Is the difference in reexcision rate of various margin assessment methods due solely to difference in volume excised

593 Background: The inability to achieve clear margins in a single operation continues to plague breast surgeons, resulting in reexcision rates of up to 70%. We explored 3 different methods of margin assessment (METHODs) and found that the cavity shave technique (C) resulted in significantly lower reexcision rates, but larger volumes of excision. Here, we assessed whether the lower reexcision rate was due solely to the larger volume excised. Methods: Our study population consisted of consecutive patients undergoing breast conservation with sentinel node biopsy after a needle biopsy diagnosis of invasive carcinoma or DCIS from July-December of 2003, 2004, and 2008. These 3 time periods corresponded to 3 METHODs: perpendicular (P) (pathologist evaluated perpendicular margins in serial sections of the specimen, 2003), tangential shaved (T) (pathologist shaved margins from the specimen, 2004), and cavity shaved (C) (surgeon shaved margins from the cavity, 2008). Volume of tissue excised at initial excision wa...