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Stereotactic hypofractionated high-dose irradiation (STI) for stage I non-small cell lung cancer (NSCLC): Mature results in 300 cases of a Japanese multi-institutional study.

7045 Background: With the increasing accuracy of localization for tumor-bearing areas using various new techniques, hypofractionated or single high-dose stereotactic irradiation (STI) has been actively investigated for stage I NSCLC in Japan. The current study retrospectively evaluated Japanese multi-institutional results for high-dose STI for stage I NSCLC.


METHODS
From 1993 to 2003, stereotactic three-dimensional treatment was performed using 3-10 non-coplanar dynamic arcs or 6-20 static ports for a total of 300 stage I (median age, 75 years; T1N0M0, n = 193; T2N0M0, n = 107) patients with primary NSCLC (adenocarcinoma, n = 138; squamous cell carcinoma, n = 129; and others, n = 33) in 14 institutions. Totally 190 patients were medically inoperable, and other 110 were medically operable but selected STI. A total dose of 18-75 Gy at the isocenter was administered in 1-22 fractions. Median calculated biological effective dose (BED) was 108 Gy (range, 57-180 Gy).


RESULTS
Median follow-up period of survivors was 38 months (range; 2-128 months). Pulmonary complications of NCI-CTC criteria (version 2.0) grade ≥ 3 were noted in 9 patients (3.0%). Local progression occurred in 44 patients (14.7%), and 5-year local control rate was high (86%) for BED ≥100 Gy (n = 227) compared to 67% for <100 Gy (n = 73) (P < 0.001). Overall 5-year survival rates of operable and inoperable patients were 65% and 37%, respectively. Overall 5-year survival rates in operable cases was high (74%) for BED ≥100 Gy (n = 85) compared to 37% for <100 Gy (n = 24) (P < 0.01). In a subset of operable patients irradiated with BED ≥100, 3-year locally progression-free survival rates was high (81%) for stage IA (n = 60) compared to 67% for stage IB (n = 23) (P < 0.05) Conclusions: Local control and survival rates of STI for stage I NSCLC are better with BED ≥100 Gy compared to <100 Gy. Survival rates in selected patients (medically operable, BED ≥100 Gy) were excellent, and potentially comparable to those of surgery. Stage IB patients displayed higher rate of local progression than stage IA. We have started multi-institutional prospective study for stage IA NSCLC with a schedule of total dose of 48 Gy in 4 fractions during 4-8 days. No significant financial relationships to disclose.