Feasibility study of stereotactic body radiotherapy for peripheral lung tumors with a maximum dose of 100 Gy in five fractions and a heterogeneous dose distribution in the planning target volume.
We evaluated toxicity and outcomes for patients with peripheral lung tumors treated with stereotactic body radiation therapy (SBRT) in a dose-escalation and dose-convergence study. A total of 15 patients were enrolled. SBRT was performed with 60 Gy in 5 fractions (fr.) prescribed to the 60% isodose line of maximum dose, which was 100 Gy in 5 fr., covering the planning target volume (PTV) surface (60 Gy/5 fr. - (60%-isodose)) using dynamic conformal multiple arc therapy (DCMAT). The primary endpoint was radiation pneumonitis (RP) ≥ Grade 2 within 6 months. Toxicities were graded according to the Common Terminology Criteria for Adverse Events, version 4.0. Using dose-volumetric analysis, the trial regimen of 60 Gy/5 fr. - (60%-isodose) was compared with our institutional conventional regimen of 50 Gy/5 fr. - (80%-isodose). The enrolled consecutive patients had either a solitary peripheral tumor or two ipsilateral tumors. The median follow-up duration was 22.0 (12.0-27.0) months. After 6 months post-SBRT, the respective number of RP Grade 0, 1 and 2 cases was 5, 9 and 1. In the Grade 2 RP patient, the image showed an organizing pneumonia pattern at 6.0 months post-SBRT. No other toxicity was found. At last follow-up, there was no evidence of recurrence of the treated tumors. The target volumes of 60 Gy/ 5 fr. - (60%-isodose) were irradiated with a significantly higher dose than those of 50 Gy/5 fr. - (80%-isodose), while the former dosimetric parameters of normal lung were almost equivalent to the latter. SBRT with 60 Gy/5 fr. - (60%-isodose) using DCMAT allowed the delivery of very high and convergent doses to peripheral lung tumors with feasibility in the acute and subacute phases. Further follow-up is required to assess for late toxicity.
Radiation Oncology Center, Ofuna Chuo Hospital, 6-2-24 Ofuna, Kamakura, Kanagawa 247-0056, Japan takeda@1994.jukuin.keio.ac.jp.
Atsuya
A
Takeda
Radiation Oncology Center, Ofuna Chuo Hospital, 6-2-24 Ofuna, Kamakura, Kanagawa 247-0056, Japan.
Yohei
Y
Oku
Radiation Oncology Center, Ofuna Chuo Hospital, 6-2-24 Ofuna, Kamakura, Kanagawa 247-0056, Japan.
Naoko
N
Sanuki
Radiation Oncology Center, Ofuna Chuo Hospital, 6-2-24 Ofuna, Kamakura, Kanagawa 247-0056, Japan.
Takahisa
T
Eriguchi
Radiation Oncology Center, Ofuna Chuo Hospital, 6-2-24 Ofuna, Kamakura, Kanagawa 247-0056, Japan.
Yousuke
Y
Aoki
Department of Respiratory Medicine, Ofuna Chuo Hospital, 6-2-24 Ofuna, Kamakura, Kanagawa 247-0056, Japan.
Tatsuji
T
Enomoto
Department of Respiratory Medicine, Ofuna Chuo Hospital, 6-2-24 Ofuna, Kamakura, Kanagawa 247-0056, Japan Respiratory Disease Center, Yokohama City University Medical Center, Yokohama, Kanagawa, Japan.
Takeshi
T
Kaneko
Radiation Oncology Center, Ofuna Chuo Hospital, 6-2-24 Ofuna, Kamakura, Kanagawa 247-0056, Japan.
Shuichi
S
Nishimura
Department of Radiology, Tokai University School of Medicine, Sagamihara, Kanagawa, Japan.
Etsuo
E
Kunieda
D000368:Aged; D000369:Aged, 80 and over; D019583:Dose Fractionation, Radiation; D006801:Humans; D008175:Lung Neoplasms / Q000601:surgery*; D008875:Middle Aged; D011832:Radiation Injuries / Q000209:etiology* / Q000517:prevention & control; D016634:Radiosurgery / Q000009:adverse effects* / Q000379:methods*; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D016896:Treatment Outcome; D047368:Tumor Burden
Phase I study; dose-escalation study; homogeneity index; lung cancer; prescription dose; stereotactic body ridiotherapy