RT Journal A1 Khan AJ, Vicini FA, Arthur D T1 BRachytherapy vs whole-breast irradiation for breast cancer JF JAMA JO JAMA YR 2012 FD August 8 VO 308 IS 6 SP 567 OP 568 DO 10.1001/jama.2012.8486 UL http://dx.doi.org/10.1001/jama.2012.8486 AB To the Editor: Dr Smith and colleagues1 compared outcomes of whole breast irradiation (WBI) vs brachytherapy in older women with breast cancer. We are concerned that the findings from this claims-based study may result in unnecessary anxiety for women treated with brachytherapy. Claims-based studies using large databases are subject to the limitations of retrospective analyses and can be especially problematic if data on important and validated determinants of treatment success are not available. We are unsure if subsequent mastectomy is a valid surrogate for breast conservation as indicated by the authors. Laterality of breast surgery is typically not reported in Medicare claims. Thus a patient having a contralateral mastectomy for any reason would be scored as a treatment failure in the study. Also, we believe the 5-year difference in subsequent mastectomy rates after brachytherapy of 1.77% reported in the study should not be interpreted as inferior to WBI; a difference of this magnitude is of questionable clinical relevance.2