BACKGROUND:The most common regimen of stereotactic body radiotherapy (SBRT) for stage I nonsmall cell lung cancer in Japan is 48 grays (Gy) in 4 fractions over 4 days. Radiobiologically, however, higher doses are necessary to control larger tumors, and interfraction intervals should be >24 hours to take advantage of reoxygenation. In this study, the authors tested the following regimen: For tumors that measured <1.5 cm, 1.5 to 3.0 cm, and >3.0 cm in greatest dimension, radiation doses of 44 Gy, 48 Gy, and 52 Gy, respectively, were given in 4 fractions with interfraction intervals of !3 days. METHODS: Among 180 patients with histologically proven disease who entered the study, 120 were medically inoperable, and 60 were operable. The median patient age was 77 years (range, 29-92 years). SBRT was performed with 6-megavolt photons using 4 noncoplanar beams and 3 coplanar beams. Isocenter doses of 44 Gy, 48 Gy, and 52 Gy were received by 4 patients, 124 patients, and 52 patients, respectively. RESULTS: The overall survival rate for all 180 patients was 69% at 3 years and 52% at 5 years. The 3-year survival rate was 74% for operable patients and 59% for medically inoperable patients (P ¼ .080). The 3-year local control rate was 86% for tumors 3 cm (44/48 Gy) and 73% for tumors >3 cm (52 Gy; P ¼ .050). Grade !2 radiation pneumonitis developed in 13% of patients (10% of the 44-Gy/48-Gy group and 21% of the 52-Gy group; P ¼ .056). All other grade 2 toxicities developed in <4% of patients. CONCLUSIONS: The SBRT protocol used in this study yielded reasonable local control and overall survival rates and acceptable toxicity. Dose escalation is being investigated.

Our first prospective SBRT study yielded reasonable local control and overall survival rates and acceptable toxicity. Refinement of the protocol including dose escalation may lead to better outcome.

BackgroundThe treatment schedules for stereotactic body radiotherapy (SBRT) for lung cancer vary from institution to institution. Several reports have indicated that stage IB patients had worse outcomes than stage IA patients when the same dose was used. We evaluated the clinical outcomes of SBRT for stage I non-small cell lung cancer (NSCLC) treated with different doses depending on tumor diameter.MethodsBetween February 2004 and November 2008, 124 patients with stage I NSCLC underwent SBRT. Total doses of 44, 48, and 52 Gy were administered for tumors with a longest diameter of less than 1.5 cm, 1.5-3 cm, and larger than 3 cm, respectively. All doses were given in 4 fractions.ResultsFor all 124 patients, overall survival was 71%, cause-specific survival was 87%, progression-free survival was 60%, and local control was 80%, at 3 years. The 3-year overall survival was 79% for 85 stage IA patients treated with 48 Gy and 56% for 37 stage IB patients treated with 52 Gy (p = 0.05). At 3 years, cause-specific survival was 91% for the former group and 79% for the latter (p = 0.18), and progression-free survival was 62% versus 54% (p = 0.30). The 3-year local control rate was 81% versus 74% (p = 0.35). The cumulative incidence of grade 2 or 3 radiation pneumonitis was 11% in stage IA patients and 30% in stage IB patients (p = 0.02).ConclusionsThere was no difference in local control between stage IA and IB tumors despite the difference in tumor size. The benefit of increasing the SBRT dose for larger tumors should be investigated further.

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