RESUMO
PURPOSE: The local control of inoperable non-small cell lung cancer (NSCLC) using standard radiotherapy (RT) doses is inadequate. Dose escalation is a potential strategy to improve the local control for patients with NSCLC; however, the optimal dose required for local control in this setting is unknown. METHODS AND MATERIALS: Patients with unresectable or inoperable stage II/III NSCLC with ECOG≤1 received 48 Gy in 20 daily fractions using intensity-modulated radiotherapy, followed by 1 of 3 boost dose levels: 16.8 Gy/7 (cumulative 2 Gy equivalent dose [EQD2]â 76 Gy/38), 20.0 Gy/7 (EQD2â 84 Gy/42), and 22.7 Gy/7 (EQD2â 92 Gy/46). Two cycles of cisplatin/etoposide chemotherapy were given concurrent with RT. The maximum tolerated dose was defined as the dose at which ≥30% experienced dose-limiting toxicity (any NCIC Common Terminology for Adverse Events V3.0 grade 3 or higher acute toxicity). RESULTS: Twelve patients completed treatment with a median follow-up of 22 months (range, 7 to 48). The median age was 72 (range, 54 to 80) and 50% of patients had adenocarcinoma. Five, 3, and 4 patients were treated on dose levels 1, 2, and 3, respectively. No dose-limiting toxicity was observed. One-year local progression-free survival and overall survival estimates were 81% and 58%, respectively. CONCLUSIONS: Hypofractionated intensity-modulated radiotherapy was well tolerated and provided meaningful local control for patients with locally advanced inoperable NSCLC. The maximum tolerated dose of RT in this setting lies beyond an EQD2 of 92 Gy/46 and further dose escalation in this setting is warranted.
Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Carcinoma Pulmonar de Células não Pequenas/terapia , Neoplasias Pulmonares/terapia , Radioterapia de Intensidade Modulada/métodos , Idoso , Idoso de 80 Anos ou mais , Carcinoma Pulmonar de Células não Pequenas/diagnóstico por imagem , Quimiorradioterapia/efeitos adversos , Cisplatino/administração & dosagem , Intervalo Livre de Doença , Etoposídeo/administração & dosagem , Feminino , Humanos , Neoplasias Pulmonares/diagnóstico por imagem , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Hipofracionamento da Dose de Radiação , Radioterapia de Intensidade Modulada/efeitos adversos , Critérios de Avaliação de Resposta em Tumores Sólidos , Taxa de Sobrevida , Tomografia Computadorizada por Raios XRESUMO
This study investigated the dosimetric advantages of inversely planned intensity-modulated radiotherapy (IMRT) over forward-planned conventional 3D conformal radiotherapy (3D-CRT) in treating lung cancer patients at escalated dose. Three consecutively accrued patients on the RTOG 93-11 dose-escalation protocol were replanned using IMRT with the same dosimetric rules, so that the isodose distributions and dose-volume histograms could be generated and compared. The Helax-TMS treatment planning system, with an IMRT optimization module (version 6.0), was used. In all cases, a consistent approach of inverse planning and set of dose-volume constraints (DVCs) provided improved critical structure sparing. However, the minimum dose in PTV was generally below that achieved with the corresponding forward planned 3D-CRT.
Assuntos
Algoritmos , Neoplasias Pulmonares/radioterapia , Planejamento da Radioterapia Assistida por Computador , Radioterapia Conformacional , Humanos , Dosagem RadioterapêuticaRESUMO
The intensity modulated arc has been proposed as an alternative to tomotherapy. Treatment planing systems more typically model the conventional step and shoot or sliding window dynamic multileaf collimator (DMLC) deliveries, and may not support intensity modulated arc therapy (IMAT). As well, another potential drawback to this technique is that increasing the number of intensity levels required to achieve certain dose distributions necessitates increasing the number of gantry passes, as may occur if the desired dose distribution is complex (e.g., concave or bifurcated), potentially increasing the overall treatment time. A technique is presented here for the delivery of tomotherapy like dose distributions in a single gantry pass by the use of a large number of fields modulated by a sliding window DMLC technique from fixed equally spaced gantry positions. This serves as a good approximation to either IMAT or tomotherapy deliveries. The planning of these fields is achieved using iterative filtered back projection. Measured results of deliveries of varying degrees of complexity on a homogeneous phantom are compared to desired distributions.