Article
Clinical outcomes of proton beam therapy for early stage non-small cell lung cancer – a retrospective analysis of Shizuoka experiences
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Published: | September 24, 2009 |
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Background: Proton beam therapy (PBT) with several beam ports using a respiratory gating irradiation system can achieve a good dose distribution without an excessive dose to normal lung tissue and other thoracic organs for early lung cancer. So it may become an alternative treatment modality for the patients with medically inoperable problems. We retrospectively evaluated the safety and efficacy of definitive PBT for Stage I non-small cell lung cancer (NSCLC) at Shizuoka Cancer Center Hospital about 5 years from the start of PBT.
Material and methods: Between November 2003 and April 2007, 24 patients with pathologically proven clinical Stage I NSCLC were treated in our institution. Patient characteristics and their number were as follows: median age (range) (y), 75 (56–87); men/women (n), 21/3; Stage IA/IB/post-operative recurrence, 6/16/2; histology (adenocarcinoma/squamous cell carcinoma/others) (n) 14/9/1; medically inoperable/refusal of surgery, 16/8. The median duration of follow-up in all patients was 30 months (range, 3–52 months). Thoracic computed tomography images obtained in the exhalation phase with a respiratory gating system were used for PBT planning. The planning target volume was defined as the clinical target volume with a setup margin and an internal margin for uncertainty of respiratory motion. Daily verification of patient position by the image subtraction method with digitally reconstructed radiography and respiratory gating irradiation system delivering proton beams to the target volume in the exhalation phase were used. A total dose of 80 GyE (GyE: proton Gy*RBE (1.1)) was delivered in 20 fractions in all patients.
Results: One local tumor regrowth was observed in Stage IB case. Six patients experienced lymph node or distal recurrence. The 2-year overall survival rates, progression-free survival rates, local control rates were 96%, 79%, 94%, respectively. No serious acute toxicity was observed. The shortness of breath on effort, fracture of costal bone and chest pain were observed as late toxicities in several cases.
Conclusions: PBT is a promising treatment modality for early stage NSCLC, especially for medically inoperable patients.