Table 1.
Patient and tumor characteristics.
Fig 1.
A representative case treated with carbon-ion radiotherapy.
(A) A 91-year-old man with T3N0M0 lung squamous cell carcinoma. A rapidly growing tumor was 73 mm in diameter. (18) F-Fluorodeoxyglucose positron emission tomography (FDG-PET) images revealed that the tumoral maximum standardized uptake value was 12.1 and tumor to normal tissue (T/N) ratio was 3.8. The patient was considered inoperable because of his age and chronic obstructive pulmonary disease. (B) Carbon-ion radiotherapy was performed using a respiratory-gated technique with 60 Gy (relative biological effectiveness) in 4 fractions. The GTV, CTV, and PTV are represented by the red, cyan, and magenta lines, respectively. (C) Following treatment, asymptomatic grade 1 radiation pneumonitis developed but additional treatment was not required. Two years after carbon-ion radiotherapy, FDG-PET images demonstrated reductions in the maximum standardized uptake value from 12.1 to 2.5 and in the T/N ratio from 3.8 to 1.0. Distant or lymph node metastases were not detected. The patient was still alive without disease progression at 3 years after carbon-ion radiotherapy.
Fig 2.
Local control curves of T2b–4N0M0 non-small cell lung cancer patients treated with carbon-ion radiotherapy.
(A) The 2-year local control rate for all patients (n = 23) was 81%. (B) The 2-year local control rates of patients with a gross tumor volume (GTV) of <59 cm3 (n = 11) or ≥59 cm3 (n = 12) were 100% and 39%, respectively (P = 0.02).
Fig 3.
Overall survival curves of T2b–4N0M0 non-small cell lung cancer patients treated with carbon-ion radiotherapy.
(A) The 2-year overall survival rate for all patients (n = 23) was 70%. (B) The 2-year overall survival rates of patients in the operable (n = 11) and inoperable (n = 12) groups were 100% and 43%, respectively (P = 0.04).
Table 2.
Adverse events in patients (n = 23) treated with carbon-ion radiotherapy.
Fig 4.
A comparison of dose distribution between carbon-ion radiotherapy and photon therapies in a representative case.
(A) Left: The dose distribution of three-dimensional radiotherapy (3DCRT). Right: The dose distribution of intensity-modulated radiotherapy (IMRT). The irradiated volume of the carbon-ion radiotherapy (See Fig 1B) was smaller compared with those of the photon therapies. (B) Dose-volume histograms of the planning target volume (PTV; red) and lung (yellow) for the carbon-ion radiotherapy (solid line), IMRT (dashed line), and 3DCRT (dotted line). RBE, relative biological effectiveness.
Fig 5.
Comparisons of lung dose-volume between carbon-ion radiotherapy and photon therapies.
Carbon-ion radiotherapy is represented by the blue line, three-dimensional radiotherapy (3DCRT) by the black line, and intensity-modulated radiotherapy (IMRT) by the red line. 3DCRT had significantly higher irradiated lung volumes of V5, V10, V20, and V30 compared with the carbon-ion radiotherapy (Black asterisk). IMRT had significantly higher irradiated lung volumes of V5, V10, and V20 compared with the carbon-ion radiotherapy (Red asterisk). Asterisks (*) represent P < 0.05. RBE, relative biological effectiveness; Vx, normal lung volume receiving X Gy.
Table 3.
Comparison of planning target volume (PTV) parameters between carbon-ion radiotherapy and photon therapies, including three-dimensional radiotherapy (3DCRT) or intensisty-modulated radiotherapy (IMRT).