 4 to 6 MV, respectively. The ratio of photon-to-electron fractions in combined beams ranged from 5:20 to 15:10. Supraclavicular nodal coverage was highest in photon-only (mean = 96.2 ± 3.5%) followed closely by combined photon-electron (mean = 94.2 ± 2.5%) and lowest in electron-only plans (mean = 81.7 ± 14.8%, p < 0.001). The volume of tissue receiving ≥ 105% of the prescription dose was higher in the electron-only (mean = 69.7 ± 56.1 cm(3)) as opposed to combined photon-electron (mean = 50.8 ± 40.9 cm(3)) and photon-only beams (mean = 32.2 ± 28.1 cm(3), p = 0.114). Heart V(25 Gy) was not statistically different among the plans (p = 0.999). Total lung V(20 Gy) was lowest in electron-only (mean = 10.9 ± 2.3%) followed by combined photon-electron (mean = 13.8 ± 2.3%) and highest in photon-only plans (mean = 16.2 ± 3%, p < 0.001). As expected, photon-only plans demonstrated the highest target coverage and total lung V(20 Gy). The superiority of electron-only beams, in terms of decreasing lung dose, is set back by the dosimetric hotspots associated with such plans. Combined photon-electron treatment is a feasible technique for supraclavicular nodal irradiation and results in adequate target coverage, acceptable dosimetric hotspot volume, and slightly reduced lung dose.
Asunto(s)
Neoplasias de la Mama/radioterapia , Ganglios Linfáticos/efectos de la radiación , Metástasis Linfática/radioterapia , Tratamientos Conservadores del Órgano/métodos , Planificación de la Radioterapia Asistida por Computador/métodos , Radioterapia de Alta Energía/métodos , Terapia Combinada , Electrones/uso terapéutico , Humanos , Órganos en Riesgo/efectos de la radiación , Fotones/uso terapéutico , Protección Radiológica/métodos , Dosificación Radioterapéutica , Estudios Retrospectivos , Resultado del TratamientoRESUMEN
BACKGROUND AND OBJECTIVES: In recent years, there has been an increasing role for stem cell transplantation in the management of retinoblastoma. The aim of this study was to systematically review the role high-dose chemotherapy followed by stem cell transplantation in the treatment of patients with metastatic or relapsed, trilateral or bilateral advanced retinoblastoma, and in patients with tumor at the surgical margin of the optic nerve and/or extrascleral extension. DESIGN: Systematic literature review. METHODS: We performed an extensive PubMed database search on 25 February 2012 for studies describing the use of high-dose chemotherapy followed by stem cell transplantation in the management of patients with retinoblastoma. RESULTS: We located 15 studies that met the inclusion criteria and that included 101 patients. Following treatment for metastatic and relapsed disease, 44 of 77 patients (57.1%) were alive with no evidence of disease at the time of follow-up. However, a higher rate of local relapse developed in patients with CNS metastases (73.1%), which dropped to 47.1% in patients who received thiotepa. In patients with trilateral or bilateral advanced retinoblastoma, 5 of 7 (71.4%) with reported outcome data were alive with no evidence of disease at the time of follow-up. In patients with tumor at the surgical margin of the optic nerve and/or extrascleral extension, 6 of 7 patients (85.7%) were alive with no evidence of disease at the time of follow-up. CONCLUSIONS: Durable tumor control is possible in patients with non-CNS metastases, trilateral or bilateral advanced retinoblastoma, and in patients with tumor at the surgical margin of the optic nerve and/or extrascleral extension. Patients with CNS metastases require thiotepa to improve tumor control.