BMC Cancer 2009, 9:254 http://www.biomedcentral.com/1471-2407/9/254 medical oncology for consideration of postoperative adju- vant therapy, when appropriate. All attempts were made to maintain ongoing, serial patient follow-up with all patients. However, some patients have remained non- compliant and have not maintained ongoing, serial fol- low-up, even after multiple attempts to arrange such follow-up for these noncompliant patients. The volume of each BCS specimen was calculated using the formula of the volume of an ellipsoid [4/3·π·length axis radius·width axis radius·height axis radius], rather than using the formula of the volume of a cuboid [length·width·height], since the three-dimensional shape of any given BCS specimen generally better approx- imated that of an ellipsoid rather than that of a cuboid. The volume of the nine standardized re-resection margin specimens was calculated using the formula of the volume of a cuboid, rather than the formula of the volume of an ellipsoid, since each standardized re-resection margin specimen generally better approximated that of a cuboid rather than that of an ellipsoid. The three-dimensional surface area of each BCS specimen was calculated using the derived formula of the surface area of an ellipsoid [18,19]. Due to the significant complexity of the formula used to calculate the surface area of an ellipsoid, the deri- vation of that formula will not be shown within the text of the current paper. The computer program MATLAB® (The MathWorks, Inc., Natick, Massachusetts) was used to assist in the calculation the surface area of an ellipsoid from the three-dimensional measurements (length, height, and width) of each BCS specimen. The two- dimensional surface area of the face of each standardized re-resection margin specimen, based on the two largest dimensions of each standardized re-resection margin specimen (i.e., length and width), was calculated simply using the formula of the two-dimensional area of a rectan- gle [length·width]. The following percentage were then calculated: (1) the percentage of the cumulative volume of all nine standardized re-resection margins as compared to each BCS specimen volume, (2) the percentage of cumu- lative 2-dimensional surface area of all nine standardized re-resection margins as compared to the surface area of each BCS specimen, and (3) the percentage of the cumu- lative 2-dimensional surface area of all nine standardized re-resection margins as compared to the surface area of each BCS specimen minus the surface area of the overlying skin ellipse. For this study, data collection of all variables analyzed was accomplished by way of retrospective review of the elec- tronic medical records system of The Ohio State Univer- sity Medical Center. Multiple variables were assessed and evaluated, including patient demographics, tumor varia- bles, specimen variables, and patient follow-up variables. The software program SPSS® 16.0 for Windows® (SPSS, Inc., Chicago, Illinois) was used for the data analyses of all variables captured during data collection. For univariate comparisons of categorical variables, either Pearson chi- square test or Fisher exact test was utilized. For univariate comparisons of continuous variables, one-way analysis of variance (ANOVA) was utilized. All reported univariate P- values were two-sided. All univariate P-values determined to be 0.05 or less were considered to be significant. Multi- variate logistic regression analysis was performed in appropriately selected situations on all variables with a univariate P-value of 0.10 or less, in order to assess for the determination of possible independent predictors. Results From August 2003 to June 2007, 204 BCS procedures were performed for invasive breast cancer by a single sur- geon (SPP). Patient demographics and tumor characteris- tics for all 204 BCS cases are shown in Table 1 and Table 2, respectively. Of the 204 BCS procedures, 164 were per- formed as BCS procedures in patients with an intact tumor who had undergone only a minimally-invasive diagnostic breast biopsy at the time of initial diagnosis and 40 were performed as re-excision BCS procedures in patients who had previously undergone a surgical (exci- sional) biopsy as their initial diagnostic breast biopsy. Measurement variables for the BCS specimens are shown in Table 3. Measurement variables for the nine standard- ized re-resection margin specimens are shown in Table 4. The percentage of the cumulative volume of all nine standardized re-resection margins as compared to each BCS specimen volume, the percentage of cumulative 2- dimensional surface area of all nine standardized re-resec- tion margins as compared to the surface area of each BCS specimen, and the percentage of the cumulative 2-dimen- sional surface area of all nine standardized re-resection margins as compared to the surface area of each BCS spec- imen minus the surface area of the overlying skin ellipse are shown in Table 5. A description of the margin status of the BCS specimen and the re-resection margin status of the nine standard- ized re-resection margin specimens at the time of the orig- inal BCS procedure for all 204 BCS cases is shown in Table 6. Likewise, a description of the frequency of BCS cases undergoing a subsequent re-excision breast procedure and the frequency of BCS cases in which residual disease was found within those subsequent re-excision breast proce- dure specimens is shown in Table 6. Among all 204 BCS cases, 13 (6.4%) had a positive BCS specimen margin and 9 (4.4%) had a close BCS specimen margin, thus giving a total of 22 (10.8%) cases having either a positive or close BCS specimen margin (Table 6). Of those 13 cases in which there was a positive BCS spec- imen margin, eight had one positive BCS specimen mar- Page 6 of 23 (page number not for citation purposes)