In Regard to Koshy et al.

To the Editor: Koshy et al ( 1 ) have examined the benefits of different stereotactic ablative radiation therapy (SABR) fractionation regimens for stage I non-small cell lung cancer (NSCLC). Using the National Cancer Data Base between 2003 and 2006, the authors concluded that higher doses (>150 Gy biologically effective dose [BED]) correlated with higher overall survival (OS). This retrospective study provides meaningful information, but limitations acknowledged by the authors should have included information regarding disease-free progression or the pattern of relapse. This would have been useful for definitively ensuring that this OS benefit is really attributable to higher BED. Several studies suggest a dose–response relationship for local tumor control up to 100 Gy ( 2 ), but we believe that a benefit in OS could be attributed to confounding factors that are discussed below.