Stereotactic body radiotherapy using a radiobiology-based regimen for stage I non-small-cell XXXX : five-year mature results.

@entity1 @entity137 @entity55 @entity5 @entity2
INTRODUCTION: Although the protocol of 48 Gy in four fractions over 4 days has been most often employed in stereotactic body radiotherapy (SBRT) for stage I non-small-cell @entity2 in Japan, higher doses are necessary to control larger @entity5 , and interfraction intervals should be longer than 24 hours to take advantage of reoxygenation. We report the final results of our study testing the following regimen: for @entity5 less than 1.5, 1.5-3, and greater than 3   cm in diameter, 44, 48, and 52 Gy, respectively, were given in four fractions with interfraction intervals of greater than or equal to 3 days. METHODS: Among 180 histologically proven @entity1 entered, 120 were medically inoperable and 60 were operable. The median @entity1 age was 77 years (range, 29-89). SBRT was performed with 6-MV photons using four noncoplanar and three coplanar beams. Isocenter doses of 44, 48, and 52 Gy were given to four, 124, and 52 @entity1 , respectively. RESULTS: The 5-year overall survival rate was 52.2% for all 180 @entity1 and 66% for 60 operable @entity1 . The 5-year local control rate was 86% for @entity5 less than or equal to 3   cm (44/48 Gy) and 73% for @entity5 greater than 3   cm (52 Gy; p = 0.076). Grade greater than or equal to 2 radiation @entity55 developed in 13% (10% for the 44/48-Gy group and 21% for the 52-Gy group; p = 0.056). Other grade 2 @entity137 were all less than 4%. CONCLUSIONS: Our first prospective SBRT study yielded reasonable local control and overall survival rates and acceptable @entity137 . Refinement of the protocol including dose escalation may lead to better outcome.
